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

Borislav Petkov
2022-08-18T10:08:41Z

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.

--
Regards/Gruss,
Boris.