Re: [PATCH v2] x86/bugs: Add "unknown" reporting for MMIO Stale Data

Pawan Gupta
2022-08-18T18:20:53Z

On Thu, Aug 18, 2022 at 12:08:24PM +0200, Borislav Petkov wrote:
> On Wed, Aug 03, 2022 at 02:41:32PM -0700, Pawan Gupta wrote:
> > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> > index 6761668100b9..fe3f7e762b80 100644
> > --- a/arch/x86/kernel/cpu/bugs.c
> > +++ b/arch/x86/kernel/cpu/bugs.c
> > @@ -433,7 +433,8 @@ static void __init mmio_select_mitigation(void)
> > u64 ia32_cap;
> >
> > if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) ||
> > - cpu_mitigations_off()) {
> > + boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN) ||
> > + cpu_mitigations_off()) {
> > mmio_mitigation = MMIO_MITIGATION_OFF;
> > return;
> > }
>
> Needs also:
>
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index d08c5589fa59..da7c361f47e0 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -539,6 +539,8 @@ static void __init md_clear_update_mitigation(void)
> pr_info("TAA: %s\n", taa_strings[taa_mitigation]);
> if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA))
> pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]);
> + else if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN))
> + pr_info("MMIO Stale Data: Unknown: No mitigations\n");
> }
>
> static void __init md_clear_select_mitigation(void)
>
> I've added it.

Thanks