On Wed, May 30, 2018 at 9:33 AM Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
>
> On Tue, May 22, 2018 at 09:54:20AM -0700, Jim Mattson wrote:
> > Previously, we only called indirect_branch_prediction_barrier on the
> > logical CPU that freed a vmcb. This function should be called on all
> > logical CPUs that last loaded the vmcb in question.
> >
> > Fixes: 15d45071523d ("KVM/x86: Add IBPB support")
> > Reported-by: Neel Natu <neelnatu@xxxxxxxxxx>
> > Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> Thank you!
> > ---
> > arch/x86/kvm/svm.c | 20 +++++++++++++++-----
> > 1 file changed, 15 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > index 220e5a89465a..ffa27f75e323 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -2172,21 +2172,31 @@ static struct kvm_vcpu *svm_create_vcpu(struct kvm *kvm, unsigned int id)
> > return ERR_PTR(err);
> > }
> >
> > +static void svm_clear_current_vmcb(struct vmcb *vmcb)
> > +{
> > + int i;
> > +
> > + for_each_online_cpu(i)
> > + cmpxchg(&per_cpu(svm_data, i)->current_vmcb, vmcb, NULL);
> > +}
> > +
> > static void svm_free_vcpu(struct kvm_vcpu *vcpu)
> > {
> > struct vcpu_svm *svm = to_svm(vcpu);
> >
> > + /*
> > + * The vmcb page can be recycled, causing a false negative in
> > + * svm_vcpu_load(). So, ensure that no logical CPU has this
> > + * vmcb page recorded as its current vmcb.
> > + */
> > + svm_clear_current_vmcb(svm->vmcb);
> > +
> > __free_page(pfn_to_page(__sme_clr(svm->vmcb_pa) >> PAGE_SHIFT));
> > __free_pages(virt_to_page(svm->msrpm), MSRPM_ALLOC_ORDER);
> > __free_page(virt_to_page(svm->nested.hsave));
> > __free_pages(virt_to_page(svm->nested.msrpm), MSRPM_ALLOC_ORDER);
> > kvm_vcpu_uninit(vcpu);
> > kmem_cache_free(kvm_vcpu_cache, svm);
> > - /*
> > - * The vmcb page can be recycled, causing a false negative in
> > - * svm_vcpu_load(). So do a full IBPB now.
> > - */
> > - indirect_branch_prediction_barrier();
> > }
> >
> > static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
> > --
> > 2.17.0.441.gb46fe60e1d-goog
> >
Ping.
