Re: [RFC PATCH v2 21/34] x86/msr: Utilize the alternatives mechanism to write MSR

H. Peter Anvin
2025-04-25T15:29:49Z

On April 25, 2025 5:33:17 AM PDT, Peter Zijlstra <peterz@infradead.org> wrote:
>On Wed, Apr 23, 2025 at 06:05:19PM +0200, Jürgen Groß wrote:
>
>> > It's not a major change, but when it is patched to use the immediate
>> > form MSR write instruction, it's straightforwardly streamlined.
>>
>> It should be rather easy to switch the current wrmsr/rdmsr paravirt patching
>> locations to use the rdmsr/wrmsr instructions instead of doing a call to
>> native_*msr().
>
>Right, just make the Xen functions asm stubs that expect the instruction
>registers instead of C-abi and ALT_NOT_XEN the thing.
>
>Shouldn't be hard at all.

And that's what we will be doing. We already have code for that.