Re: [Xen-devel] [Patch 2/4] Refining Xsave/Xrestore support

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>@@ -1367,6 +1384,8 @@ static void __context_switch(void)
>         memcpy(stack_regs,
>                &n->arch.guest_context.user_regs,
>                CTXT_SWITCH_STACK_BYTES);
>+        if ( cpu_has_xsave )
>+            set_xcr0(n->arch.xcr0);

How slow is a write to xcr0? I.e. is it worth checking whether
current xcr0 matches the to be written value?

Jan


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