Re: [Xen-devel] [PATCH] x86/VT-x: Disable MSR intercept for SHADOW_GS_BASE.

[Tim Deegan <tim@xxxxxxx>]

At 14:02 +0000 on 14 Nov (1384434176), Andrew Cooper wrote:
> Intercepting this MSR is pointless - The swapgs instruction does not cause a
> vmexit, so the cached result of this is potentially stale after the next guest
> instruction.  It is correctly saved and restored on vcpu context switch.
> 
> Furthermore, 64bit Windows writes to this MSR on every thread context switch,
> so interception causes a substantial performance hit.
> 
> From: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Tim Deegan <tim@xxxxxxx>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel