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Re: [Qemu-devel] [PATCH] x86/cpu: Enable CLDEMOTE(Demote Cache Line) cpu
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH] x86/cpu: Enable CLDEMOTE(Demote Cache Line) cpu feature |
Date: |
Thu, 3 May 2018 00:04:57 -0300 |
User-agent: |
Mutt/1.9.2 (2017-12-15) |
On Fri, May 04, 2018 at 11:57:33AM +0800, Jingqi Liu wrote:
> The CLDEMOTE instruction hints to hardware that the cache line that
> contains the linear address should be moved("demoted") from
> the cache(s) closest to the processor core to a level more distant
> from the processor core. This may accelerate subsequent accesses
> to the line by other cores in the same coherence domain,
> especially if the line was written by the core that demotes the line.
>
> Intel Snow Ridge has added new cpu feature, CLDEMOTE.
> The new cpu feature needs to be exposed to guest VM.
>
> The bit definition:
> CPUID.(EAX=7,ECX=0):ECX[bit 25] CLDEMOTE
>
> The release document ref below link:
> https://software.intel.com/sites/default/files/managed/c5/15/\
> architecture-instruction-set-extensions-programming-reference.pdf
>
> Signed-off-by: Jingqi Liu <address@hidden>
Thanks. Do you have a pointer to the corresponding
GET_SUPPORTED_CPUID patch in KVM?
--
Eduardo