Re: [Xen-devel] [PATCH][RFC] FPU LWP 3/5: define new FPU interface functions: fpu_save, fpu_restore, fpu_reload

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 14.04.11 at 22:38, Wei Huang <wei.huang2@xxxxxxx> wrote:
> Current Xen implementation only support lazy FPU reload via CR0.TS. But 
> new FPU state isn't always tracked by CR0.TS bit. One example is AMD's 
> lightweight profiling. With this patch, Xen calls fpu_save() on vcpu 
> which is being scheduled out and fpu_restore() on vcpu which is being 
> scheduled in. The nonlazy FPU state is saved and restored in these two 
> functions.

This doesn't match the actual patch - only fpu_restore() is being
added to the context switch path, fpu_save() was there already,
saving both lazy and non-lazy state.

> This patch also defines fpu_reload() to handle lazy FPU state when #NM 
> is triggered.
> 
> Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
>...
>+/* Restore VCPU's FPU state when the vcpu is scheduled out */
>+void fpu_restore(struct vcpu *v)

The comment ought so say "in" rather than "out".

Jan


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