diff options
| author | Sheng Yang <sheng@linux.intel.com> | 2009-04-27 20:35:43 +0800 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-06-10 11:48:50 +0300 |
| commit | 522c68c4416de3cd3e11a9ff10d58e776a69ae1e (patch) | |
| tree | 62940e35988f5e2a52df10276882ec64518ee369 /arch/x86/kvm/vmx.c | |
| parent | 4b12f0de33a64dfc624b2480f55b674f7fa23ef2 (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.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 59b080c262e8..e8a5649f9c15 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; } |