diff --git a/meson.build b/meson.build
index b89b713e79..a90855f59a 100644
--- a/meson.build
+++ b/meson.build
@@ -3425,6 +3425,7 @@ if have_system
     'hw/pci-host',
     'hw/ppc',
     'hw/rtc',
+    'hw/riscv',
     'hw/s390x',
     'hw/scsi',
     'hw/sd',
diff --git a/hw/riscv/riscv-iommu-bits.h b/hw/riscv/riscv-iommu-bits.h
index c46d7d18ab..b1c477f5c3 100644
--- a/hw/riscv/riscv-iommu-bits.h
+++ b/hw/riscv/riscv-iommu-bits.h
@@ -69,6 +69,14 @@ struct riscv_iommu_pq_record {
 /* 5.3 IOMMU Capabilities (64bits) */
 #define RISCV_IOMMU_REG_CAP             0x0000
 #define RISCV_IOMMU_CAP_VERSION         GENMASK_ULL(7, 0)
+#define RISCV_IOMMU_CAP_SV32            BIT_ULL(8)
+#define RISCV_IOMMU_CAP_SV39            BIT_ULL(9)
+#define RISCV_IOMMU_CAP_SV48            BIT_ULL(10)
+#define RISCV_IOMMU_CAP_SV57            BIT_ULL(11)
+#define RISCV_IOMMU_CAP_SV32X4          BIT_ULL(16)
+#define RISCV_IOMMU_CAP_SV39X4          BIT_ULL(17)
+#define RISCV_IOMMU_CAP_SV48X4          BIT_ULL(18)
+#define RISCV_IOMMU_CAP_SV57X4          BIT_ULL(19)
 #define RISCV_IOMMU_CAP_MSI_FLAT        BIT_ULL(22)
 #define RISCV_IOMMU_CAP_MSI_MRIF        BIT_ULL(23)
 #define RISCV_IOMMU_CAP_T2GPA           BIT_ULL(26)
@@ -80,7 +88,9 @@ struct riscv_iommu_pq_record {
 
 /* 5.4 Features control register (32bits) */
 #define RISCV_IOMMU_REG_FCTL            0x0008
+#define RISCV_IOMMU_FCTL_BE             BIT(0)
 #define RISCV_IOMMU_FCTL_WSI            BIT(1)
+#define RISCV_IOMMU_FCTL_GXL            BIT(2)
 
 /* 5.5 Device-directory-table pointer (64bits) */
 #define RISCV_IOMMU_REG_DDTP            0x0010
@@ -175,6 +185,10 @@ enum {
 
 /* 5.27 Interrupt cause to vector (64bits) */
 #define RISCV_IOMMU_REG_ICVEC           0x02F8
+#define RISCV_IOMMU_ICVEC_CIV           GENMASK_ULL(3, 0)
+#define RISCV_IOMMU_ICVEC_FIV           GENMASK_ULL(7, 4)
+#define RISCV_IOMMU_ICVEC_PMIV          GENMASK_ULL(11, 8)
+#define RISCV_IOMMU_ICVEC_PIV           GENMASK_ULL(15, 12)
 
 /* 5.28 MSI Configuration table (32 * 64bits) */
 #define RISCV_IOMMU_REG_MSI_CONFIG      0x0300
@@ -203,6 +217,8 @@ struct riscv_iommu_dc {
 #define RISCV_IOMMU_DC_TC_DTF           BIT_ULL(4)
 #define RISCV_IOMMU_DC_TC_PDTV          BIT_ULL(5)
 #define RISCV_IOMMU_DC_TC_PRPR          BIT_ULL(6)
+#define RISCV_IOMMU_DC_TC_GADE          BIT_ULL(7)
+#define RISCV_IOMMU_DC_TC_SADE          BIT_ULL(8)
 #define RISCV_IOMMU_DC_TC_DPE           BIT_ULL(9)
 #define RISCV_IOMMU_DC_TC_SBE           BIT_ULL(10)
 #define RISCV_IOMMU_DC_TC_SXL           BIT_ULL(11)
@@ -309,9 +325,11 @@ enum riscv_iommu_fq_causes {
 
 /* Translation attributes fields */
 #define RISCV_IOMMU_PC_TA_V             BIT_ULL(0)
+#define RISCV_IOMMU_PC_TA_RESERVED      GENMASK_ULL(63, 32)
 
 /* First stage context fields */
 #define RISCV_IOMMU_PC_FSC_PPN          GENMASK_ULL(43, 0)
+#define RISCV_IOMMU_PC_FSC_RESERVED     GENMASK_ULL(59, 44)
 
 enum riscv_iommu_fq_ttypes {
     RISCV_IOMMU_FQ_TTYPE_NONE = 0,
diff --git a/hw/riscv/riscv-iommu.h b/hw/riscv/riscv-iommu.h
new file mode 100644
index 0000000000..95b4ce8d50
--- /dev/null
+++ b/hw/riscv/riscv-iommu.h
@@ -0,0 +1,145 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_STATE_H
+#define HW_RISCV_IOMMU_STATE_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+
+#include "hw/riscv/iommu.h"
+
+struct RISCVIOMMUState {
+    /*< private >*/
+    DeviceState parent_obj;
+
+    /*< public >*/
+    uint32_t version;     /* Reported interface version number */
+    uint32_t pid_bits;    /* process identifier width */
+    uint32_t bus;         /* PCI bus mapping for non-root endpoints */
+
+    uint64_t cap;         /* IOMMU supported capabilities */
+    uint64_t fctl;        /* IOMMU enabled features */
+    uint64_t icvec_avail_vectors;  /* Available interrupt vectors in ICVEC */
+
+    bool enable_off;      /* Enable out-of-reset OFF mode (DMA disabled) */
+    bool enable_msi;      /* Enable MSI remapping */
+    bool enable_s_stage;  /* Enable S/VS-Stage translation */
+    bool enable_g_stage;  /* Enable G-Stage translation */
+
+    /* IOMMU Internal State */
+    uint64_t ddtp;        /* Validated Device Directory Tree Root Pointer */
+
+    dma_addr_t cq_addr;   /* Command queue base physical address */
+    dma_addr_t fq_addr;   /* Fault/event queue base physical address */
+    dma_addr_t pq_addr;   /* Page request queue base physical address */
+
+    uint32_t cq_mask;     /* Command queue index bit mask */
+    uint32_t fq_mask;     /* Fault/event queue index bit mask */
+    uint32_t pq_mask;     /* Page request queue index bit mask */
+
+    /* interrupt notifier */
+    void (*notify)(RISCVIOMMUState *iommu, unsigned vector);
+
+    /* IOMMU State Machine */
+    QemuThread core_proc; /* Background processing thread */
+    QemuMutex core_lock;  /* Global IOMMU lock, used for cache/regs updates */
+    QemuCond core_cond;   /* Background processing wake up signal */
+    unsigned core_exec;   /* Processing thread execution actions */
+
+    /* IOMMU target address space */
+    AddressSpace *target_as;
+    MemoryRegion *target_mr;
+
+    /* MSI / MRIF access trap */
+    AddressSpace trap_as;
+    MemoryRegion trap_mr;
+
+    GHashTable *ctx_cache;          /* Device translation Context Cache */
+    QemuMutex ctx_lock;      /* Device translation Cache update lock */
+
+    /* MMIO Hardware Interface */
+    MemoryRegion regs_mr;
+    QemuSpin regs_lock;
+    uint8_t *regs_rw;  /* register state (user write) */
+    uint8_t *regs_wc;  /* write-1-to-clear mask */
+    uint8_t *regs_ro;  /* read-only mask */
+
+    QLIST_ENTRY(RISCVIOMMUState) iommus;
+    QLIST_HEAD(, RISCVIOMMUSpace) spaces;
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+         Error **errp);
+
+/* private helpers */
+
+/* Register helper functions */
+static inline uint32_t riscv_iommu_reg_mod32(RISCVIOMMUState *s,
+    unsigned idx, uint32_t set, uint32_t clr)
+{
+    uint32_t val;
+    qemu_spin_lock(&s->regs_lock);
+    val = ldl_le_p(s->regs_rw + idx);
+    stl_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    qemu_spin_unlock(&s->regs_lock);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set32(RISCVIOMMUState *s,
+    unsigned idx, uint32_t set)
+{
+    qemu_spin_lock(&s->regs_lock);
+    stl_le_p(s->regs_rw + idx, set);
+    qemu_spin_unlock(&s->regs_lock);
+}
+
+static inline uint32_t riscv_iommu_reg_get32(RISCVIOMMUState *s,
+    unsigned idx)
+{
+    return ldl_le_p(s->regs_rw + idx);
+}
+
+static inline uint64_t riscv_iommu_reg_mod64(RISCVIOMMUState *s,
+    unsigned idx, uint64_t set, uint64_t clr)
+{
+    uint64_t val;
+    qemu_spin_lock(&s->regs_lock);
+    val = ldq_le_p(s->regs_rw + idx);
+    stq_le_p(s->regs_rw + idx, (val & ~clr) | set);
+    qemu_spin_unlock(&s->regs_lock);
+    return val;
+}
+
+static inline void riscv_iommu_reg_set64(RISCVIOMMUState *s,
+    unsigned idx, uint64_t set)
+{
+    qemu_spin_lock(&s->regs_lock);
+    stq_le_p(s->regs_rw + idx, set);
+    qemu_spin_unlock(&s->regs_lock);
+}
+
+static inline uint64_t riscv_iommu_reg_get64(RISCVIOMMUState *s,
+    unsigned idx)
+{
+    return ldq_le_p(s->regs_rw + idx);
+}
+
+
+
+#endif
diff --git a/hw/riscv/trace.h b/hw/riscv/trace.h
new file mode 100644
index 0000000000..8c0e3ca1f3
--- /dev/null
+++ b/hw/riscv/trace.h
@@ -0,0 +1 @@
+#include "trace/trace-hw_riscv.h"
diff --git a/include/hw/riscv/iommu.h b/include/hw/riscv/iommu.h
new file mode 100644
index 0000000000..070ee69973
--- /dev/null
+++ b/include/hw/riscv/iommu.h
@@ -0,0 +1,36 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU
+ *
+ * Copyright (C) 2022-2023 Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef HW_RISCV_IOMMU_H
+#define HW_RISCV_IOMMU_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+
+#define TYPE_RISCV_IOMMU "riscv-iommu"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUState, RISCV_IOMMU)
+typedef struct RISCVIOMMUState RISCVIOMMUState;
+
+#define TYPE_RISCV_IOMMU_MEMORY_REGION "riscv-iommu-mr"
+typedef struct RISCVIOMMUSpace RISCVIOMMUSpace;
+
+#define TYPE_RISCV_IOMMU_PCI "riscv-iommu-pci"
+OBJECT_DECLARE_SIMPLE_TYPE(RISCVIOMMUStatePci, RISCV_IOMMU_PCI)
+typedef struct RISCVIOMMUStatePci RISCVIOMMUStatePci;
+
+#endif
diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
new file mode 100644
index 0000000000..061a5efe19
--- /dev/null
+++ b/hw/riscv/riscv-iommu.c
@@ -0,0 +1,2050 @@
+/*
+ * QEMU emulation of an RISC-V IOMMU
+ *
+ * Copyright (C) 2021-2023, Rivos Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/pci/pci_device.h"
+#include "hw/qdev-properties.h"
+#include "hw/riscv/riscv_hart.h"
+#include "migration/vmstate.h"
+#include "qapi/error.h"
+#include "qemu/timer.h"
+
+#include "cpu_bits.h"
+#include "riscv-iommu.h"
+#include "riscv-iommu-bits.h"
+#include "trace.h"
+
+#define LIMIT_CACHE_CTX               (1U << 7)
+#define LIMIT_CACHE_IOT               (1U << 20)
+
+/* Physical page number coversions */
+#define PPN_PHYS(ppn)                 ((ppn) << TARGET_PAGE_BITS)
+#define PPN_DOWN(phy)                 ((phy) >> TARGET_PAGE_BITS)
+
+typedef struct RISCVIOMMUContext RISCVIOMMUContext;
+typedef struct RISCVIOMMUEntry RISCVIOMMUEntry;
+
+/* Device assigned I/O address space */
+struct RISCVIOMMUSpace {
+    IOMMUMemoryRegion iova_mr;  /* IOVA memory region for attached device */
+    AddressSpace iova_as;       /* IOVA address space for attached device */
+    RISCVIOMMUState *iommu;     /* Managing IOMMU device state */
+    uint32_t devid;             /* Requester identifier, AKA device_id */
+    bool notifier;              /* IOMMU unmap notifier enabled */
+    QLIST_ENTRY(RISCVIOMMUSpace) list;
+};
+
+/* Device translation context state. */
+struct RISCVIOMMUContext {
+    uint64_t devid:24;          /* Requester Id, AKA device_id */
+    uint64_t process_id:20;     /* Process ID. PASID for PCIe */
+    uint64_t __rfu:20;          /* reserved */
+    uint64_t tc;                /* Translation Control */
+    uint64_t ta;                /* Translation Attributes */
+    uint64_t satp;              /* S-Stage address translation and protection */
+    uint64_t gatp;              /* G-Stage address translation and protection */
+    uint64_t msi_addr_mask;     /* MSI filtering - address mask */
+    uint64_t msi_addr_pattern;  /* MSI filtering - address pattern */
+    uint64_t msiptp;            /* MSI redirection page table pointer */
+};
+
+/* IOMMU index for transactions without process_id specified. */
+#define RISCV_IOMMU_NOPROCID 0
+
+static uint8_t riscv_iommu_get_icvec_vector(uint32_t icvec, uint32_t vec_type)
+{
+    switch (vec_type) {
+    case RISCV_IOMMU_INTR_CQ:
+        return icvec & RISCV_IOMMU_ICVEC_CIV;
+    case RISCV_IOMMU_INTR_FQ:
+        return icvec & RISCV_IOMMU_ICVEC_FIV >> 4;
+    case RISCV_IOMMU_INTR_PM:
+        return icvec & RISCV_IOMMU_ICVEC_PMIV >> 8;
+    case RISCV_IOMMU_INTR_PQ:
+        return icvec & RISCV_IOMMU_ICVEC_PIV >> 12;
+    default:
+        g_assert_not_reached();
+    }
+}
+
+static void riscv_iommu_notify(RISCVIOMMUState *s, int vec_type)
+{
+    const uint32_t fctl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FCTL);
+    uint32_t ipsr, icvec, vector;
+
+    if (fctl & RISCV_IOMMU_FCTL_WSI || !s->notify) {
+        return;
+    }
+
+    icvec = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_ICVEC);
+    ipsr = riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_IPSR, (1 << vec_type), 0);
+
+    if (!(ipsr & (1 << vec_type))) {
+        vector = riscv_iommu_get_icvec_vector(icvec, vec_type);
+        s->notify(s, vector);
+        trace_riscv_iommu_notify_int_vector(vec_type, vector);
+    }
+}
+
+static void riscv_iommu_fault(RISCVIOMMUState *s,
+                              struct riscv_iommu_fq_record *ev)
+{
+    uint32_t ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+    uint32_t head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQH) & s->fq_mask;
+    uint32_t tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQT) & s->fq_mask;
+    uint32_t next = (tail + 1) & s->fq_mask;
+    uint32_t devid = get_field(ev->hdr, RISCV_IOMMU_FQ_HDR_DID);
+
+    trace_riscv_iommu_flt(s->parent_obj.id, PCI_BUS_NUM(devid), PCI_SLOT(devid),
+                          PCI_FUNC(devid), ev->hdr, ev->iotval);
+
+    if (!(ctrl & RISCV_IOMMU_FQCSR_FQON) ||
+        !!(ctrl & (RISCV_IOMMU_FQCSR_FQOF | RISCV_IOMMU_FQCSR_FQMF))) {
+        return;
+    }
+
+    if (head == next) {
+        riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR,
+                              RISCV_IOMMU_FQCSR_FQOF, 0);
+    } else {
+        dma_addr_t addr = s->fq_addr + tail * sizeof(*ev);
+        if (dma_memory_write(s->target_as, addr, ev, sizeof(*ev),
+                             MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR,
+                                  RISCV_IOMMU_FQCSR_FQMF, 0);
+        } else {
+            riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_FQT, next);
+        }
+    }
+
+    if (ctrl & RISCV_IOMMU_FQCSR_FIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_FQ);
+    }
+}
+
+static void riscv_iommu_pri(RISCVIOMMUState *s,
+    struct riscv_iommu_pq_record *pr)
+{
+    uint32_t ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+    uint32_t head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQH) & s->pq_mask;
+    uint32_t tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQT) & s->pq_mask;
+    uint32_t next = (tail + 1) & s->pq_mask;
+    uint32_t devid = get_field(pr->hdr, RISCV_IOMMU_PREQ_HDR_DID);
+
+    trace_riscv_iommu_pri(s->parent_obj.id, PCI_BUS_NUM(devid), PCI_SLOT(devid),
+                          PCI_FUNC(devid), pr->payload);
+
+    if (!(ctrl & RISCV_IOMMU_PQCSR_PQON) ||
+        !!(ctrl & (RISCV_IOMMU_PQCSR_PQOF | RISCV_IOMMU_PQCSR_PQMF))) {
+        return;
+    }
+
+    if (head == next) {
+        riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR,
+                              RISCV_IOMMU_PQCSR_PQOF, 0);
+    } else {
+        dma_addr_t addr = s->pq_addr + tail * sizeof(*pr);
+        if (dma_memory_write(s->target_as, addr, pr, sizeof(*pr),
+                             MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR,
+                                  RISCV_IOMMU_PQCSR_PQMF, 0);
+        } else {
+            riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_PQT, next);
+        }
+    }
+
+    if (ctrl & RISCV_IOMMU_PQCSR_PIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_PQ);
+    }
+}
+
+/* Portable implementation of pext_u64, bit-mask extraction. */
+static uint64_t _pext_u64(uint64_t val, uint64_t ext)
+{
+    uint64_t ret = 0;
+    uint64_t rot = 1;
+
+    while (ext) {
+        if (ext & 1) {
+            if (val & 1) {
+                ret |= rot;
+            }
+            rot <<= 1;
+        }
+        val >>= 1;
+        ext >>= 1;
+    }
+
+    return ret;
+}
+
+/* Check if GPA matches MSI/MRIF pattern. */
+static bool riscv_iommu_msi_check(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    dma_addr_t gpa)
+{
+    if (!s->enable_msi) {
+        return false;
+    }
+
+    if (get_field(ctx->msiptp, RISCV_IOMMU_DC_MSIPTP_MODE) !=
+        RISCV_IOMMU_DC_MSIPTP_MODE_FLAT) {
+        return false; /* Invalid MSI/MRIF mode */
+    }
+
+    if ((PPN_DOWN(gpa) ^ ctx->msi_addr_pattern) & ~ctx->msi_addr_mask) {
+        return false; /* GPA not in MSI range defined by AIA IMSIC rules. */
+    }
+
+    return true;
+}
+
+/*
+ * RISCV IOMMU Address Translation Lookup - Page Table Walk
+ *
+ * Note: Code is based on get_physical_address() from target/riscv/cpu_helper.c
+ * Both implementation can be merged into single helper function in future.
+ * Keeping them separate for now, as error reporting and flow specifics are
+ * sufficiently different for separate implementation.
+ *
+ * @s        : IOMMU Device State
+ * @ctx      : Translation context for device id and process address space id.
+ * @iotlb    : translation data: physical address and access mode.
+ * @return   : success or fault cause code.
+ */
+static int riscv_iommu_spa_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    IOMMUTLBEntry *iotlb)
+{
+    dma_addr_t addr, base;
+    uint64_t satp, gatp, pte;
+    bool en_s, en_g;
+    struct {
+        unsigned char step;
+        unsigned char levels;
+        unsigned char ptidxbits;
+        unsigned char ptesize;
+    } sc[2];
+    /* Translation stage phase */
+    enum {
+        S_STAGE = 0,
+        G_STAGE = 1,
+    } pass;
+
+    satp = get_field(ctx->satp, RISCV_IOMMU_ATP_MODE_FIELD);
+    gatp = get_field(ctx->gatp, RISCV_IOMMU_ATP_MODE_FIELD);
+
+    en_s = satp != RISCV_IOMMU_DC_FSC_MODE_BARE;
+    en_g = gatp != RISCV_IOMMU_DC_IOHGATP_MODE_BARE;
+
+    /*
+     * Early check for MSI address match when IOVA == GPA. This check
+     * is required to ensure MSI translation is applied in case
+     * first-stage translation is set to BARE mode. In this case IOVA
+     * provided is a valid GPA. Running translation through page walk
+     * second stage translation will incorrectly try to translate GPA
+     * to host physical page, likely hitting IOPF.
+     */
+    if ((iotlb->perm & IOMMU_WO) &&
+        riscv_iommu_msi_check(s, ctx, iotlb->iova)) {
+        iotlb->target_as = &s->trap_as;
+        iotlb->translated_addr = iotlb->iova;
+        iotlb->addr_mask = ~TARGET_PAGE_MASK;
+        return 0;
+    }
+
+    /* Exit early for pass-through mode. */
+    if (!(en_s || en_g)) {
+        iotlb->translated_addr = iotlb->iova;
+        iotlb->addr_mask = ~TARGET_PAGE_MASK;
+        /* Allow R/W in pass-through mode */
+        iotlb->perm = IOMMU_RW;
+        return 0;
+    }
+
+    /* S/G translation parameters. */
+    for (pass = 0; pass < 2; pass++) {
+        uint32_t sv_mode;
+
+        sc[pass].step = 0;
+        if (pass ? (s->fctl & RISCV_IOMMU_FCTL_GXL) :
+            (ctx->tc & RISCV_IOMMU_DC_TC_SXL)) {
+            /* 32bit mode for GXL/SXL == 1 */
+            switch (pass ? gatp : satp) {
+            case RISCV_IOMMU_DC_IOHGATP_MODE_BARE:
+                sc[pass].levels    = 0;
+                sc[pass].ptidxbits = 0;
+                sc[pass].ptesize   = 0;
+                break;
+            case RISCV_IOMMU_DC_IOHGATP_MODE_SV32X4:
+                sv_mode = pass ? RISCV_IOMMU_CAP_SV32X4 : RISCV_IOMMU_CAP_SV32;
+                if (!(s->cap & sv_mode)) {
+                    return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+                }
+                sc[pass].levels    = 2;
+                sc[pass].ptidxbits = 10;
+                sc[pass].ptesize   = 4;
+                break;
+            default:
+                return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+            }
+        } else {
+            /* 64bit mode for GXL/SXL == 0 */
+            switch (pass ? gatp : satp) {
+            case RISCV_IOMMU_DC_IOHGATP_MODE_BARE:
+                sc[pass].levels    = 0;
+                sc[pass].ptidxbits = 0;
+                sc[pass].ptesize   = 0;
+                break;
+            case RISCV_IOMMU_DC_IOHGATP_MODE_SV39X4:
+                sv_mode = pass ? RISCV_IOMMU_CAP_SV39X4 : RISCV_IOMMU_CAP_SV39;
+                if (!(s->cap & sv_mode)) {
+                    return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+                }
+                sc[pass].levels    = 3;
+                sc[pass].ptidxbits = 9;
+                sc[pass].ptesize   = 8;
+                break;
+            case RISCV_IOMMU_DC_IOHGATP_MODE_SV48X4:
+                sv_mode = pass ? RISCV_IOMMU_CAP_SV48X4 : RISCV_IOMMU_CAP_SV48;
+                if (!(s->cap & sv_mode)) {
+                    return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+                }
+                sc[pass].levels    = 4;
+                sc[pass].ptidxbits = 9;
+                sc[pass].ptesize   = 8;
+                break;
+            case RISCV_IOMMU_DC_IOHGATP_MODE_SV57X4:
+                sv_mode = pass ? RISCV_IOMMU_CAP_SV57X4 : RISCV_IOMMU_CAP_SV57;
+                if (!(s->cap & sv_mode)) {
+                    return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+                }
+                sc[pass].levels    = 5;
+                sc[pass].ptidxbits = 9;
+                sc[pass].ptesize   = 8;
+                break;
+            default:
+                return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+            }
+        }
+    };
+
+    /* S/G stages translation tables root pointers */
+    gatp = PPN_PHYS(get_field(ctx->gatp, RISCV_IOMMU_ATP_PPN_FIELD));
+    satp = PPN_PHYS(get_field(ctx->satp, RISCV_IOMMU_ATP_PPN_FIELD));
+    addr = (en_s && en_g) ? satp : iotlb->iova;
+    base = en_g ? gatp : satp;
+    pass = en_g ? G_STAGE : S_STAGE;
+
+    do {
+        const unsigned widened = (pass && !sc[pass].step) ? 2 : 0;
+        const unsigned va_bits = widened + sc[pass].ptidxbits;
+        const unsigned va_skip = TARGET_PAGE_BITS + sc[pass].ptidxbits *
+                                 (sc[pass].levels - 1 - sc[pass].step);
+        const unsigned idx = (addr >> va_skip) & ((1 << va_bits) - 1);
+        const dma_addr_t pte_addr = base + idx * sc[pass].ptesize;
+        const bool ade =
+            ctx->tc & (pass ? RISCV_IOMMU_DC_TC_GADE : RISCV_IOMMU_DC_TC_SADE);
+
+        /* Address range check before first level lookup */
+        if (!sc[pass].step) {
+            const uint64_t va_mask = (1ULL << (va_skip + va_bits)) - 1;
+            if ((addr & va_mask) != addr) {
+                return RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED;
+            }
+        }
+
+        /* Read page table entry */
+        if (dma_memory_read(s->target_as, pte_addr, &pte,
+                sc[pass].ptesize, MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            return (iotlb->perm & IOMMU_WO) ? RISCV_IOMMU_FQ_CAUSE_WR_FAULT
+                                            : RISCV_IOMMU_FQ_CAUSE_RD_FAULT;
+        }
+
+        if (sc[pass].ptesize == 4) {
+            pte = (uint64_t) le32_to_cpu(*((uint32_t *)&pte));
+        } else {
+            pte = le64_to_cpu(pte);
+        }
+
+        sc[pass].step++;
+        hwaddr ppn = pte >> PTE_PPN_SHIFT;
+
+        if (!(pte & PTE_V)) {
+            break;                /* Invalid PTE */
+        } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
+            base = PPN_PHYS(ppn); /* Inner PTE, continue walking */
+        } else if ((pte & (PTE_R | PTE_W | PTE_X)) == PTE_W) {
+            break;                /* Reserved leaf PTE flags: PTE_W */
+        } else if ((pte & (PTE_R | PTE_W | PTE_X)) == (PTE_W | PTE_X)) {
+            break;                /* Reserved leaf PTE flags: PTE_W + PTE_X */
+        } else if (ppn & ((1ULL << (va_skip - TARGET_PAGE_BITS)) - 1)) {
+            break;                /* Misaligned PPN */
+        } else if ((iotlb->perm & IOMMU_RO) && !(pte & PTE_R)) {
+            break;                /* Read access check failed */
+        } else if ((iotlb->perm & IOMMU_WO) && !(pte & PTE_W)) {
+            break;                /* Write access check failed */
+        } else if ((iotlb->perm & IOMMU_RO) && !ade && !(pte & PTE_A)) {
+            break;                /* Access bit not set */
+        } else if ((iotlb->perm & IOMMU_WO) && !ade && !(pte & PTE_D)) {
+            break;                /* Dirty bit not set */
+        } else {
+            /* Leaf PTE, translation completed. */
+            sc[pass].step = sc[pass].levels;
+            base = PPN_PHYS(ppn) | (addr & ((1ULL << va_skip) - 1));
+            /* Update address mask based on smallest translation granularity */
+            iotlb->addr_mask &= (1ULL << va_skip) - 1;
+            /* Continue with S-Stage translation? */
+            if (pass && sc[0].step != sc[0].levels) {
+                pass = S_STAGE;
+                addr = iotlb->iova;
+                continue;
+            }
+            /* Translation phase completed (GPA or SPA) */
+            iotlb->translated_addr = base;
+            iotlb->perm = (pte & PTE_W) ? ((pte & PTE_R) ? IOMMU_RW : IOMMU_WO)
+                                                         : IOMMU_RO;
+
+            /* Check MSI GPA address match */
+            if (pass == S_STAGE && (iotlb->perm & IOMMU_WO) &&
+                riscv_iommu_msi_check(s, ctx, base)) {
+                /* Trap MSI writes and return GPA address. */
+                iotlb->target_as = &s->trap_as;
+                iotlb->addr_mask = ~TARGET_PAGE_MASK;
+                return 0;
+            }
+
+            /* Continue with G-Stage translation? */
+            if (!pass && en_g) {
+                pass = G_STAGE;
+                addr = base;
+                base = gatp;
+                sc[pass].step = 0;
+                continue;
+            }
+
+            return 0;
+        }
+
+        if (sc[pass].step == sc[pass].levels) {
+            break; /* Can't find leaf PTE */
+        }
+
+        /* Continue with G-Stage translation? */
+        if (!pass && en_g) {
+            pass = G_STAGE;
+            addr = base;
+            base = gatp;
+            sc[pass].step = 0;
+        }
+    } while (1);
+
+    return (iotlb->perm & IOMMU_WO) ?
+                (pass ? RISCV_IOMMU_FQ_CAUSE_WR_FAULT_VS :
+                        RISCV_IOMMU_FQ_CAUSE_WR_FAULT_S) :
+                (pass ? RISCV_IOMMU_FQ_CAUSE_RD_FAULT_VS :
+                        RISCV_IOMMU_FQ_CAUSE_RD_FAULT_S);
+}
+
+static void riscv_iommu_report_fault(RISCVIOMMUState *s,
+                                     RISCVIOMMUContext *ctx,
+                                     uint32_t fault_type, uint32_t cause,
+                                     bool pv,
+                                     uint64_t iotval, uint64_t iotval2)
+{
+    struct riscv_iommu_fq_record ev = { 0 };
+
+    if (ctx->tc & RISCV_IOMMU_DC_TC_DTF) {
+        switch (cause) {
+        case RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED:
+        case RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT:
+        case RISCV_IOMMU_FQ_CAUSE_DDT_INVALID:
+        case RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED:
+        case RISCV_IOMMU_FQ_CAUSE_DDT_CORRUPTED:
+        case RISCV_IOMMU_FQ_CAUSE_INTERNAL_DP_ERROR:
+        case RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT:
+            break;
+        default:
+            /* DTF prevents reporting a fault for this given cause */
+            return;
+        }
+    }
+
+    ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_CAUSE, cause);
+    ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_TTYPE, fault_type);
+    ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_DID, ctx->devid);
+    ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PV, true);
+
+    if (pv) {
+        ev.hdr = set_field(ev.hdr, RISCV_IOMMU_FQ_HDR_PID, ctx->process_id);
+    }
+
+    ev.iotval = iotval;
+    ev.iotval2 = iotval2;
+
+    riscv_iommu_fault(s, &ev);
+}
+
+/* Redirect MSI write for given GPA. */
+static MemTxResult riscv_iommu_msi_write(RISCVIOMMUState *s,
+    RISCVIOMMUContext *ctx, uint64_t gpa, uint64_t data,
+    unsigned size, MemTxAttrs attrs)
+{
+    MemTxResult res;
+    dma_addr_t addr;
+    uint64_t intn;
+    uint32_t n190;
+    uint64_t pte[2];
+    int fault_type = RISCV_IOMMU_FQ_TTYPE_UADDR_WR;
+    int cause;
+
+    /* Interrupt File Number */
+    intn = _pext_u64(PPN_DOWN(gpa), ctx->msi_addr_mask);
+    if (intn >= 256) {
+        /* Interrupt file number out of range */
+        res = MEMTX_ACCESS_ERROR;
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT;
+        goto err;
+    }
+
+    /* fetch MSI PTE */
+    addr = PPN_PHYS(get_field(ctx->msiptp, RISCV_IOMMU_DC_MSIPTP_PPN));
+    addr = addr | (intn * sizeof(pte));
+    res = dma_memory_read(s->target_as, addr, &pte, sizeof(pte),
+            MEMTXATTRS_UNSPECIFIED);
+    if (res != MEMTX_OK) {
+        if (res == MEMTX_DECODE_ERROR) {
+            cause = RISCV_IOMMU_FQ_CAUSE_MSI_PT_CORRUPTED;
+        } else {
+            cause = RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT;
+        }
+        goto err;
+    }
+
+    le64_to_cpus(&pte[0]);
+    le64_to_cpus(&pte[1]);
+
+    if (!(pte[0] & RISCV_IOMMU_MSI_PTE_V) || (pte[0] & RISCV_IOMMU_MSI_PTE_C)) {
+        /*
+         * The spec mentions that: "If msipte.C == 1, then further
+         * processing to interpret the PTE is implementation
+         * defined.". We'll abort with cause = 262 for this
+         * case too.
+         */
+        res = MEMTX_ACCESS_ERROR;
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_INVALID;
+        goto err;
+    }
+
+    switch (get_field(pte[0], RISCV_IOMMU_MSI_PTE_M)) {
+    case RISCV_IOMMU_MSI_PTE_M_BASIC:
+        /* MSI Pass-through mode */
+        addr = PPN_PHYS(get_field(pte[0], RISCV_IOMMU_MSI_PTE_PPN));
+
+        trace_riscv_iommu_msi(s->parent_obj.id, PCI_BUS_NUM(ctx->devid),
+                              PCI_SLOT(ctx->devid), PCI_FUNC(ctx->devid),
+                              gpa, addr);
+
+        res = dma_memory_write(s->target_as, addr, &data, size, attrs);
+        if (res != MEMTX_OK) {
+            cause = RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT;
+            goto err;
+        }
+
+        return MEMTX_OK;
+    case RISCV_IOMMU_MSI_PTE_M_MRIF:
+        /* MRIF mode, continue. */
+        break;
+    default:
+        res = MEMTX_ACCESS_ERROR;
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_MISCONFIGURED;
+        goto err;
+    }
+
+    /*
+     * Report an error for interrupt identities exceeding the maximum allowed
+     * for an IMSIC interrupt file (2047) or destination address is not 32-bit
+     * aligned. See IOMMU Specification, Chapter 2.3. MSI page tables.
+     */
+    if ((data > 2047) || (gpa & 3)) {
+        res = MEMTX_ACCESS_ERROR;
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_MISCONFIGURED;
+        goto err;
+    }
+
+    /* MSI MRIF mode, non atomic pending bit update */
+
+    /* MRIF pending bit address */
+    addr = get_field(pte[0], RISCV_IOMMU_MSI_PTE_MRIF_ADDR) << 9;
+    addr = addr | ((data & 0x7c0) >> 3);
+
+    trace_riscv_iommu_msi(s->parent_obj.id, PCI_BUS_NUM(ctx->devid),
+                          PCI_SLOT(ctx->devid), PCI_FUNC(ctx->devid),
+                          gpa, addr);
+
+    /* MRIF pending bit mask */
+    data = 1ULL << (data & 0x03f);
+    res = dma_memory_read(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT;
+        goto err;
+    }
+
+    intn = intn | data;
+    res = dma_memory_write(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT;
+        goto err;
+    }
+
+    /* Get MRIF enable bits */
+    addr = addr + sizeof(intn);
+    res = dma_memory_read(s->target_as, addr, &intn, sizeof(intn), attrs);
+    if (res != MEMTX_OK) {
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT;
+        goto err;
+    }
+
+    if (!(intn & data)) {
+        /* notification disabled, MRIF update completed. */
+        return MEMTX_OK;
+    }
+
+    /* Send notification message */
+    addr = PPN_PHYS(get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NPPN));
+    n190 = get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID) |
+          (get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID_MSB) << 10);
+
+    res = dma_memory_write(s->target_as, addr, &n190, sizeof(n190), attrs);
+    if (res != MEMTX_OK) {
+        cause = RISCV_IOMMU_FQ_CAUSE_MSI_WR_FAULT;
+        goto err;
+    }
+
+    trace_riscv_iommu_mrif_notification(s->parent_obj.id, n190, addr);
+
+    return MEMTX_OK;
+
+err:
+    riscv_iommu_report_fault(s, ctx, fault_type, cause,
+                             !!ctx->process_id, 0, 0);
+    return res;
+}
+
+/*
+ * Check device context configuration as described by the
+ * riscv-iommu spec section "Device-context configuration
+ * checks".
+ */
+static bool riscv_iommu_validate_device_ctx(RISCVIOMMUState *s,
+                                            RISCVIOMMUContext *ctx)
+{
+    uint32_t fsc_mode, msi_mode;
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_EN_PRI) &&
+        ctx->tc & RISCV_IOMMU_DC_TC_PRPR) {
+        return false;
+    }
+
+    if (!(s->cap & RISCV_IOMMU_CAP_T2GPA) &&
+        ctx->tc & RISCV_IOMMU_DC_TC_T2GPA) {
+        return false;
+    }
+
+    if (s->cap & RISCV_IOMMU_CAP_MSI_FLAT) {
+        msi_mode = get_field(ctx->msiptp, RISCV_IOMMU_DC_MSIPTP_MODE);
+
+        if (msi_mode != RISCV_IOMMU_DC_MSIPTP_MODE_OFF &&
+            msi_mode != RISCV_IOMMU_DC_MSIPTP_MODE_FLAT) {
+            return false;
+        }
+    }
+
+    fsc_mode = get_field(ctx->satp, RISCV_IOMMU_DC_FSC_MODE);
+
+    if (ctx->tc & RISCV_IOMMU_DC_TC_PDTV) {
+        switch (fsc_mode) {
+        case RISCV_IOMMU_DC_FSC_PDTP_MODE_PD8:
+            if (!(s->cap & RISCV_IOMMU_CAP_PD8)) {
+                return false;
+            }
+            break;
+        case RISCV_IOMMU_DC_FSC_PDTP_MODE_PD17:
+            if (!(s->cap & RISCV_IOMMU_CAP_PD17)) {
+                return false;
+            }
+            break;
+        case RISCV_IOMMU_DC_FSC_PDTP_MODE_PD20:
+            if (!(s->cap & RISCV_IOMMU_CAP_PD20)) {
+                return false;
+            }
+            break;
+        }
+    } else {
+        /* DC.tc.PDTV is 0 */
+        if (ctx->tc & RISCV_IOMMU_DC_TC_DPE) {
+            return false;
+        }
+
+        if (ctx->tc & RISCV_IOMMU_DC_TC_SXL) {
+            if (fsc_mode == RISCV_IOMMU_CAP_SV32 &&
+                !(s->cap & RISCV_IOMMU_CAP_SV32)) {
+                return false;
+            }
+        } else {
+            switch (fsc_mode) {
+            case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV39:
+                if (!(s->cap & RISCV_IOMMU_CAP_SV39)) {
+                    return false;
+                }
+                break;
+            case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV48:
+                if (!(s->cap & RISCV_IOMMU_CAP_SV48)) {
+                    return false;
+                }
+            break;
+            case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57:
+                if (!(s->cap & RISCV_IOMMU_CAP_SV57)) {
+                    return false;
+                }
+                break;
+            }
+        }
+    }
+
+    /*
+     * CAP_END is always zero (only one endianess). FCTL_BE is
+     * always zero (little-endian accesses). Thus TC_SBE must
+     * always be LE, i.e. zero.
+     */
+    if (ctx->tc & RISCV_IOMMU_DC_TC_SBE) {
+        return false;
+    }
+
+    return true;
+}
+
+/*
+ * Validate process context (PC) according to section
+ * "Process-context configuration checks".
+ */
+static bool riscv_iommu_validate_process_ctx(RISCVIOMMUState *s,
+                                             RISCVIOMMUContext *ctx)
+{
+    uint32_t mode;
+
+    if (get_field(ctx->ta, RISCV_IOMMU_PC_TA_RESERVED)) {
+        return false;
+    }
+
+    if (get_field(ctx->satp, RISCV_IOMMU_PC_FSC_RESERVED)) {
+        return false;
+    }
+
+    mode = get_field(ctx->satp, RISCV_IOMMU_DC_FSC_MODE);
+    switch (mode) {
+    case RISCV_IOMMU_DC_FSC_MODE_BARE:
+    /* sv39 and sv32 modes have the same value (8) */
+    case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV39:
+    case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV48:
+    case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57:
+        break;
+    default:
+        return false;
+    }
+
+    if (ctx->tc & RISCV_IOMMU_DC_TC_SXL) {
+        if (mode == RISCV_IOMMU_CAP_SV32 &&
+            !(s->cap & RISCV_IOMMU_CAP_SV32)) {
+                return false;
+        }
+    } else {
+        switch (mode) {
+        case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV39:
+            if (!(s->cap & RISCV_IOMMU_CAP_SV39)) {
+                return false;
+            }
+            break;
+        case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV48:
+            if (!(s->cap & RISCV_IOMMU_CAP_SV48)) {
+                return false;
+            }
+            break;
+        case RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57:
+            if (!(s->cap & RISCV_IOMMU_CAP_SV57)) {
+                return false;
+            }
+            break;
+        }
+    }
+
+    return true;
+}
+
+/*
+ * RISC-V IOMMU Device Context Loopkup - Device Directory Tree Walk
+ *
+ * @s         : IOMMU Device State
+ * @ctx       : Device Translation Context with devid and process_id set.
+ * @return    : success or fault code.
+ */
+static int riscv_iommu_ctx_fetch(RISCVIOMMUState *s, RISCVIOMMUContext *ctx)
+{
+    const uint64_t ddtp = s->ddtp;
+    unsigned mode = get_field(ddtp, RISCV_IOMMU_DDTP_MODE);
+    dma_addr_t addr = PPN_PHYS(get_field(ddtp, RISCV_IOMMU_DDTP_PPN));
+    struct riscv_iommu_dc dc;
+    /* Device Context format: 0: extended (64 bytes) | 1: base (32 bytes) */
+    const int dc_fmt = !s->enable_msi;
+    const size_t dc_len = sizeof(dc) >> dc_fmt;
+    unsigned depth;
+    uint64_t de;
+
+    switch (mode) {
+    case RISCV_IOMMU_DDTP_MODE_OFF:
+        return RISCV_IOMMU_FQ_CAUSE_DMA_DISABLED;
+
+    case RISCV_IOMMU_DDTP_MODE_BARE:
+        /* mock up pass-through translation context */
+        ctx->gatp = set_field(0, RISCV_IOMMU_ATP_MODE_FIELD,
+            RISCV_IOMMU_DC_IOHGATP_MODE_BARE);
+        ctx->satp = set_field(0, RISCV_IOMMU_ATP_MODE_FIELD,
+            RISCV_IOMMU_DC_FSC_MODE_BARE);
+        ctx->tc = RISCV_IOMMU_DC_TC_V;
+        ctx->ta = 0;
+        ctx->msiptp = 0;
+        return 0;
+
+    case RISCV_IOMMU_DDTP_MODE_1LVL:
+        depth = 0;
+        break;
+
+    case RISCV_IOMMU_DDTP_MODE_2LVL:
+        depth = 1;
+        break;
+
+    case RISCV_IOMMU_DDTP_MODE_3LVL:
+        depth = 2;
+        break;
+
+    default:
+        return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+    }
+
+    /*
+     * Check supported device id width (in bits).
+     * See IOMMU Specification, Chapter 6. Software guidelines.
+     * - if extended device-context format is used:
+     *   1LVL: 6, 2LVL: 15, 3LVL: 24
+     * - if base device-context format is used:
+     *   1LVL: 7, 2LVL: 16, 3LVL: 24
+     */
+    if (ctx->devid >= (1 << (depth * 9 + 6 + (dc_fmt && depth != 2)))) {
+        return RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED;
+    }
+
+    /* Device directory tree walk */
+    for (; depth-- > 0; ) {
+        /*
+         * Select device id index bits based on device directory tree level
+         * and device context format.
+         * See IOMMU Specification, Chapter 2. Data Structures.
+         * - if extended device-context format is used:
+         *   device index: [23:15][14:6][5:0]
+         * - if base device-context format is used:
+         *   device index: [23:16][15:7][6:0]
+         */
+        const int split = depth * 9 + 6 + dc_fmt;
+        addr |= ((ctx->devid >> split) << 3) & ~TARGET_PAGE_MASK;
+        if (dma_memory_read(s->target_as, addr, &de, sizeof(de),
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            return RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT;
+        }
+        le64_to_cpus(&de);
+        if (!(de & RISCV_IOMMU_DDTE_VALID)) {
+            /* invalid directory entry */
+            return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+        }
+        if (de & ~(RISCV_IOMMU_DDTE_PPN | RISCV_IOMMU_DDTE_VALID)) {
+            /* reserved bits set */
+            return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+        }
+        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_DDTE_PPN));
+    }
+
+    /* index into device context entry page */
+    addr |= (ctx->devid * dc_len) & ~TARGET_PAGE_MASK;
+
+    memset(&dc, 0, sizeof(dc));
+    if (dma_memory_read(s->target_as, addr, &dc, dc_len,
+                        MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_LOAD_FAULT;
+    }
+
+    /* Set translation context. */
+    ctx->tc = le64_to_cpu(dc.tc);
+    ctx->gatp = le64_to_cpu(dc.iohgatp);
+    ctx->satp = le64_to_cpu(dc.fsc);
+    ctx->ta = le64_to_cpu(dc.ta);
+    ctx->msiptp = le64_to_cpu(dc.msiptp);
+    ctx->msi_addr_mask = le64_to_cpu(dc.msi_addr_mask);
+    ctx->msi_addr_pattern = le64_to_cpu(dc.msi_addr_pattern);
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_V)) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+    }
+
+    if (!riscv_iommu_validate_device_ctx(s, ctx)) {
+        return RISCV_IOMMU_FQ_CAUSE_DDT_MISCONFIGURED;
+    }
+
+    /* FSC field checks */
+    mode = get_field(ctx->satp, RISCV_IOMMU_DC_FSC_MODE);
+    addr = PPN_PHYS(get_field(ctx->satp, RISCV_IOMMU_DC_FSC_PPN));
+
+    if (!(ctx->tc & RISCV_IOMMU_DC_TC_PDTV)) {
+        if (ctx->process_id != RISCV_IOMMU_NOPROCID) {
+            /* PID is disabled */
+            return RISCV_IOMMU_FQ_CAUSE_TTYPE_BLOCKED;
+        }
+        if (mode > RISCV_IOMMU_DC_FSC_IOSATP_MODE_SV57) {
+            /* Invalid translation mode */
+            return RISCV_IOMMU_FQ_CAUSE_DDT_INVALID;
+        }
+        return 0;
+    }
+
+    if (ctx->process_id == RISCV_IOMMU_NOPROCID) {
+        if (!(ctx->tc & RISCV_IOMMU_DC_TC_DPE)) {
+            /* No default process_id enabled, set BARE mode */
+            ctx->satp = 0ULL;
+            return 0;
+        } else {
+            /* Use default process_id #0 */
+            ctx->process_id = 0;
+        }
+    }
+
+    if (mode == RISCV_IOMMU_DC_FSC_MODE_BARE) {
+        /* No S-Stage translation, done. */
+        return 0;
+    }
+
+    /* FSC.TC.PDTV enabled */
+    if (mode > RISCV_IOMMU_DC_FSC_PDTP_MODE_PD20) {
+        /* Invalid PDTP.MODE */
+        return RISCV_IOMMU_FQ_CAUSE_PDT_MISCONFIGURED;
+    }
+
+    for (depth = mode - RISCV_IOMMU_DC_FSC_PDTP_MODE_PD8; depth-- > 0; ) {
+        /*
+         * Select process id index bits based on process directory tree
+         * level. See IOMMU Specification, 2.2. Process-Directory-Table.
+         */
+        const int split = depth * 9 + 8;
+        addr |= ((ctx->process_id >> split) << 3) & ~TARGET_PAGE_MASK;
+        if (dma_memory_read(s->target_as, addr, &de, sizeof(de),
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
+        }
+        le64_to_cpus(&de);
+        if (!(de & RISCV_IOMMU_PC_TA_V)) {
+            return RISCV_IOMMU_FQ_CAUSE_PDT_INVALID;
+        }
+        addr = PPN_PHYS(get_field(de, RISCV_IOMMU_PC_FSC_PPN));
+    }
+
+    /* Leaf entry in PDT */
+    addr |= (ctx->process_id << 4) & ~TARGET_PAGE_MASK;
+    if (dma_memory_read(s->target_as, addr, &dc.ta, sizeof(uint64_t) * 2,
+                        MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        return RISCV_IOMMU_FQ_CAUSE_PDT_LOAD_FAULT;
+    }
+
+    /* Use FSC and TA from process directory entry. */
+    ctx->ta = le64_to_cpu(dc.ta);
+    ctx->satp = le64_to_cpu(dc.fsc);
+
+    if (!(ctx->ta & RISCV_IOMMU_PC_TA_V)) {
+        return RISCV_IOMMU_FQ_CAUSE_PDT_INVALID;
+    }
+
+    if (!riscv_iommu_validate_process_ctx(s, ctx)) {
+        return RISCV_IOMMU_FQ_CAUSE_PDT_MISCONFIGURED;
+    }
+
+    return 0;
+}
+
+/* Translation Context cache support */
+static gboolean __ctx_equal(gconstpointer v1, gconstpointer v2)
+{
+    RISCVIOMMUContext *c1 = (RISCVIOMMUContext *) v1;
+    RISCVIOMMUContext *c2 = (RISCVIOMMUContext *) v2;
+    return c1->devid == c2->devid &&
+           c1->process_id == c2->process_id;
+}
+
+static guint __ctx_hash(gconstpointer v)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) v;
+    /*
+     * Generate simple hash of (process_id, devid)
+     * assuming 24-bit wide devid.
+     */
+    return (guint)(ctx->devid) + ((guint)(ctx->process_id) << 24);
+}
+
+static void __ctx_inval_devid_procid(gpointer key, gpointer value,
+                                     gpointer data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    RISCVIOMMUContext *arg = (RISCVIOMMUContext *) data;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V &&
+        ctx->devid == arg->devid &&
+        ctx->process_id == arg->process_id) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void __ctx_inval_devid(gpointer key, gpointer value, gpointer data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    RISCVIOMMUContext *arg = (RISCVIOMMUContext *) data;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V &&
+        ctx->devid == arg->devid) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void __ctx_inval_all(gpointer key, gpointer value, gpointer data)
+{
+    RISCVIOMMUContext *ctx = (RISCVIOMMUContext *) value;
+    if (ctx->tc & RISCV_IOMMU_DC_TC_V) {
+        ctx->tc &= ~RISCV_IOMMU_DC_TC_V;
+    }
+}
+
+static void riscv_iommu_ctx_inval(RISCVIOMMUState *s, GHFunc func,
+                                  uint32_t devid, uint32_t process_id)
+{
+    GHashTable *ctx_cache;
+    RISCVIOMMUContext key = {
+        .devid = devid,
+        .process_id = process_id,
+    };
+    ctx_cache = g_hash_table_ref(s->ctx_cache);
+    qemu_mutex_lock(&s->ctx_lock);
+    g_hash_table_foreach(ctx_cache, func, &key);
+    qemu_mutex_unlock(&s->ctx_lock);
+    g_hash_table_unref(ctx_cache);
+}
+
+/* Find or allocate translation context for a given {device_id, process_id} */
+static RISCVIOMMUContext *riscv_iommu_ctx(RISCVIOMMUState *s,
+                                          unsigned devid, unsigned process_id,
+                                          void **ref)
+{
+    GHashTable *ctx_cache;
+    RISCVIOMMUContext *ctx;
+    RISCVIOMMUContext key = {
+        .devid = devid,
+        .process_id = process_id,
+    };
+
+    ctx_cache = g_hash_table_ref(s->ctx_cache);
+    qemu_mutex_lock(&s->ctx_lock);
+    ctx = g_hash_table_lookup(ctx_cache, &key);
+    qemu_mutex_unlock(&s->ctx_lock);
+
+    if (ctx && (ctx->tc & RISCV_IOMMU_DC_TC_V)) {
+        *ref = ctx_cache;
+        return ctx;
+    }
+
+    ctx = g_new0(RISCVIOMMUContext, 1);
+    ctx->devid = devid;
+    ctx->process_id = process_id;
+
+    int fault = riscv_iommu_ctx_fetch(s, ctx);
+    if (!fault) {
+        qemu_mutex_lock(&s->ctx_lock);
+        if (g_hash_table_size(ctx_cache) >= LIMIT_CACHE_CTX) {
+            g_hash_table_unref(ctx_cache);
+            ctx_cache = g_hash_table_new_full(__ctx_hash, __ctx_equal,
+                                              g_free, NULL);
+            g_hash_table_ref(ctx_cache);
+            g_hash_table_unref(qatomic_xchg(&s->ctx_cache, ctx_cache));
+        }
+        g_hash_table_add(ctx_cache, ctx);
+        qemu_mutex_unlock(&s->ctx_lock);
+        *ref = ctx_cache;
+        return ctx;
+    }
+
+    g_hash_table_unref(ctx_cache);
+    *ref = NULL;
+
+    riscv_iommu_report_fault(s, ctx, RISCV_IOMMU_FQ_TTYPE_UADDR_RD,
+                             fault, !!process_id, 0, 0);
+
+    g_free(ctx);
+    return NULL;
+}
+
+static void riscv_iommu_ctx_put(RISCVIOMMUState *s, void *ref)
+{
+    if (ref) {
+        g_hash_table_unref((GHashTable *)ref);
+    }
+}
+
+/* Find or allocate address space for a given device */
+static AddressSpace *riscv_iommu_space(RISCVIOMMUState *s, uint32_t devid)
+{
+    RISCVIOMMUSpace *as;
+
+    /* FIXME: PCIe bus remapping for attached endpoints. */
+    devid |= s->bus << 8;
+
+    qemu_mutex_lock(&s->core_lock);
+    QLIST_FOREACH(as, &s->spaces, list) {
+        if (as->devid == devid) {
+            break;
+        }
+    }
+    qemu_mutex_unlock(&s->core_lock);
+
+    if (as == NULL) {
+        char name[64];
+        as = g_new0(RISCVIOMMUSpace, 1);
+
+        as->iommu = s;
+        as->devid = devid;
+
+        snprintf(name, sizeof(name), "riscv-iommu-%04x:%02x.%d-iova",
+            PCI_BUS_NUM(as->devid), PCI_SLOT(as->devid), PCI_FUNC(as->devid));
+
+        /* IOVA address space, untranslated addresses */
+        memory_region_init_iommu(&as->iova_mr, sizeof(as->iova_mr),
+            TYPE_RISCV_IOMMU_MEMORY_REGION,
+            OBJECT(as), "riscv_iommu", UINT64_MAX);
+        address_space_init(&as->iova_as, MEMORY_REGION(&as->iova_mr), name);
+
+        qemu_mutex_lock(&s->core_lock);
+        QLIST_INSERT_HEAD(&s->spaces, as, list);
+        qemu_mutex_unlock(&s->core_lock);
+
+        trace_riscv_iommu_new(s->parent_obj.id, PCI_BUS_NUM(as->devid),
+                PCI_SLOT(as->devid), PCI_FUNC(as->devid));
+    }
+    return &as->iova_as;
+}
+
+static int riscv_iommu_translate(RISCVIOMMUState *s, RISCVIOMMUContext *ctx,
+    IOMMUTLBEntry *iotlb)
+{
+    bool enable_pid;
+    bool enable_pri;
+    int fault;
+
+    /*
+     * TC[32] is reserved for custom extensions, used here to temporarily
+     * enable automatic page-request generation for ATS queries.
+     */
+    enable_pri = (iotlb->perm == IOMMU_NONE) && (ctx->tc & BIT_ULL(32));
+    enable_pid = (ctx->tc & RISCV_IOMMU_DC_TC_PDTV);
+
+    /* Translate using device directory / page table information. */
+    fault = riscv_iommu_spa_fetch(s, ctx, iotlb);
+
+    if (enable_pri && fault) {
+        struct riscv_iommu_pq_record pr = {0};
+        if (enable_pid) {
+            pr.hdr = set_field(RISCV_IOMMU_PREQ_HDR_PV,
+                               RISCV_IOMMU_PREQ_HDR_PID, ctx->process_id);
+        }
+        pr.hdr = set_field(pr.hdr, RISCV_IOMMU_PREQ_HDR_DID, ctx->devid);
+        pr.payload = (iotlb->iova & TARGET_PAGE_MASK) |
+                     RISCV_IOMMU_PREQ_PAYLOAD_M;
+        riscv_iommu_pri(s, &pr);
+        return fault;
+    }
+
+    if (fault) {
+        unsigned ttype;
+
+        if (iotlb->perm & IOMMU_RW) {
+            ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_WR;
+        } else {
+            ttype = RISCV_IOMMU_FQ_TTYPE_UADDR_RD;
+        }
+
+        riscv_iommu_report_fault(s, ctx, ttype, fault, enable_pid,
+                                 iotlb->iova, iotlb->translated_addr);
+        return fault;
+    }
+
+    return 0;
+}
+
+/* IOMMU Command Interface */
+static MemTxResult riscv_iommu_iofence(RISCVIOMMUState *s, bool notify,
+    uint64_t addr, uint32_t data)
+{
+    /*
+     * ATS processing in this implementation of the IOMMU is synchronous,
+     * no need to wait for completions here.
+     */
+    if (!notify) {
+        return MEMTX_OK;
+    }
+
+    return dma_memory_write(s->target_as, addr, &data, sizeof(data),
+        MEMTXATTRS_UNSPECIFIED);
+}
+
+static void riscv_iommu_process_ddtp(RISCVIOMMUState *s)
+{
+    uint64_t old_ddtp = s->ddtp;
+    uint64_t new_ddtp = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_DDTP);
+    unsigned new_mode = get_field(new_ddtp, RISCV_IOMMU_DDTP_MODE);
+    unsigned old_mode = get_field(old_ddtp, RISCV_IOMMU_DDTP_MODE);
+    bool ok = false;
+
+    /*
+     * Check for allowed DDTP.MODE transitions:
+     * {OFF, BARE}        -> {OFF, BARE, 1LVL, 2LVL, 3LVL}
+     * {1LVL, 2LVL, 3LVL} -> {OFF, BARE}
+     */
+    if (new_mode == old_mode ||
+        new_mode == RISCV_IOMMU_DDTP_MODE_OFF ||
+        new_mode == RISCV_IOMMU_DDTP_MODE_BARE) {
+        ok = true;
+    } else if (new_mode == RISCV_IOMMU_DDTP_MODE_1LVL ||
+               new_mode == RISCV_IOMMU_DDTP_MODE_2LVL ||
+               new_mode == RISCV_IOMMU_DDTP_MODE_3LVL) {
+        ok = old_mode == RISCV_IOMMU_DDTP_MODE_OFF ||
+             old_mode == RISCV_IOMMU_DDTP_MODE_BARE;
+    }
+
+    if (ok) {
+        /* clear reserved and busy bits, report back sanitized version */
+        new_ddtp = set_field(new_ddtp & RISCV_IOMMU_DDTP_PPN,
+                             RISCV_IOMMU_DDTP_MODE, new_mode);
+    } else {
+        new_ddtp = old_ddtp;
+    }
+    s->ddtp = new_ddtp;
+
+    riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_DDTP, new_ddtp);
+}
+
+/* Command function and opcode field. */
+#define RISCV_IOMMU_CMD(func, op) (((func) << 7) | (op))
+
+static void riscv_iommu_process_cq_tail(RISCVIOMMUState *s)
+{
+    struct riscv_iommu_command cmd;
+    MemTxResult res;
+    dma_addr_t addr;
+    uint32_t tail, head, ctrl;
+    uint64_t cmd_opcode;
+    GHFunc func;
+
+    ctrl = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    tail = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQT) & s->cq_mask;
+    head = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQH) & s->cq_mask;
+
+    /* Check for pending error or queue processing disabled */
+    if (!(ctrl & RISCV_IOMMU_CQCSR_CQON) ||
+        !!(ctrl & (RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CQMF))) {
+        return;
+    }
+
+    while (tail != head) {
+        addr = s->cq_addr  + head * sizeof(cmd);
+        res = dma_memory_read(s->target_as, addr, &cmd, sizeof(cmd),
+                              MEMTXATTRS_UNSPECIFIED);
+
+        if (res != MEMTX_OK) {
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                  RISCV_IOMMU_CQCSR_CQMF, 0);
+            goto fault;
+        }
+
+        trace_riscv_iommu_cmd(s->parent_obj.id, cmd.dword0, cmd.dword1);
+
+        cmd_opcode = get_field(cmd.dword0,
+                               RISCV_IOMMU_CMD_OPCODE | RISCV_IOMMU_CMD_FUNC);
+
+        switch (cmd_opcode) {
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOFENCE_FUNC_C,
+                             RISCV_IOMMU_CMD_IOFENCE_OPCODE):
+            res = riscv_iommu_iofence(s,
+                cmd.dword0 & RISCV_IOMMU_CMD_IOFENCE_AV, cmd.dword1,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IOFENCE_DATA));
+
+            if (res != MEMTX_OK) {
+                riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                                      RISCV_IOMMU_CQCSR_CQMF, 0);
+                goto fault;
+            }
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            if (cmd.dword0 & RISCV_IOMMU_CMD_IOTINVAL_PSCV) {
+                /* illegal command arguments IOTINVAL.GVMA & PSCV == 1 */
+                goto cmd_ill;
+            }
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA,
+                             RISCV_IOMMU_CMD_IOTINVAL_OPCODE):
+            /* translation cache not implemented yet */
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_DDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* invalidate all device context cache mappings */
+                func = __ctx_inval_all;
+            } else {
+                /* invalidate all device context matching DID */
+                func = __ctx_inval_devid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID), 0);
+            break;
+
+        case RISCV_IOMMU_CMD(RISCV_IOMMU_CMD_IODIR_FUNC_INVAL_PDT,
+                             RISCV_IOMMU_CMD_IODIR_OPCODE):
+            if (!(cmd.dword0 & RISCV_IOMMU_CMD_IODIR_DV)) {
+                /* illegal command arguments IODIR_PDT & DV == 0 */
+                goto cmd_ill;
+            } else {
+                func = __ctx_inval_devid_procid;
+            }
+            riscv_iommu_ctx_inval(s, func,
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_DID),
+                get_field(cmd.dword0, RISCV_IOMMU_CMD_IODIR_PID));
+            break;
+
+        default:
+        cmd_ill:
+            /* Invalid instruction, do not advance instruction index. */
+            riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR,
+                RISCV_IOMMU_CQCSR_CMD_ILL, 0);
+            goto fault;
+        }
+
+        /* Advance and update head pointer after command completes. */
+        head = (head + 1) & s->cq_mask;
+        riscv_iommu_reg_set32(s, RISCV_IOMMU_REG_CQH, head);
+    }
+    return;
+
+fault:
+    if (ctrl & RISCV_IOMMU_CQCSR_CIE) {
+        riscv_iommu_notify(s, RISCV_IOMMU_INTR_CQ);
+    }
+}
+
+static void riscv_iommu_process_cq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_CQCSR_CQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_CQB);
+        s->cq_mask = (2ULL << get_field(base, RISCV_IOMMU_CQB_LOG2SZ)) - 1;
+        s->cq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_CQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~s->cq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_CQT], 0);
+        ctrl_set = RISCV_IOMMU_CQCSR_CQON;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQMF |
+                   RISCV_IOMMU_CQCSR_CMD_ILL | RISCV_IOMMU_CQCSR_CMD_TO |
+                   RISCV_IOMMU_CQCSR_FENCE_W_IP;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQT], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY | RISCV_IOMMU_CQCSR_CQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_CQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_CQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_fq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_FQCSR_FQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_FQB);
+        s->fq_mask = (2ULL << get_field(base, RISCV_IOMMU_FQB_LOG2SZ)) - 1;
+        s->fq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_FQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~s->fq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_FQT], 0);
+        ctrl_set = RISCV_IOMMU_FQCSR_FQON;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQMF |
+            RISCV_IOMMU_FQCSR_FQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY | RISCV_IOMMU_FQCSR_FQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_FQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_FQCSR, ctrl_set, ctrl_clr);
+}
+
+static void riscv_iommu_process_pq_control(RISCVIOMMUState *s)
+{
+    uint64_t base;
+    uint32_t ctrl_set = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+    uint32_t ctrl_clr;
+    bool enable = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQEN);
+    bool active = !!(ctrl_set & RISCV_IOMMU_PQCSR_PQON);
+
+    if (enable && !active) {
+        base = riscv_iommu_reg_get64(s, RISCV_IOMMU_REG_PQB);
+        s->pq_mask = (2ULL << get_field(base, RISCV_IOMMU_PQB_LOG2SZ)) - 1;
+        s->pq_addr = PPN_PHYS(get_field(base, RISCV_IOMMU_PQB_PPN));
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~s->pq_mask);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQH], 0);
+        stl_le_p(&s->regs_rw[RISCV_IOMMU_REG_PQT], 0);
+        ctrl_set = RISCV_IOMMU_PQCSR_PQON;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQMF |
+            RISCV_IOMMU_PQCSR_PQOF;
+    } else if (!enable && active) {
+        stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQH], ~0);
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY | RISCV_IOMMU_PQCSR_PQON;
+    } else {
+        ctrl_set = 0;
+        ctrl_clr = RISCV_IOMMU_PQCSR_BUSY;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_PQCSR, ctrl_set, ctrl_clr);
+}
+
+typedef void riscv_iommu_process_fn(RISCVIOMMUState *s);
+
+static void riscv_iommu_update_icvec(RISCVIOMMUState *s, uint64_t data)
+{
+    uint64_t icvec = 0;
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_CIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_CIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_FIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_FIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_PMIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_PMIV);
+
+    icvec |= MIN(data & RISCV_IOMMU_ICVEC_PIV,
+                 s->icvec_avail_vectors & RISCV_IOMMU_ICVEC_PIV);
+
+    trace_riscv_iommu_icvec_write(data, icvec);
+
+    riscv_iommu_reg_set64(s, RISCV_IOMMU_REG_ICVEC, icvec);
+}
+
+static void riscv_iommu_update_ipsr(RISCVIOMMUState *s, uint64_t data)
+{
+    uint32_t cqcsr, fqcsr, pqcsr;
+    uint32_t ipsr_set = 0;
+    uint32_t ipsr_clr = 0;
+
+    if (data & RISCV_IOMMU_IPSR_CIP) {
+        cqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_CQCSR);
+
+        if (cqcsr & RISCV_IOMMU_CQCSR_CIE &&
+            (cqcsr & RISCV_IOMMU_CQCSR_FENCE_W_IP ||
+             cqcsr & RISCV_IOMMU_CQCSR_CMD_ILL ||
+             cqcsr & RISCV_IOMMU_CQCSR_CMD_TO ||
+             cqcsr & RISCV_IOMMU_CQCSR_CQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_CIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_CIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_CIP;
+    }
+
+    if (data & RISCV_IOMMU_IPSR_FIP) {
+        fqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_FQCSR);
+
+        if (fqcsr & RISCV_IOMMU_FQCSR_FIE &&
+            (fqcsr & RISCV_IOMMU_FQCSR_FQOF ||
+             fqcsr & RISCV_IOMMU_FQCSR_FQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_FIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_FIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_FIP;
+    }
+
+    if (data & RISCV_IOMMU_IPSR_PIP) {
+        pqcsr = riscv_iommu_reg_get32(s, RISCV_IOMMU_REG_PQCSR);
+
+        if (pqcsr & RISCV_IOMMU_PQCSR_PIE &&
+            (pqcsr & RISCV_IOMMU_PQCSR_PQOF ||
+             pqcsr & RISCV_IOMMU_PQCSR_PQMF)) {
+            ipsr_set |= RISCV_IOMMU_IPSR_PIP;
+        } else {
+            ipsr_clr |= RISCV_IOMMU_IPSR_PIP;
+        }
+    } else {
+        ipsr_clr |= RISCV_IOMMU_IPSR_PIP;
+    }
+
+    riscv_iommu_reg_mod32(s, RISCV_IOMMU_REG_IPSR, ipsr_set, ipsr_clr);
+}
+
+static MemTxResult riscv_iommu_mmio_write(void *opaque, hwaddr addr,
+    uint64_t data, unsigned size, MemTxAttrs attrs)
+{
+    riscv_iommu_process_fn *process_fn = NULL;
+    RISCVIOMMUState *s = opaque;
+    uint32_t regb = addr & ~3;
+    uint32_t busy = 0;
+    uint64_t val = 0;
+
+    if ((addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment or access size */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        /* Unsupported MMIO access location. */
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* Track actionable MMIO write. */
+    switch (regb) {
+    case RISCV_IOMMU_REG_DDTP:
+    case RISCV_IOMMU_REG_DDTP + 4:
+        process_fn = riscv_iommu_process_ddtp;
+        regb = RISCV_IOMMU_REG_DDTP;
+        busy = RISCV_IOMMU_DDTP_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_CQT:
+        process_fn = riscv_iommu_process_cq_tail;
+        break;
+
+    case RISCV_IOMMU_REG_CQCSR:
+        process_fn = riscv_iommu_process_cq_control;
+        busy = RISCV_IOMMU_CQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_FQCSR:
+        process_fn = riscv_iommu_process_fq_control;
+        busy = RISCV_IOMMU_FQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_PQCSR:
+        process_fn = riscv_iommu_process_pq_control;
+        busy = RISCV_IOMMU_PQCSR_BUSY;
+        break;
+
+    case RISCV_IOMMU_REG_ICVEC:
+    case RISCV_IOMMU_REG_IPSR:
+        /*
+         * ICVEC and IPSR have special read/write procedures. We'll
+         * call their respective helpers and exit.
+         */
+        qemu_spin_lock(&s->regs_lock);
+
+        if (size == 4) {
+            uint32_t ro = ldl_le_p(&s->regs_ro[addr]);
+            uint32_t wc = ldl_le_p(&s->regs_wc[addr]);
+            uint32_t rw = ldl_le_p(&s->regs_rw[addr]);
+            stl_le_p(&val, ((rw & ro) | (data & ~ro)) & ~(data & wc));
+        } else if (size == 8) {
+            uint64_t ro = ldq_le_p(&s->regs_ro[addr]);
+            uint64_t wc = ldq_le_p(&s->regs_wc[addr]);
+            uint64_t rw = ldq_le_p(&s->regs_rw[addr]);
+            stq_le_p(&val, ((rw & ro) | (data & ~ro)) & ~(data & wc));
+        }
+
+        qemu_spin_unlock(&s->regs_lock);
+
+        if (regb == RISCV_IOMMU_REG_ICVEC) {
+            riscv_iommu_update_icvec(s, val);
+        } else {
+            riscv_iommu_update_ipsr(s, val);
+        }
+
+        return MEMTX_OK;
+
+    default:
+        break;
+    }
+
+    /*
+     * Registers update might be not synchronized with core logic.
+     * If system software updates register when relevant BUSY bit
+     * is set IOMMU behavior of additional writes to the register
+     * is UNSPECIFIED.
+     */
+    qemu_spin_lock(&s->regs_lock);
+    if (size == 1) {
+        uint8_t ro = s->regs_ro[addr];
+        uint8_t wc = s->regs_wc[addr];
+        uint8_t rw = s->regs_rw[addr];
+        s->regs_rw[addr] = ((rw & ro) | (data & ~ro)) & ~(data & wc);
+    } else if (size == 2) {
+        uint16_t ro = lduw_le_p(&s->regs_ro[addr]);
+        uint16_t wc = lduw_le_p(&s->regs_wc[addr]);
+        uint16_t rw = lduw_le_p(&s->regs_rw[addr]);
+        stw_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    } else if (size == 4) {
+        uint32_t ro = ldl_le_p(&s->regs_ro[addr]);
+        uint32_t wc = ldl_le_p(&s->regs_wc[addr]);
+        uint32_t rw = ldl_le_p(&s->regs_rw[addr]);
+        stl_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    } else if (size == 8) {
+        uint64_t ro = ldq_le_p(&s->regs_ro[addr]);
+        uint64_t wc = ldq_le_p(&s->regs_wc[addr]);
+        uint64_t rw = ldq_le_p(&s->regs_rw[addr]);
+        stq_le_p(&s->regs_rw[addr], ((rw & ro) | (data & ~ro)) & ~(data & wc));
+    }
+
+    /* Busy flag update, MSB 4-byte register. */
+    if (busy) {
+        uint32_t rw = ldl_le_p(&s->regs_rw[regb]);
+        stl_le_p(&s->regs_rw[regb], rw | busy);
+    }
+    qemu_spin_unlock(&s->regs_lock);
+
+    if (process_fn) {
+        qemu_mutex_lock(&s->core_lock);
+        process_fn(s);
+        qemu_mutex_unlock(&s->core_lock);
+    }
+
+    return MEMTX_OK;
+}
+
+static MemTxResult riscv_iommu_mmio_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState *s = opaque;
+    uint64_t val = -1;
+    uint8_t *ptr;
+
+    if ((addr & (size - 1)) != 0) {
+        /* Unsupported MMIO alignment. */
+        return MEMTX_ERROR;
+    }
+
+    if (addr + size > RISCV_IOMMU_REG_MSI_CONFIG) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    ptr = &s->regs_rw[addr];
+
+    if (size == 1) {
+        val = (uint64_t)*ptr;
+    } else if (size == 2) {
+        val = lduw_le_p(ptr);
+    } else if (size == 4) {
+        val = ldl_le_p(ptr);
+    } else if (size == 8) {
+        val = ldq_le_p(ptr);
+    } else {
+        return MEMTX_ERROR;
+    }
+
+    *data = val;
+
+    return MEMTX_OK;
+}
+
+static const MemoryRegionOps riscv_iommu_mmio_ops = {
+    .read_with_attrs = riscv_iommu_mmio_read,
+    .write_with_attrs = riscv_iommu_mmio_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+        .unaligned = false,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+    }
+};
+
+/*
+ * Translations matching MSI pattern check are redirected to "riscv-iommu-trap"
+ * memory region as untranslated address, for additional MSI/MRIF interception
+ * by IOMMU interrupt remapping implementation.
+ * Note: Device emulation code generating an MSI is expected to provide a valid
+ * memory transaction attributes with requested_id set.
+ */
+static MemTxResult riscv_iommu_trap_write(void *opaque, hwaddr addr,
+    uint64_t data, unsigned size, MemTxAttrs attrs)
+{
+    RISCVIOMMUState* s = (RISCVIOMMUState *)opaque;
+    RISCVIOMMUContext *ctx;
+    MemTxResult res;
+    void *ref;
+    uint32_t devid = attrs.requester_id;
+
+    if (attrs.unspecified) {
+        return MEMTX_ACCESS_ERROR;
+    }
+
+    /* FIXME: PCIe bus remapping for attached endpoints. */
+    devid |= s->bus << 8;
+
+    ctx = riscv_iommu_ctx(s, devid, 0, &ref);
+    if (ctx == NULL) {
+        res = MEMTX_ACCESS_ERROR;
+    } else {
+        res = riscv_iommu_msi_write(s, ctx, addr, data, size, attrs);
+    }
+    riscv_iommu_ctx_put(s, ref);
+    return res;
+}
+
+static MemTxResult riscv_iommu_trap_read(void *opaque, hwaddr addr,
+    uint64_t *data, unsigned size, MemTxAttrs attrs)
+{
+    return MEMTX_ACCESS_ERROR;
+}
+
+static const MemoryRegionOps riscv_iommu_trap_ops = {
+    .read_with_attrs = riscv_iommu_trap_read,
+    .write_with_attrs = riscv_iommu_trap_write,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+        .unaligned = true,
+    },
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 8,
+    }
+};
+
+static void riscv_iommu_realize(DeviceState *dev, Error **errp)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    s->cap = s->version & RISCV_IOMMU_CAP_VERSION;
+    if (s->enable_msi) {
+        s->cap |= RISCV_IOMMU_CAP_MSI_FLAT | RISCV_IOMMU_CAP_MSI_MRIF;
+    }
+    if (s->enable_s_stage) {
+        s->cap |= RISCV_IOMMU_CAP_SV32 | RISCV_IOMMU_CAP_SV39 |
+                  RISCV_IOMMU_CAP_SV48 | RISCV_IOMMU_CAP_SV57;
+    }
+    if (s->enable_g_stage) {
+        s->cap |= RISCV_IOMMU_CAP_SV32X4 | RISCV_IOMMU_CAP_SV39X4 |
+                  RISCV_IOMMU_CAP_SV48X4 | RISCV_IOMMU_CAP_SV57X4;
+    }
+    /* Report QEMU target physical address space limits */
+    s->cap = set_field(s->cap, RISCV_IOMMU_CAP_PAS,
+                       TARGET_PHYS_ADDR_SPACE_BITS);
+
+    /* TODO: method to report supported PID bits */
+    s->pid_bits = 8; /* restricted to size of MemTxAttrs.pid */
+    s->cap |= RISCV_IOMMU_CAP_PD8;
+
+    /* Out-of-reset translation mode: OFF (DMA disabled) BARE (passthrough) */
+    s->ddtp = set_field(0, RISCV_IOMMU_DDTP_MODE, s->enable_off ?
+                        RISCV_IOMMU_DDTP_MODE_OFF : RISCV_IOMMU_DDTP_MODE_BARE);
+
+    /* register storage */
+    s->regs_rw = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_ro = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+    s->regs_wc = g_new0(uint8_t, RISCV_IOMMU_REG_SIZE);
+
+     /* Mark all registers read-only */
+    memset(s->regs_ro, 0xff, RISCV_IOMMU_REG_SIZE);
+
+    /*
+     * Register complete MMIO space, including MSI/PBA registers.
+     * Note, PCIDevice implementation will add overlapping MR for MSI/PBA,
+     * managed directly by the PCIDevice implementation.
+     */
+    memory_region_init_io(&s->regs_mr, OBJECT(dev), &riscv_iommu_mmio_ops, s,
+        "riscv-iommu-regs", RISCV_IOMMU_REG_SIZE);
+
+    /* Set power-on register state */
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_CAP], s->cap);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_FCTL], 0);
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_FCTL],
+             ~(RISCV_IOMMU_FCTL_BE | RISCV_IOMMU_FCTL_WSI));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_DDTP],
+        ~(RISCV_IOMMU_DDTP_PPN | RISCV_IOMMU_DDTP_MODE));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQB],
+        ~(RISCV_IOMMU_CQB_LOG2SZ | RISCV_IOMMU_CQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQB],
+        ~(RISCV_IOMMU_FQB_LOG2SZ | RISCV_IOMMU_FQB_PPN));
+    stq_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQB],
+        ~(RISCV_IOMMU_PQB_LOG2SZ | RISCV_IOMMU_PQB_PPN));
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQMF |
+        RISCV_IOMMU_CQCSR_CMD_TO | RISCV_IOMMU_CQCSR_CMD_ILL);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_CQCSR], RISCV_IOMMU_CQCSR_CQON |
+        RISCV_IOMMU_CQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQMF |
+        RISCV_IOMMU_FQCSR_FQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_FQCSR], RISCV_IOMMU_FQCSR_FQON |
+        RISCV_IOMMU_FQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQMF |
+        RISCV_IOMMU_PQCSR_PQOF);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_PQCSR], RISCV_IOMMU_PQCSR_PQON |
+        RISCV_IOMMU_PQCSR_BUSY);
+    stl_le_p(&s->regs_wc[RISCV_IOMMU_REG_IPSR], ~0);
+    stl_le_p(&s->regs_ro[RISCV_IOMMU_REG_ICVEC], 0);
+    stq_le_p(&s->regs_rw[RISCV_IOMMU_REG_DDTP], s->ddtp);
+
+    /* Memory region for downstream access, if specified. */
+    if (s->target_mr) {
+        s->target_as = g_new0(AddressSpace, 1);
+        address_space_init(s->target_as, s->target_mr,
+            "riscv-iommu-downstream");
+    } else {
+        /* Fallback to global system memory. */
+        s->target_as = &address_space_memory;
+    }
+
+    /* Memory region for untranslated MRIF/MSI writes */
+    memory_region_init_io(&s->trap_mr, OBJECT(dev), &riscv_iommu_trap_ops, s,
+            "riscv-iommu-trap", ~0ULL);
+    address_space_init(&s->trap_as, &s->trap_mr, "riscv-iommu-trap-as");
+
+    /* Device translation context cache */
+    s->ctx_cache = g_hash_table_new_full(__ctx_hash, __ctx_equal,
+                                         g_free, NULL);
+    qemu_mutex_init(&s->ctx_lock);
+
+    s->iommus.le_next = NULL;
+    s->iommus.le_prev = NULL;
+    QLIST_INIT(&s->spaces);
+    qemu_mutex_init(&s->core_lock);
+    qemu_spin_init(&s->regs_lock);
+}
+
+static void riscv_iommu_unrealize(DeviceState *dev)
+{
+    RISCVIOMMUState *s = RISCV_IOMMU(dev);
+
+    qemu_mutex_destroy(&s->core_lock);
+    g_hash_table_unref(s->ctx_cache);
+}
+
+static Property riscv_iommu_properties[] = {
+    DEFINE_PROP_UINT32("version", RISCVIOMMUState, version,
+        RISCV_IOMMU_SPEC_DOT_VER),
+    DEFINE_PROP_UINT32("bus", RISCVIOMMUState, bus, 0x0),
+    DEFINE_PROP_BOOL("intremap", RISCVIOMMUState, enable_msi, TRUE),
+    DEFINE_PROP_BOOL("off", RISCVIOMMUState, enable_off, TRUE),
+    DEFINE_PROP_BOOL("s-stage", RISCVIOMMUState, enable_s_stage, TRUE),
+    DEFINE_PROP_BOOL("g-stage", RISCVIOMMUState, enable_g_stage, TRUE),
+    DEFINE_PROP_LINK("downstream-mr", RISCVIOMMUState, target_mr,
+        TYPE_MEMORY_REGION, MemoryRegion *),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void riscv_iommu_class_init(ObjectClass *klass, void* data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    /* internal device for riscv-iommu-{pci/sys}, not user-creatable */
+    dc->user_creatable = false;
+    dc->realize = riscv_iommu_realize;
+    dc->unrealize = riscv_iommu_unrealize;
+    device_class_set_props(dc, riscv_iommu_properties);
+}
+
+static const TypeInfo riscv_iommu_info = {
+    .name = TYPE_RISCV_IOMMU,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(RISCVIOMMUState),
+    .class_init = riscv_iommu_class_init,
+};
+
+static const char *IOMMU_FLAG_STR[] = {
+    "NA",
+    "RO",
+    "WR",
+    "RW",
+};
+
+/* RISC-V IOMMU Memory Region - Address Translation Space */
+static IOMMUTLBEntry riscv_iommu_memory_region_translate(
+    IOMMUMemoryRegion *iommu_mr, hwaddr addr,
+    IOMMUAccessFlags flag, int iommu_idx)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    RISCVIOMMUContext *ctx;
+    void *ref;
+    IOMMUTLBEntry iotlb = {
+        .iova = addr,
+        .target_as = as->iommu->target_as,
+        .addr_mask = ~0ULL,
+        .perm = flag,
+    };
+
+    ctx = riscv_iommu_ctx(as->iommu, as->devid, iommu_idx, &ref);
+    if (ctx == NULL) {
+        /* Translation disabled or invalid. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    } else if (riscv_iommu_translate(as->iommu, ctx, &iotlb)) {
+        /* Translation disabled or fault reported. */
+        iotlb.addr_mask = 0;
+        iotlb.perm = IOMMU_NONE;
+    }
+
+    /* Trace all dma translations with original access flags. */
+    trace_riscv_iommu_dma(as->iommu->parent_obj.id, PCI_BUS_NUM(as->devid),
+                          PCI_SLOT(as->devid), PCI_FUNC(as->devid), iommu_idx,
+                          IOMMU_FLAG_STR[flag & IOMMU_RW], iotlb.iova,
+                          iotlb.translated_addr);
+
+    riscv_iommu_ctx_put(as->iommu, ref);
+
+    return iotlb;
+}
+
+static int riscv_iommu_memory_region_notify(
+    IOMMUMemoryRegion *iommu_mr, IOMMUNotifierFlag old,
+    IOMMUNotifierFlag new, Error **errp)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+
+    if (old == IOMMU_NOTIFIER_NONE) {
+        as->notifier = true;
+        trace_riscv_iommu_notifier_add(iommu_mr->parent_obj.name);
+    } else if (new == IOMMU_NOTIFIER_NONE) {
+        as->notifier = false;
+        trace_riscv_iommu_notifier_del(iommu_mr->parent_obj.name);
+    }
+
+    return 0;
+}
+
+static inline bool pci_is_iommu(PCIDevice *pdev)
+{
+    return pci_get_word(pdev->config + PCI_CLASS_DEVICE) == 0x0806;
+}
+
+static AddressSpace *riscv_iommu_find_as(PCIBus *bus, void *opaque, int devfn)
+{
+    RISCVIOMMUState *s = (RISCVIOMMUState *) opaque;
+    PCIDevice *pdev = pci_find_device(bus, pci_bus_num(bus), devfn);
+    AddressSpace *as = NULL;
+
+    if (pdev && pci_is_iommu(pdev)) {
+        return s->target_as;
+    }
+
+    /* Find first registered IOMMU device */
+    while (s->iommus.le_prev) {
+        s = *(s->iommus.le_prev);
+    }
+
+    /* Find first matching IOMMU */
+    while (s != NULL && as == NULL) {
+        as = riscv_iommu_space(s, PCI_BUILD_BDF(pci_bus_num(bus), devfn));
+        s = s->iommus.le_next;
+    }
+
+    return as ? as : &address_space_memory;
+}
+
+static const PCIIOMMUOps riscv_iommu_ops = {
+    .get_address_space = riscv_iommu_find_as,
+};
+
+void riscv_iommu_pci_setup_iommu(RISCVIOMMUState *iommu, PCIBus *bus,
+        Error **errp)
+{
+    if (bus->iommu_ops &&
+        bus->iommu_ops->get_address_space == riscv_iommu_find_as) {
+        /* Allow multiple IOMMUs on the same PCIe bus, link known devices */
+        RISCVIOMMUState *last = (RISCVIOMMUState *)bus->iommu_opaque;
+        QLIST_INSERT_AFTER(last, iommu, iommus);
+    } else if (!bus->iommu_ops && !bus->iommu_opaque) {
+        pci_setup_iommu(bus, &riscv_iommu_ops, iommu);
+    } else {
+        error_setg(errp, "can't register secondary IOMMU for PCI bus #%d",
+            pci_bus_num(bus));
+    }
+}
+
+static int riscv_iommu_memory_region_index(IOMMUMemoryRegion *iommu_mr,
+    MemTxAttrs attrs)
+{
+    return attrs.unspecified ? RISCV_IOMMU_NOPROCID : (int)attrs.pid;
+}
+
+static int riscv_iommu_memory_region_index_len(IOMMUMemoryRegion *iommu_mr)
+{
+    RISCVIOMMUSpace *as = container_of(iommu_mr, RISCVIOMMUSpace, iova_mr);
+    return 1 << as->iommu->pid_bits;
+}
+
+static void riscv_iommu_memory_region_init(ObjectClass *klass, void *data)
+{
+    IOMMUMemoryRegionClass *imrc = IOMMU_MEMORY_REGION_CLASS(klass);
+
+    imrc->translate = riscv_iommu_memory_region_translate;
+    imrc->notify_flag_changed = riscv_iommu_memory_region_notify;
+    imrc->attrs_to_index = riscv_iommu_memory_region_index;
+    imrc->num_indexes = riscv_iommu_memory_region_index_len;
+}
+
+static const TypeInfo riscv_iommu_memory_region_info = {
+    .parent = TYPE_IOMMU_MEMORY_REGION,
+    .name = TYPE_RISCV_IOMMU_MEMORY_REGION,
+    .class_init = riscv_iommu_memory_region_init,
+};
+
+static void riscv_iommu_register_mr_types(void)
+{
+    type_register_static(&riscv_iommu_memory_region_info);
+    type_register_static(&riscv_iommu_info);
+}
+
+type_init(riscv_iommu_register_mr_types);
diff --git a/hw/riscv/Kconfig b/hw/riscv/Kconfig
index a2030e3a6f..f69d6e3c8e 100644
--- a/hw/riscv/Kconfig
+++ b/hw/riscv/Kconfig
@@ -1,3 +1,6 @@
+config RISCV_IOMMU
+    bool
+
 config RISCV_NUMA
     bool
 
@@ -47,6 +50,7 @@ config RISCV_VIRT
     select SERIAL
     select RISCV_ACLINT
     select RISCV_APLIC
+    select RISCV_IOMMU
     select RISCV_IMSIC
     select SIFIVE_PLIC
     select SIFIVE_TEST
diff --git a/hw/riscv/meson.build b/hw/riscv/meson.build
index f872674093..cbc99c6e8e 100644
--- a/hw/riscv/meson.build
+++ b/hw/riscv/meson.build
@@ -10,5 +10,6 @@ riscv_ss.add(when: 'CONFIG_SIFIVE_U', if_true: files('sifive_u.c'))
 riscv_ss.add(when: 'CONFIG_SPIKE', if_true: files('spike.c'))
 riscv_ss.add(when: 'CONFIG_MICROCHIP_PFSOC', if_true: files('microchip_pfsoc.c'))
 riscv_ss.add(when: 'CONFIG_ACPI', if_true: files('virt-acpi-build.c'))
+riscv_ss.add(when: 'CONFIG_RISCV_IOMMU', if_true: files('riscv-iommu.c'))
 
 hw_arch += {'riscv': riscv_ss}
diff --git a/hw/riscv/trace-events b/hw/riscv/trace-events
new file mode 100644
index 0000000000..3d5c33102d
--- /dev/null
+++ b/hw/riscv/trace-events
@@ -0,0 +1,14 @@
+# See documentation at docs/devel/tracing.rst
+
+# riscv-iommu.c
+riscv_iommu_new(const char *id, unsigned b, unsigned d, unsigned f) "%s: device attached %04x:%02x.%d"
+riscv_iommu_flt(const char *id, unsigned b, unsigned d, unsigned f, uint64_t reason, uint64_t iova) "%s: fault %04x:%02x.%u reason: 0x%"PRIx64" iova: 0x%"PRIx64
+riscv_iommu_pri(const char *id, unsigned b, unsigned d, unsigned f, uint64_t iova) "%s: page request %04x:%02x.%u iova: 0x%"PRIx64
+riscv_iommu_dma(const char *id, unsigned b, unsigned d, unsigned f, unsigned pasid, const char *dir, uint64_t iova, uint64_t phys) "%s: translate %04x:%02x.%u #%u %s 0x%"PRIx64" -> 0x%"PRIx64
+riscv_iommu_msi(const char *id, unsigned b, unsigned d, unsigned f, uint64_t iova, uint64_t phys) "%s: translate %04x:%02x.%u MSI 0x%"PRIx64" -> 0x%"PRIx64
+riscv_iommu_mrif_notification(const char *id, uint32_t nid, uint64_t phys) "%s: sent MRIF notification 0x%x to 0x%"PRIx64
+riscv_iommu_cmd(const char *id, uint64_t l, uint64_t u) "%s: command 0x%"PRIx64" 0x%"PRIx64
+riscv_iommu_notifier_add(const char *id) "%s: dev-iotlb notifier added"
+riscv_iommu_notifier_del(const char *id) "%s: dev-iotlb notifier removed"
+riscv_iommu_notify_int_vector(uint32_t cause, uint32_t vector) "Interrupt cause 0x%x sent via vector 0x%x"
+riscv_iommu_icvec_write(uint32_t orig, uint32_t actual) "ICVEC write: incoming 0x%x actual 0x%x"
