| Message ID | 20231108171229.3404476-2-nsg@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: s390: Fix minor bugs in STFLE shadowing | expand |
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 <imbrenda@linux.ibm.com> > Acked-by: David Hildenbrand <david@redhat.com> > Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com> > --- > 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)))
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; retry_vsie_icpt(vsie_page); if (read_guest_real(vcpu, fac, &vsie_page->fac, sizeof(vsie_page->fac)))
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 <imbrenda@linux.ibm.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com> --- arch/s390/kvm/vsie.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)