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Date: Wed, 20 May 2020 22:14:47 +0200 From: Paolo Bonzini <pbonzini@...hat.com> To: Sean Christopherson <sean.j.christopherson@...el.com> Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org, vkuznets@...hat.com, Joerg Roedel <jroedel@...e.de> Subject: Re: [PATCH 21/24] KVM: x86: always update CR3 in VMCB 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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