[Qemu-devel] [PATCH v4 1/3] IOMMU: add option to enable VTD_CAP_CM to vIOMMU capility exposoed to guest

["Aviv B.D" <bd.aviv@gmail.com>]

From: "Aviv Ben-David" <bd.aviv@gmail.com>

This capability asks the guest to invalidate cache before each map operation.
We can use this invalidation to trap map operations in the hypervisor.

This capability only enabled when cache-mode property of the device is true.

Signed-off-by: Aviv Ben-David <bd.aviv@gmail.com>
---
 hw/i386/intel_iommu.c          | 5 +++++
 hw/i386/intel_iommu_internal.h | 1 +
 include/hw/i386/intel_iommu.h  | 2 ++
 3 files changed, 8 insertions(+)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 2efd69b..6e5ad7b 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2012,6 +2012,7 @@ static const MemoryRegionOps vtd_mem_ops = {
 
 static Property vtd_properties[] = {
     DEFINE_PROP_UINT32("version", IntelIOMMUState, version, 0),
+    DEFINE_PROP_BOOL("cache-mode", IntelIOMMUState, cache_mode_enabled, FALSE),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -2385,6 +2386,10 @@ static void vtd_init(IntelIOMMUState *s)
         s->ecap |= VTD_ECAP_IR | VTD_ECAP_EIM | VTD_ECAP_MHMV;
     }
 
+    if (s->cache_mode_enabled){
+        s->cap |= VTD_CAP_CM;
+    }
+
     vtd_reset_context_cache(s);
     vtd_reset_iotlb(s);
 
diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
index 0829a50..35d9f3a 100644
--- a/hw/i386/intel_iommu_internal.h
+++ b/hw/i386/intel_iommu_internal.h
@@ -201,6 +201,7 @@
 #define VTD_CAP_MAMV                (VTD_MAMV << 48)
 #define VTD_CAP_PSI                 (1ULL << 39)
 #define VTD_CAP_SLLPS               ((1ULL << 34) | (1ULL << 35))
+#define VTD_CAP_CM                  (1ULL << 7)
 
 /* Supported Adjusted Guest Address Widths */
 #define VTD_CAP_SAGAW_SHIFT         8
diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index a42dbd7..7a94f16 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -258,6 +258,8 @@ struct IntelIOMMUState {
     uint8_t womask[DMAR_REG_SIZE];  /* WO (write only - read returns 0) */
     uint32_t version;
 
+    bool cache_mode_enabled;        /* RO - is cap CM enabled? */
+
     dma_addr_t root;                /* Current root table pointer */
     bool root_extended;             /* Type of root table (extended or not) */
     bool dmar_enabled;              /* Set if DMA remapping is enabled */
-- 
1.9.1