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SubjectRe: [PATCH 21/24] KVM: x86: always update CR3 in VMCB
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On 20/05/20 20:22, Sean Christopherson wrote:
> As an alternative fix, what about marking VCPU_EXREG_CR3 dirty in
> __set_sregs()? E.g.
>
> /*
> * Loading vmcs02.GUEST_CR3 is handled by nested VM-Enter, but
> * it can be explicitly dirtied by KVM_SET_SREGS.
> */
> if (is_guest_mode(vcpu) &&
> !test_bit(VCPU_EXREG_CR3, (ulong *)&vcpu->arch.regs_dirty))
>
> There's already a dependency on __set_sregs() doing
> kvm_register_mark_available() before kvm_mmu_reset_context(), i.e. the
> code is already a bit kludgy. The dirty check would make the kludge less
> subtle and provide explicit documentation.

A comment in __set_sregs is certainly a good idea. But checking for
dirty seems worse since the caching of CR3 is a bit special in this
respect (it's never marked dirty).

This patch should probably be split too, so that the Fixes tags are
separate for Intel and AMD.

Paolo

>> guest_cr3 = vcpu->arch.cr3;
>
> The comment that's just below the context is now stale, e.g. replace
> vmcs01.GUEST_CR3 with vmcs.GUEST_CR3.
>
>> --
>> 2.18.2
>>
>>
>

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