On April 25, 2025 5:51:27 AM PDT, "Jürgen Groß" <jgross@xxxxxxxx> wrote: >On 25.04.25 14:33, Peter Zijlstra 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. > >Correct. And for the new immediate form we can use ALTERNATIVE_3(). > > >Juergen Yes; in the ultimate case there are *four* alternatives, but the concept is the same and again we have it implemented already.
