Re: [PATCH v3 07/10] KVM: s390: Return -EINTR if a signal was pending while faulting-in

[Janosch Frank <frankja@linux.ibm.com>]

On 7/27/26 17:02, Claudio Imbrenda wrote:
> If a signal is pending while trying to fault-in a page, return -EINTR
> instead of -EAGAIN.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Fixes: e907ae530133 ("KVM: s390: Add helper functions for fault handling")
> ---
>   arch/s390/kvm/faultin.c   |  4 ++--
>   arch/s390/kvm/intercept.c | 18 ++++++++----------
>   arch/s390/kvm/pv.c        |  2 +-
>   3 files changed, 11 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/s390/kvm/faultin.c b/arch/s390/kvm/faultin.c
> index fee80047bd94..4ff4c5970956 100644
> --- a/arch/s390/kvm/faultin.c
> +++ b/arch/s390/kvm/faultin.c
> @@ -92,8 +92,8 @@ int kvm_s390_faultin_gfn(struct kvm_vcpu *vcpu, struct kvm *kvm, struct guest_fa
>   		if (is_noslot_pfn(f->pfn))
>   			return PGM_ADDRESSING;
>   		/* Signal pending: try again. */
> -		if (f->pfn == KVM_PFN_ERR_SIGPENDING)
> -			return -EAGAIN;
> +		if (is_sigpending_pfn(f->pfn))
> +			return -EINTR;
>   		/* Check if it's read-only memory; don't try to actually handle that case. */
>   		if (f->pfn == KVM_PFN_ERR_RO_FAULT)
>   			return -EOPNOTSUPP;

The code above is what I'd expect from the description but there's more 
code in this patch. Are we fixing multiple things?


> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
> index 1980df61ef30..08f2128db147 100644
> --- a/arch/s390/kvm/intercept.c
> +++ b/arch/s390/kvm/intercept.c
> @@ -369,27 +369,25 @@ static int handle_mvpg_pei(struct kvm_vcpu *vcpu)
>   	if (rc)
>   		return kvm_s390_inject_prog_cond(vcpu, rc);
>   
> -	do {
> -		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(srcaddr), false);
> -	} while (rc == -EAGAIN);
> -	if (rc)
> -		return rc;
> -
> -	/* Ensure that the source is paged-in, no actual access -> no key checking */
> +	/* Ensure that the destination is paged-in, no actual access -> no key checking */
>   	rc = guest_translate_address_with_key(vcpu, vcpu->run->s.regs.gprs[reg1],
>   					      reg1, &dstaddr, GACC_STORE, 0);
>   	if (rc)
>   		return kvm_s390_inject_prog_cond(vcpu, rc);
>   
> +	kvm_s390_retry_instr(vcpu);
> +
>   	do {
> -		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(dstaddr), true);
> +		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(srcaddr), false);
>   	} while (rc == -EAGAIN);
>   	if (rc)
>   		return rc;
>   
> -	kvm_s390_retry_instr(vcpu);
> +	do {
> +		rc = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(dstaddr), true);
> +	} while (rc == -EAGAIN);
>   
> -	return 0;
> +	return rc;
>   }
>   
>   static int handle_partial_execution(struct kvm_vcpu *vcpu)
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 1beacc841ca8..dc204b521052 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -809,7 +809,7 @@ static int unpack_one(struct kvm *kvm, unsigned long addr, u64 tweak,
>   			return -EAGAIN;
>   	}
>   
> -	if (ret && ret != -EAGAIN)
> +	if (ret && ret != -EAGAIN && ret != -EINTR)
>   		KVM_UV_EVENT(kvm, 3, "PROTVIRT VM UNPACK: failed addr %llx with rc %x rrc %x",
>   			     uvcb.gaddr, *rc, *rrc);
>   	return ret;