On Wed, 22 Nov 2023 12:58:11 +1000, Nicholas Piggin wrote:
> Before running a guest, the host process (e.g., QEMU) FP/VEC registers
> are saved if they were being used, similarly to when the kernel uses FP
> registers. The guest values are then be loaded into regs, and the host
> process registers will be restored lazily when it uses FP/VEC.
>
> KVM HV has a bug here: the host process registers do get saved, but the
> user MSR bits remain enabled, which indicates the registers are valid
> for the process. After they are clobbered by running the guest, this
> valid indication causes the host process to take on the FP/VEC regiter
> values of the guest.
>
> [...]
Applied to powerpc/fixes.
[1/1] KVM: PPC: Book3S HV: Fix KVM_RUN clobbering FP/VEC user registers
https://git.kernel.org/powerpc/c/dc158d23b33df9033bcc8e7117e8591dd2f9d125
cheers
