Thanks Greg, Andy

How about c198b121b1a1d7a7171770c634cd49191bac4477? Will both patches go to stable kernel?

BR. Ning.

-----Original Message----- From: gregkh@linuxfoundation.org [mailto:gregkh@linuxfoundation.org] Sent: Tuesday, January 23, 2018 3:26 PM To: Andy Lutomirski luto@kernel.org Cc: Zhang, Ning A ning.a.zhang@intel.com; tglx@linutronix.de; stable@vger.kernel.org; linux-kernel@vger.kernel.org Subject: Re: backport Rewrite sync_core() to use IRET-to-self to stable kernels?

On Mon, Jan 22, 2018 at 07:06:29PM -0800, Andy Lutomirski wrote:

On Mon, Jan 22, 2018 at 6:59 PM, Zhang, Ning A ning.a.zhang@intel.com wrote:

...

hello, Greg, Andy, Thomas

would you like to backport these two patches to LTS kernel?

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable. git/commit/arch/x86/include/asm/processor.h?h=v4.14.14&id=1c52d859cb 2d417e7216d3e56bb7fea88444cec9

x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable. git/commit/arch/x86/include/asm/processor.h?h=v4.14.14&id=c198b121b1 a1d7a7171770c634cd49191bac4477

x86/asm: Rewrite sync_core() to use IRET-to-self

I'd be in favor of backporting 1c52d859cb2d417e7216d3e56bb7fea88444cec9. I see no compelling reason to backport the other one, since it doesn't fix a bug. Greg, can you do this?

I'll work on this after this round of stable kernels are released.

thanks,

greg k-h

When Linux runs as a guest OS, CPUID is privileged instruction, sync_core() will be very slow.

If apply this patch, 200ms will be saved for kernel initial, when Linux runs as a guest OS.

BR. Ning.

-----Original Message----- From: gregkh@linuxfoundation.org [mailto:gregkh@linuxfoundation.org] Sent: Wednesday, January 24, 2018 5:01 PM To: Zhang, Ning A ning.a.zhang@intel.com Cc: Andy Lutomirski luto@kernel.org; tglx@linutronix.de; stable@vger.kernel.org; linux-kernel@vger.kernel.org Subject: Re: backport Rewrite sync_core() to use IRET-to-self to stable kernels?

On Wed, Jan 24, 2018 at 08:19:44AM +0000, Zhang, Ning A wrote:

Thanks Greg, Andy

How about c198b121b1a1d7a7171770c634cd49191bac4477?

Why do you think that is needed in the older stable kernels? What problem does it solve? Do any distros have this patch in their kernels?

thanks,

greg k-h

On Tue, Jan 23, 2018 at 08:25:33AM +0100, gregkh@linuxfoundation.org wrote:

On Mon, Jan 22, 2018 at 07:06:29PM -0800, Andy Lutomirski wrote:

...

On Mon, Jan 22, 2018 at 6:59 PM, Zhang, Ning A ning.a.zhang@intel.com wrote:

...

hello, Greg, Andy, Thomas

would you like to backport these two patches to LTS kernel?

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/comm...

x86/asm/32: Make sync_core() handle missing CPUID on all 32-bit kernels

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/comm...

x86/asm: Rewrite sync_core() to use IRET-to-self

I'd be in favor of backporting 1c52d859cb2d417e7216d3e56bb7fea88444cec9. I see no compelling reason to backport the other one, since it doesn't fix a bug. Greg, can you do this?

I'll work on this after this round of stable kernels are released.

Now applied, thanks.

greg k-h