Re: [PATCH 1/10] KVM MMU: fix for calculating gpa in invlpg code

From: Avi Kivity
Date: Fri Apr 23 2010 - 07:24:08 EST


On 04/22/2010 09:12 AM, Xiao Guangrong wrote:
If the guest is 32-bit, we should use 'quadrant' to adjust gpa
offset


Good catch. Only affects kvm_mmu_pte_write(), so I don't think this had ill effects other than not prefetching the correct address?

@@ -478,9 +478,14 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
((level == PT_DIRECTORY_LEVEL&& is_large_pte(*sptep))) ||
((level == PT_PDPE_LEVEL&& is_large_pte(*sptep)))) {
struct kvm_mmu_page *sp = page_header(__pa(sptep));
+ int offset = 0;
+
+ if (PTTYPE == 32)
+ offset = sp->role.quadrant<< PT64_LEVEL_BITS;;

Wrong for PT_DIRECTORY_LEVEL (should be q << 8). Also, too many semicolons.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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