lkml.org 
[lkml]   [2019]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] kvm/svm: PKU not currently supported
On Thu, Dec 19, 2019 at 08:09:57PM +0100, Vitaly Kuznetsov wrote:
> John Allen <john.allen@amd.com> writes:
>
> > Current SVM implementation does not have support for handling PKU. Guests
> > running on a host with future AMD cpus that support the feature will read
> > garbage from the PKRU register and will hit segmentation faults on boot as
> > memory is getting marked as protected that should not be. Ensure that cpuid
> > from SVM does not advertise the feature.
> >
> > Signed-off-by: John Allen <john.allen@amd.com>
> > ---
> > arch/x86/kvm/svm.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > index 122d4ce3b1ab..f911aa1b41c8 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -5933,6 +5933,8 @@ static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
> > if (avic)
> > entry->ecx &= ~bit(X86_FEATURE_X2APIC);
> > break;
> > + case 0x7:
> > + entry->ecx &= ~bit(X86_FEATURE_PKU);
>
> Would it make more sense to introduce kvm_x86_ops->pku_supported() (and
> return false for SVM and boot_cpu_has(X86_FEATURE_PKU) for vmx) so we
> don't set the bit in the first place?

Yes, I think you're right. I had initially planned to do it that way so I
already have a patch ready. I'll send it up pronto.

>
> > case 0x80000001:
> > if (nested)
> > entry->ecx |= (1 << 2); /* Set SVM bit */
>
> --
> Vitaly
>

\
 
 \ /
  Last update: 2019-12-19 20:50    [W:0.062 / U:13.836 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site