On 11/8/23 18:12, Nina Schoetterl-Glausch wrote:
> STFLE can be interpretively executed.
> This occurs when the facility list designation is unequal to zero.
> Perform the check before applying the address mask instead of after.
>
> Fixes: 66b630d5b7f2 ("KVM: s390: vsie: support STFLE interpretation")
> Reviewed-by: Claudio Imbrenda <[email protected]>
> Acked-by: David Hildenbrand <[email protected]>
> Signed-off-by: Nina Schoetterl-Glausch <[email protected]>
> ---
> arch/s390/kvm/vsie.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
> index 61499293c2ac..d989772fe211 100644
> --- a/arch/s390/kvm/vsie.c
> +++ b/arch/s390/kvm/vsie.c
> @@ -988,9 +988,10 @@ static void retry_vsie_icpt(struct vsie_page *vsie_page)
> static int handle_stfle(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
> {
> struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
> - __u32 fac = READ_ONCE(vsie_page->scb_o->fac) & 0x7ffffff8U;
> + __u32 fac = READ_ONCE(vsie_page->scb_o->fac);
>
> if (fac && test_kvm_facility(vcpu->kvm, 7)) {
> + fac = fac & 0x7ffffff8U;
Switch the retry and the facility assignment.
Add the following comment:
Facility list origin (FLO) is in bits 1 - 28 of the FLD so we need to
mask here before reading.
Apart from that this looks fine to me.
> retry_vsie_icpt(vsie_page);
> if (read_guest_real(vcpu, fac, &vsie_page->fac,
> sizeof(vsie_page->fac)))