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>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 94b7d15..9e88078 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1167,11 +1167,14 @@
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) &&