Re: [PATCH v5 00/16] x86: make PAT and MTRR independent from each other

[Juergen Gross]

On 02.11.22 19:04, Borislav Petkov wrote:
> On Wed, Nov 02, 2022 at 08:46:57AM +0100, Juergen Gross wrote:
> > Today PAT can't be used without MTRR being available, unless MTRR is at
> > least configured via CONFIG_MTRR and the system is running as Xen PV
> > guest. In this case PAT is automatically available via the hypervisor,
> > but the PAT MSR can't be modified by the kernel and MTRR is disabled.
> >
> > The same applies to a kernel built with no MTRR support: it won't
> > allow to use the PAT MSR, even if there is no technical reason for
> > that, other than setting up PAT on all CPUs the same way (which is a
> > requirement of the processor's cache management) is relying on some
> > MTRR specific code.
> >
> > Fix all of that by:
>
> One of the AMD test boxes here says with this:
>
> ...
> [    0.863466] PCI: not using MMCONFIG
> [    0.863475] PCI: Using configuration type 1 for base access
> [    0.863478] PCI: Using configuration type 1 for extended access
> [    0.866733] mtrr: your CPUs had inconsistent MTRRdefType settings
> [    0.866737] mtrr: probably your BIOS does not setup all CPUs.
> [    0.866740] mtrr: corrected configuration.
> [    0.869350] kprobes: kprobe jump-optimization is enabled. All kprobes are optimized if possible.
> ...
>
> Previous logs don't have it:
>
> PCI: not using MMCONFIG
> PCI: Using configuration type 1 for base access
> PCI: Using configuration type 1 for extended access
> kprobes: kprobe jump-optimization is enabled. All kprobes are optimized if possible.

Weird. I can't spot any modification which could have caused that.

Would it be possible to identify the patch causing that?


Juergen

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