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authorSheng Yang <sheng@linux.intel.com>2009-04-27 20:35:43 +0800
committerAvi Kivity <avi@redhat.com>2009-06-10 11:48:50 +0300
commit522c68c4416de3cd3e11a9ff10d58e776a69ae1e (patch)
tree62940e35988f5e2a52df10276882ec64518ee369 /arch/x86/kvm/vmx.c
parent4b12f0de33a64dfc624b2480f55b674f7fa23ef2 (diff)
KVM: Enable snooping control for supported hardware
Memory aliases with different memory type is a problem for guest. For the guest without assigned device, the memory type of guest memory would always been the same as host(WB); but for the assigned device, some part of memory may be used as DMA and then set to uncacheable memory type(UC/WC), which would be a conflict of host memory type then be a potential issue. Snooping control can guarantee the cache correctness of memory go through the DMA engine of VT-d. [avi: fix build on ia64] Signed-off-by: Sheng Yang <sheng@linux.intel.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/vmx.c')
-rw-r--r--arch/x86/kvm/vmx.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 59b080c262e..e8a5649f9c1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3581,11 +3581,26 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
{
u64 ret;
+ /* For VT-d and EPT combination
+ * 1. MMIO: always map as UC
+ * 2. EPT with VT-d:
+ * a. VT-d without snooping control feature: can't guarantee the
+ * result, try to trust guest.
+ * b. VT-d with snooping control feature: snooping control feature of
+ * VT-d engine can guarantee the cache correctness. Just set it
+ * to WB to keep consistent with host. So the same as item 3.
+ * 3. EPT without VT-d: always map as WB and set IGMT=1 to keep
+ * consistent with host MTRR
+ */
if (is_mmio)
ret = MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT;
+ else if (vcpu->kvm->arch.iommu_domain &&
+ !(vcpu->kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY))
+ ret = kvm_get_guest_memory_type(vcpu, gfn) <<
+ VMX_EPT_MT_EPTE_SHIFT;
else
- ret = (kvm_get_guest_memory_type(vcpu, gfn) <<
- VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IGMT_BIT;
+ ret = (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT)
+ | VMX_EPT_IGMT_BIT;
return ret;
}