Re: [PATCH] target/i386: Export RFDS bit to guests

[Zhao Liu <zhao1.liu@intel.com>]

Hi Pawan,

On Wed, Mar 13, 2024 at 07:53:23AM -0700, Pawan Gupta wrote:
> Date: Wed, 13 Mar 2024 07:53:23 -0700
> From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Subject: [PATCH] target/i386: Export RFDS bit to guests
> 
> Register File Data Sampling (RFDS) is a CPU side-channel vulnerability
> that may expose stale register value. CPUs that set RFDS_NO bit in MSR
> IA32_ARCH_CAPABILITIES indicate that they are not vulnerable to RFDS.
> Similarly, RFDS_CLEAR indicates that CPU is affected by RFDS, and has
> the microcode to help mitigate RFDS.
> 
> Make RFDS_CLEAR and RFDS_NO bits available to guests.

Are these two bits going to be supported by microcode updates to
existing products?

(Let me aslo attach the related spec to make it easy for more people to
learn about backgrounds: 
https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/register-file-data-sampling.html)

> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> ---
>  target/i386/cpu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

LGTM,

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>