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

On Sat, Jul 30, 2022 at 12:02:34AM +0200, Borislav Petkov wrote:

On Fri, Jul 29, 2022 at 02:46:27PM -0700, Pawan Gupta wrote:

...

Let me see if there is a way to distinguish between 4. and 5. below:

CPU category X86_BUG_MMIO_STALE_DATA X86_BUG_MMIO_UNKNOWN

1. Known affected (in cpu list) 1 0
2. CPUs with HW immunity (MMIO_NO=1) 0 0
3. Other vendors 0 0
4. Older Intel CPUs 0 1
5. Not affected current CPUs (but MMIO_NO=0) 0 ?

Not affected current CPUs should be arch_cap_mmio_immune() == true, no?

That would be true in most cases, with some exceptions like systems that did not update the microcode.