[v6,03/10] IOMMU: add common API for device reserved memory

Commit Message

Marek Marczykowski-Górecki Sept. 2, 2022, 1:17 p.m. UTC

Add API similar to rmrr= and ivmd= arguments, but in a common code. This
will allow drivers to register reserved memory regardless of the IOMMU
vendor.
The direct reason for this API is xhci-dbc console driver (aka xue),
that needs to use DMA. But future change may unify command line
arguments for user-supplied reserved memory, and it may be useful for
other drivers in the future too.

This commit just introduces an API, subsequent patches will plug it in
appropriate places. The reserved memory ranges needs to be saved
locally, because at the point when they are collected, Xen doesn't know
yet which IOMMU driver will be used.

Signed-off-by: Marek Marczykowski-Górecki <[e-mail]>
Acked-by: Jan Beulich <[e-mail]>
---
Changes in v5:
- fix indentation, keep full "reserved_device_memory" for consistency
  with iommu_get_reserved_device_memory
Changes in v4:
- mark functions as __init
- use pci_sbdf_t type
Changes in v3:
 - adjust code style
---
 xen/drivers/passthrough/iommu.c | 46 ++++++++++++++++++++++++++++++++++-
 xen/include/xen/iommu.h         | 14 ++++++++++-
 2 files changed, 60 insertions(+)

Patch

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 134cdb47e0dc..5e2a720d29b9 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -669,6 +669,52 @@  bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
     return is_iommu_enabled(d) && test_bit(feature, dom_iommu(d)->features);
 }
 
+#define MAX_EXTRA_RESERVED_RANGES 20
+struct extra_reserved_range {
+    unsigned long start;
+    unsigned long nr;
+    pci_sbdf_t sbdf;
+};
+static unsigned int __initdata nr_extra_reserved_ranges;
+static struct extra_reserved_range __initdata
+    extra_reserved_ranges[MAX_EXTRA_RESERVED_RANGES];
+
+int __init iommu_add_extra_reserved_device_memory(unsigned long start,
+                                                  unsigned long nr,
+                                                  pci_sbdf_t sbdf)
+{
+    unsigned int idx;
+
+    if ( nr_extra_reserved_ranges >= MAX_EXTRA_RESERVED_RANGES )
+        return -ENOMEM;
+
+    idx = nr_extra_reserved_ranges++;
+    extra_reserved_ranges[idx].start = start;
+    extra_reserved_ranges[idx].nr = nr;
+    extra_reserved_ranges[idx].sbdf = sbdf;
+
+    return 0;
+}
+
+int __init iommu_get_extra_reserved_device_memory(iommu_grdm_t *func,
+                                                  void *ctxt)
+{
+    unsigned int idx;
+    int ret;
+
+    for ( idx = 0; idx < nr_extra_reserved_ranges; idx++ )
+    {
+        ret = func(extra_reserved_ranges[idx].start,
+                   extra_reserved_ranges[idx].nr,
+                   extra_reserved_ranges[idx].sbdf.sbdf,
+                   ctxt);
+        if ( ret < 0 )
+            return ret;
+    }
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 1240d7762d99..4f22fc1bed55 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -304,6 +304,20 @@  struct iommu_ops {
 #endif
 };
 
+/*
+ * To be called by Xen internally, to register extra RMRR/IVMD ranges.
+ * Needs to be called before IOMMU initialization.
+ */
+extern int iommu_add_extra_reserved_device_memory(unsigned long start,
+                                                  unsigned long nr,
+                                                  pci_sbdf_t sbdf);
+/*
+ * To be called by specific IOMMU driver during initialization,
+ * to fetch ranges registered with iommu_add_extra_reserved_device_memory().
+ */
+extern int iommu_get_extra_reserved_device_memory(iommu_grdm_t *func,
+                                                  void *ctxt);
+
 #include <asm/iommu.h>
 
 #ifndef iommu_call