Re: [PATCH v2] KVM: s390: fix LPSWEY handling

[Sven Schnelle <svens@linux.ibm.com>]

Christian Borntraeger <borntraeger@linux.ibm.com> writes:

> in rare cases, e.g. for injecting a machine check we do intercept all
> load PSW instructions via ICTL_LPSW. With facility 193 a new variant
> LPSWEY was added. KVM needs to handle that as well.
>
> Fixes: a3efa8429266 ("KVM: s390: gen_facilities: allow facilities 165, 193, 194 and 196")
> Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |  1 +
>  arch/s390/kvm/kvm-s390.c         |  1 +
>  arch/s390/kvm/kvm-s390.h         | 15 +++++++++++++++
>  arch/s390/kvm/priv.c             | 32 ++++++++++++++++++++++++++++++++
>  4 files changed, 49 insertions(+)
>
> diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
> index 1be19cc9d73c..1a49b89706f8 100644
> --- a/arch/s390/kvm/priv.c
> +++ b/arch/s390/kvm/priv.c
> @@ -797,6 +797,36 @@ static int handle_lpswe(struct kvm_vcpu *vcpu)
>  	return 0;
>  }
>  
> +static int handle_lpswey(struct kvm_vcpu *vcpu)
> +{
> +	psw_t new_psw;
> +	u64 addr;
> +	int rc;
> +	u8 ar;
> +
> +	vcpu->stat.instruction_lpswey++;
> +
> +	if (!test_kvm_facility(vcpu->kvm, 193))
> +		return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
> +
> +	if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
> +		return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
> +
> +	addr = kvm_s390_get_base_disp_siy(vcpu, &ar);
> +	if (addr & 7)
> +		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
> +
> +	rc = read_guest(vcpu, addr, ar, &new_psw, sizeof(new_psw));
> +	if (rc)
> +		return kvm_s390_inject_prog_cond(vcpu, rc);
> +
> +	vcpu->arch.sie_block->gpsw = new_psw;
> +	if (!is_valid_psw(&vcpu->arch.sie_block->gpsw))
> +		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);

Shouldn't the gpsw get updated with new_psw after the check? POP says "The operation
is suppressed on all addressing and protection exceptions."

> +
> +	return 0;
> +}