On 2016/3/8 20:11, Paolo Bonzini wrote:
On 08/03/2016 13:09, Yang Zhang wrote:
if (!enable_unrestricted_guest && !is_paging(vcpu))
The comment says "Pkeys is disabled if CPU is in non-paging mode in
hardware". Why to check enable_unrestricted_guest here?
If !enable_unrestricted_guest, the CPU is always running with CR0.PG=1
and CR4 needs to be modified.
If enable_unrestricted_guest, the CPU automatically disables
SMEP/SMAP/PKU when the guest sets CR0.PG=0.
Thanks for you explanation. It would be better to add it into the below
comment to tell why only care !enable_unrestricted_guest case.
Paolo
/*
- * SMEP/SMAP is disabled if CPU is in non-paging mode in
+ * SMEP/SMAP/PKU is disabled if CPU is in non-paging mode in
* hardware. However KVM always uses paging mode without
* unrestricted guest.
- * To emulate this behavior, SMEP/SMAP needs to be manually
+ * To emulate this behavior, SMEP/SMAP/PKU needs to be manually
* disabled when guest switches to non-paging mode.
*/
- hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP);
+ hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE);
--
best regards
yang
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