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

[Juergen Gross <jgross@suse.com>]

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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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