Re: [Patch v2 3/4] x86/speculation: Extend per process STIBP to AMD cpus.

From: Ingo Molnar
Date: Tue Oct 02 2018 - 05:27:39 EST



* Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote:

> From: Thomas Lendacky <Thomas.Lendacky@xxxxxxx>
>
> We extend the app to app spectre v2 mitigation using STIBP
> to the AMD cpus. We need to take care of special

s/to the AMD cpus
/to AMD CPUs

> cases for AMD cpu's update of SPEC_CTRL MSR to avoid double
> writing of MSRs from update to SSBD and STIBP.

s/AMD cpu
/AMD CPU

>
> Originally-by: Thomas Lendacky <Thomas.Lendacky@xxxxxxx>
> Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kernel/process.c | 48 +++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 38 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index cb24014..4a3a672 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -399,6 +399,10 @@ static __always_inline void set_spec_ctrl_state(unsigned long tifn)
> {
> u64 msr = x86_spec_ctrl_base;
>
> + /*
> + * AMD cpu may have used a different method to update SSBD, so
> + * we need to be sure we are using the SPEC_CTRL MSR for SSBD.

s/AMD cpu may have used a different method to update SSBD
/AMD CPUs may use a different method to update the SSBD

Thanks,

Ingo