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[RFC,07/12] IOMMU: add common API for device reserved memory

Message ID 8ba3e1cbfc7ee1d0a5da54e47f33a14c526691d3.1654486751.git-series.marmarek@invisiblethingslab.com (mailing list archive)
State Superseded
Headers show
Series Add Xue - console over USB 3 Debug Capability | expand

Commit Message

Marek Marczykowski-Górecki June 6, 2022, 3:40 a.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 <marmarek@invisiblethingslab.com>
---
 xen/drivers/passthrough/iommu.c | 40 ++++++++++++++++++++++++++++++++++-
 xen/include/xen/iommu.h         | 11 +++++++++-
 2 files changed, 51 insertions(+)
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Patch

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index 9393d987c788..5c4162912359 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -654,6 +654,46 @@  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 {
+    xen_pfn_t start;
+    xen_ulong_t nr;
+    u32 sbdf;
+};
+static unsigned int __initdata nr_extra_reserved_ranges;
+static struct extra_reserved_range __initdata extra_reserved_ranges[MAX_EXTRA_RESERVED_RANGES];
+
+int iommu_add_extra_reserved_device_memory(xen_pfn_t start, xen_ulong_t nr, u32 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 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,
+                   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 e0f82712ed73..97424130247c 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -296,6 +296,17 @@  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(xen_pfn_t start, xen_ulong_t nr, u32 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