Messages in this thread | | | Subject | Re: [PATCH] KVM: MMU: Fix guest stuck during boot due to read/write emulation against GVA | From | David Hildenbrand <> | Date | Fri, 11 Aug 2017 08:40:55 +0200 |
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On 11.08.2017 08:13, Paolo Bonzini wrote: > On 11/08/2017 07:59, Wanpeng Li wrote: >> From: Wanpeng Li <wanpeng.li@hotmail.com> >> >> Commit c016004494b0 (KVM: x86: Avoid guest page table walk when gpa_available >> is set) avoids the page table walk when cr2 has already contained a valid GPA. >> However, that is not the truth if ept == 0 and shadow page table is used. In >> this scenario cr2 can just contains a valid GVA. The commit results in guest >> stuck during boot due to read/write emulation against GVA instead of GPA of >> the guest. >> >> This patch fixes it by not setting the gpa_available flag if the shadow page table >> is used. > > Yup, I got these on my overnight tests too. A better fix that I was > going to commit today is: > > if (vcpu->arch.mmu.direct_map) { > vcpu->arch.gpa_available = true; > vcpu->arch.gpa_val = fault_address; > } >
Makes sense to me. Can we add a comment?
/* with shadow page tables, cr2 could contain a GVA, not a GPA */
> because AMD gets here even if npt=1. > > Paolo
--
Thanks,
David
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