Re: [Xen-devel] [PATCH 3/3] x86: avoid FS/GS base reads when possible

2017-10-20 Thread Andrew Cooper
On 20/10/17 15:24, Jan Beulich wrote: > They're being zeroed a few lines down when non-null selectors are being > found in the respective registers. > > Signed-off-by: Jan Beulich Given that this is within an cpu_has_fsgsbase conditional, there is a moderate chance that the conditional is more ov

[Xen-devel] [PATCH 3/3] x86: avoid FS/GS base reads when possible

2017-10-20 Thread Jan Beulich
They're being zeroed a few lines down when non-null selectors are being found in the respective registers. Signed-off-by: Jan Beulich --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1449,10 +1449,11 @@ static void save_segments(struct vcpu *v if ( cpu_has_fsgsbase && !is_pv_32