[lkml]   [2019]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2] kvm/svm: PKU not currently supported
On 19/12/19 21:32, Sean Christopherson wrote:
> On Thu, Dec 19, 2019 at 02:17:59PM -0600, John Allen wrote:
>> 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 <>
>> ---
>> v2:
>> -Introduce kvm_x86_ops->pku_supported()
> I like the v1 approach better, it's less code to unwind when SVM gains
> support for virtualizaing PKU.
> The existing cases of kvm_x86_ops->*_supported() in __do_cpuid_func() are
> necessary to handle cases where it may not be possible to expose a feature
> even though it's supported in hardware, host and KVM, e.g. VMX's separate
> MSR-based features and PT's software control to hide it from guest. In
> this case, hiding PKU is purely due to lack of support in KVM. The SVM
> series to enable PKU can then delete a single line of SVM code instead of
> having to go back in and do surgery on x86 and VMX.

I sort of liked the V1 approach better, in that I liked using
set_supported_cpuid but I didn't like *removing* features from it.

I think all *_supported() should be removed, and the code moved from
__do_cpuid_func() to set_supported_cpuid.

For now, however, this one is consistent with other features so I am
applying it.


 \ /
  Last update: 2019-12-20 10:26    [W:0.049 / U:2.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site