On Wed, May 20, 2020 at 10:14:47PM +0200, Paolo Bonzini wrote: > 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). That's why I thought it was so clever :-) > This patch should probably be split too, so that the Fixes tags are > separate for Intel and AMD. That would be nice.
