Re: [PATCH 3/3] kvm: s390: Fix lpsw/e spec exception ilc reporting

[Heiko Carstens <hca@linux.ibm.com>]

On Thu, Apr 23, 2026 at 12:36:04PM +0000, Janosch Frank wrote:
> On early PSW specification exception the ILC has to be 0 according to
> architecture.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> Fixes: 48a3e950f4cee ("KVM: s390: Add support for machine checks.")
> ---
>  arch/s390/kvm/priv.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index 56e63679f9d1..9fd7d3f1d1e8 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -713,6 +713,7 @@ int is_valid_psw(psw_t *psw)
>  int kvm_s390_handle_lpsw(struct kvm_vcpu *vcpu)
>  {
>  	psw_t *gpsw = &vcpu->arch.sie_block->gpsw;
> +	struct kvm_s390_pgm_info info = {};
>  	psw32_t new_psw;
>  	u64 addr, iaddr;
>  	int rc;
> @@ -738,14 +739,18 @@ int kvm_s390_handle_lpsw(struct kvm_vcpu *vcpu)
>  	gpsw->addr = new_psw.addr & ~PSW32_ADDR_AMODE;
>  	vcpu->arch.sie_block->gbea = iaddr;
>  
> -	if (!is_valid_psw(gpsw))
> -		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
> +	if (!is_valid_psw(gpsw)) {
> +		info.code = PGM_SPECIFICATION;
> +		info.flags = KVM_S390_PGM_FLAGS_ILC_VALID;
> +		return kvm_s390_inject_prog_irq(vcpu, &info);
> +	}

Hmm... looking at the architecture: an odd instruction address in the PSW
does not result in an early specification exception, but a "normal"
specification exception. is_valid_psw() however also checks for an odd
instruction address. So I guess this is still not entirely correct.

I'm also wondering if the above implementation is correct if PER is enabled
when the specification happens...

Btw.: you may want to have consistent short descriptions for your two
patches. That is consistently use upper or lower case for "LPSW/E".