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authorPaolo Bonzini <pbonzini@redhat.com>2015-10-01 13:12:47 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2015-10-01 13:30:42 +0200
commit606decd67049217684e3cb5a54104d51ddd4ef35 (patch)
treecac2e61715bd29bdb93ab713b2764329d0d9b94a /arch
parent9bac175d8ed0b1dd3d3611c0713666b724eeace3 (diff)
downloadlinux-606decd67049217684e3cb5a54104d51ddd4ef35.tar.gz
Revert "KVM: x86: apply guest MTRR virtualization on host reserved pages"
This reverts commit fd717f11015f673487ffc826e59b2bad69d20fe5. It was reported to cause Machine Check Exceptions (bug 104091). Reported-by: harn-solo@gmx.de Cc: stable@vger.kernel.org # 4.2+ Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/svm.c7
-rw-r--r--arch/x86/kvm/vmx.c11
2 files changed, 13 insertions, 5 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 94b7d15db3fc..9e88078f4146 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1167,11 +1167,14 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
u8 mtrr;
/*
- * 1. MMIO: trust guest MTRR, so same as item 3.
+ * 1. MMIO: always map as UC
* 2. No passthrough: always map as WB, and force guest PAT to WB as well
* 3. Passthrough: can't guarantee the result, try to trust guest.
*/
- if (!is_mmio && !kvm_arch_has_assigned_device(vcpu->kvm))
+ if (is_mmio)
+ return _PAGE_NOCACHE;
+
+ if (!kvm_arch_has_assigned_device(vcpu->kvm))
return 0;
if (!kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED) &&
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 64076740251e..06ef4908ba61 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8617,17 +8617,22 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
u64 ipat = 0;
/* For VT-d and EPT combination
- * 1. MMIO: guest may want to apply WC, trust it.
+ * 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. So the same as item 1.
+ * 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 IPAT=1 to keep
* consistent with host MTRR
*/
- if (!is_mmio && !kvm_arch_has_noncoherent_dma(vcpu->kvm)) {
+ if (is_mmio) {
+ cache = MTRR_TYPE_UNCACHABLE;
+ goto exit;
+ }
+
+ if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) {
ipat = VMX_EPT_IPAT_BIT;
cache = MTRR_TYPE_WRBACK;
goto exit;