On 03/07/2016 04:32 AM, Paolo Bonzini wrote:
On 06/03/2016 10:28, Xiao Guangrong wrote:
This patch disables CPUID:PKU without ept, because pkeys is not yet
implemented for shadow paging.
Does the PKRU is loaded/saved during vm-enter/vm-exit?
Yes, through XSAVE/XRSTOR (which uses eager mode when PKE is active).
You mean eager fpu? however, eager-fpu depends on 'eagerfpu' which is a kernel
parameter and this patchset did not force it on.
However, even if we use eager-fpu kvm still can lazily save/load due to some
fpu optimizations in kvm.
BTW, I just very quickly go through the spec, it seems VMX lacks the
ability to intercept the access to PKRU. Right?
Indeed RDPKRU/WRPKRU cannot be intercepted.
Er, i was thinking using this feature to speedup write-protection for
shadow page table and dirty-logging... it seems not easy as PKRU can not
be intercepted. :(
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