Re: [Qemu-devel] [PATCH v6 1/3] IOMMU: add option to enable VTD_CAP_CM to vIOMMU capility exposoed to guest

[Jason Wang]

On 2016年11月08日 19:04, Aviv B.D wrote:
From: "Aviv Ben-David" <bd.a...@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.

Hi:

Like I've asked twice in the past, I want to know why don't you cache 
translation faults as what spec required (especially this is a guest 
visible behavior)?

Btw, please cc me on posting future versions.

Thanks


Signed-off-by: Aviv Ben-David <bd.a...@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 1655a65..834887f 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -2017,6 +2017,7 @@ static Property vtd_properties[] = {
      DEFINE_PROP_ON_OFF_AUTO("eim", IntelIOMMUState, intr_eim,
                              ON_OFF_AUTO_AUTO),
      DEFINE_PROP_BOOL("x-buggy-eim", IntelIOMMUState, buggy_eim, false),
+    DEFINE_PROP_BOOL("cache-mode", IntelIOMMUState, cache_mode_enabled, FALSE),
      DEFINE_PROP_END_OF_LIST(),
  };
  
@@ -2391,6 +2392,10 @@ static void vtd_init(IntelIOMMUState *s)
          assert(s->intr_eim != ON_OFF_AUTO_AUTO);
      }
  
+    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 1989c1e..42d293f 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 */