On Mon, Jun 08, 2020 at 11:12:35AM +0100, Liam Merwick wrote: > On 05/06/2020 21:07, Sean Christopherson wrote: > >Reinitialize IA32_FEAT_CTL on the BSP during wakeup to handle the case > >where firmware doesn't initialize or save/restore across S3. This fixes > >a bug where IA32_FEAT_CTL is left uninitialized and results in VMXON > >taking a #GP due to VMX not being fully enabled, i.e. breaks KVM. > > > >Use init_ia32_feat_ctl() to "restore" IA32_FEAT_CTL as it already deals > >with the case where the MSR is locked, and because APs already redo > >init_ia32_feat_ctl() during suspend by virtue of the SMP boot flow being > >used to reinitialize APs upon wakeup. Do the call in the early wakeup > >flow to avoid dependencies in the syscore_ops chain, e.g. simply adding > >a resume hook is not guaranteed to work, as KVM does VMXON in its own > >resume hook, kvm_resume(), when KVM has active guests. > > > >Reported-by: Brad Campbell <lists2009@xxxxxxxxxxxxxxx> > >Cc: Maxim Levitsky <mlevitsk@xxxxxxxxxx> > >Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > >Cc: kvm@xxxxxxxxxxxxxxx > > Should it have the following tag since it fixes a commit introduced in 5.6? > Cc: stable@xxxxxxxxxxxxxxx # v5.6 It definitely warrants a backport to v5.6. I didn't include a Cc to stable because I swear I had seen an email fly by that stated an explicit Cc is unnecessary/unwanted for tip-tree patches, but per a recent statement from Boris it looks like I'm simply confused[*]. I'll add the Cc in v2. [*] https://lkml.kernel.org/r/20200417164752.GF7322@xxxxxxx > >Fixes: 21bd3467a58e ("KVM: VMX: Drop initialization of IA32_FEAT_CTL MSR") > >Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
