KVM: s390: vsie: simulate VCPU SIE entry/exit

VCPU requests and VCPU blocking right now don't take care of the vSIE
(as it was not necessary until now). But we want to have synchronous VCPU
requests that will also be handled before running the vSIE again.

So let's simulate a SIE entry of the VCPU when calling the sie during
vSIE handling and check for PROG_ flags. The existing infrastructure
(e.g. exit_sie()) will then detect that the SIE (in form of the vSIE) is
running and properly kick the vSIE CPU, resulting in it leaving the vSIE
loop and therefore the vSIE interception handler, allowing it to handle
VCPU requests.

E.g. if we want to modify the crycb of the VCPU and make sure that any
masks also get applied to the VSIE crycb shadow (which uses masks from the
VCPU crycb), we will need a way to hinder the vSIE from running and make
sure to process the updated crycb before reentering the vSIE again.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20180925231641.4954-2-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index a2b28cd1e3fe..12b970701c26 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -830,7 +830,7 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
 	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
 	int guest_bp_isolation;
-	int rc;
+	int rc = 0;
 
 	handle_last_fault(vcpu, vsie_page);
 
@@ -858,7 +858,18 @@ static int do_vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	guest_enter_irqoff();
 	local_irq_enable();
 
-	rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
+	/*
+	 * Simulate a SIE entry of the VCPU (see sie64a), so VCPU blocking
+	 * and VCPU requests also hinder the vSIE from running and lead
+	 * to an immediate exit. kvm_s390_vsie_kick() has to be used to
+	 * also kick the vSIE.
+	 */
+	vcpu->arch.sie_block->prog0c |= PROG_IN_SIE;
+	barrier();
+	if (!kvm_s390_vcpu_sie_inhibited(vcpu))
+		rc = sie64a(scb_s, vcpu->run->s.regs.gprs);
+	barrier();
+	vcpu->arch.sie_block->prog0c &= ~PROG_IN_SIE;
 
 	local_irq_disable();
 	guest_exit_irqoff();
@@ -1005,7 +1016,8 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		if (rc == -EAGAIN)
 			rc = 0;
 		if (rc || scb_s->icptcode || signal_pending(current) ||
-		    kvm_s390_vcpu_has_irq(vcpu, 0))
+		    kvm_s390_vcpu_has_irq(vcpu, 0) ||
+		    kvm_s390_vcpu_sie_inhibited(vcpu))
 			break;
 	}
 
@@ -1122,7 +1134,8 @@ int kvm_s390_handle_vsie(struct kvm_vcpu *vcpu)
 	if (unlikely(scb_addr & 0x1ffUL))
 		return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
 
-	if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0))
+	if (signal_pending(current) || kvm_s390_vcpu_has_irq(vcpu, 0) ||
+	    kvm_s390_vcpu_sie_inhibited(vcpu))
 		return 0;
 
 	vsie_page = get_vsie_page(vcpu->kvm, scb_addr);