Re: [PATCH] KVM: arm64: Pend host SErrors for protected vCPUs through HCR_EL2.VSE

[Oliver Upton <oupton@kernel.org>]

Hi Fuad,

On Mon, Oct 05, 2026 at 06:03:52AM +0100, Fuad Tabba wrote:
> diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
> index d6c4fc16f8795..49a342b078365 100644
> --- a/arch/arm64/kvm/inject_fault.c
> +++ b/arch/arm64/kvm/inject_fault.c
> @@ -378,8 +378,11 @@ int kvm_inject_serror_esr(struct kvm_vcpu *vcpu, u64 esr)
>  	 *
>  	 * As we're emulating the SError injection we need to explicitly populate
>  	 * ESR_ELx.EC because hardware will not do it on our behalf.
> +	 *
> +	 * A protected vCPU's PSTATE and SCTLR2_EL1 live at EL2, so pend through
> +	 * HCR_EL2.VSE and let the guest's own masking apply.
>  	 */
> -	if (!serror_is_masked(vcpu)) {
> +	if (!vcpu_is_protected(vcpu) && !serror_is_masked(vcpu)) {
>  		pend_serror_exception(vcpu);
>  		esr |= FIELD_PREP(ESR_ELx_EC_MASK, ESR_ELx_EC_SERROR) | ESR_ELx_IL;
>  		vcpu_write_sys_reg(vcpu, esr, exception_esr_elx(vcpu));

The emulated injection is only necessary when vcpu_has_nv(), it was just
convenient for the sake of testing that everything short circuits to
emulation instead of VSE.

I see Marc suggests letting the stale PSTATE.A value force the desired
behavior which seems fine to me. If that doesn't work, I'd rather
emulated injection be predicated on vcpu_has_nv() than
vcpu_is_protected() with the appropriate rephrasing of the preceding
comment.

Thanks,
Oliver