[PATCH 1/3] KVM: arm64: Fix comment in fpsimd_lazy_switch_to_host()

[Fuad Tabba]

Hi Mark,

On Tue, 6 Jan 2026 at 17:37, Mark Rutland <mark.rutland at arm.com> wrote:
>
> The comment in fpsimd_lazy_switch_to_host() erroneously says guest traps
> for FPSIMD/SVE/SME are disabled by fpsimd_lazy_switch_to_guest(). In
> reality, the traps are disabled by __activate_cptr_traps(), and
> fpsimd_lazy_switch_to_guest() only manipulates the SVE vector length.
>
> This was mistake; I accidentally copy+pasted the wrong function name in
> commit:
>
>   59419f10045b ("KVM: arm64: Eagerly switch ZCR_EL{1,2}")
>
> Fix the comment.
>
> Fixes: 59419f10045b ("KVM: arm64: Eagerly switch ZCR_EL{1,2}")
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Fuad Tabba <tabba at google.com>
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Mark Brown <broonie at kernel.org>
> Cc: Oliver Upton <oliver.upton at linux.dev>
> Cc: Will Deacon <will at kernel.org>
> ---
>  arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index c5d5e5b86eaf0..8dce3da85da35 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -495,7 +495,7 @@ static inline void fpsimd_lazy_switch_to_host(struct kvm_vcpu *vcpu)
>         /*
>          * When the guest owns the FP regs, we know that guest+hyp traps for
>          * any FPSIMD/SVE/SME features exposed to the guest have been disabled
> -        * by either fpsimd_lazy_switch_to_guest() or kvm_hyp_handle_fpsimd()
> +        * by either __activate_cptr_traps() or kvm_hyp_handle_fpsimd()
>          * prior to __guest_entry(). As __guest_entry() guarantees a context

nit: Since the new function name is shorter, you could reflow the
paragraph and move the word 'prior' to the line above.

Either way:
Tested-by: Fuad Tabba <tabba at google.com>
Reviewed-by: Fuad Tabba <tabba at google.com>

 Cheers,
/fuad



>          * synchronization event, we don't need an ISB here to avoid taking
>          * traps for anything that was exposed to the guest.
> --
> 2.30.2
>