Messages in this thread | | | Subject | Re: [PATCH] KVM: x86/mmu: Calculate and check "full" mmu_role for nested MMU | From | Paolo Bonzini <> | Date | Fri, 11 Jun 2021 18:49:25 +0200 |
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On 11/06/21 18:45, Sean Christopherson wrote: >> Along which path though? I would have naively expected those to be driven >> only by the context->root_level. > The functional code is driven by context->root_level, but if KVM doesn't include > the level in the mmu_role then it will fail to update context->root_level when > L2 changes from 32-bit PAE to 64-bit. If all the CR0/CR4/EFER bits remain the > same, only the level will differ. Without this patch, role.level is always '0' > for the nested MMU. >
Yes the problem is the
if (new_role.as_u64 == g_context->mmu_role.as_u64) return;
and the patch lets you preserve the optimization instead of dropping it. I was wondering if I was missing something else because of the "when walking the guest page tables" remark.
Paolo
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