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Revert "KVM: x86: apply guest MTRR virtualization on host reserved pages" 

This reverts commit fd717f1101.
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>
hifive-unleashed-5.1
Paolo Bonzini 2015-10-01 13:12:47 +02:00
parent 9bac175d8e
commit 606decd670
2 changed files with 13 additions and 5 deletions
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7
arch/x86/kvm/svm.c
View File

@ -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) &&

11
arch/x86/kvm/vmx.c
View File

@ -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;