linux-kernel - [PATCH 1/4] KVM: s390: vsie: Fix STFLE interpretive execution identification

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Date:   Fri,  3 Nov 2023 18:30:05 +0100
From:   Nina Schoetterl-Glausch <nsg@...ux.ibm.com>
To:     Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        David Hildenbrand <dahi@...ux.vnet.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>
Cc:     Nina Schoetterl-Glausch <nsg@...ux.ibm.com>, kvm@...r.kernel.org,
        Michael Mueller <mimu@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org,
        Cornelia Huck <cornelia.huck@...ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] KVM: s390: vsie: Fix STFLE interpretive execution identification

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")
Signed-off-by: Nina Schoetterl-Glausch <nsg@...ux.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;
 		retry_vsie_icpt(vsie_page);
 		if (read_guest_real(vcpu, fac, &vsie_page->fac,
 				    sizeof(vsie_page->fac)))
-- 
2.39.2