[120/121] KVM: s390: move kvm_guest_enter,exit closer to sie

[Ben Hutchings]

3.2.51-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dominik Dingel <dingel@xxxxxxxxxxxxxxxxxx>

commit 2b29a9fdcb92bfc6b6f4c412d71505869de61a56 upstream.

Any uaccess between guest_enter and guest_exit could trigger a page fault,
the page fault handler would handle it as a guest fault and translate a
user address as guest address.

Signed-off-by: Dominik Dingel <dingel@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[bwh: Backported to 3.2: adjust context and add the rc variable]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/s390/kvm/kvm-s390.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -469,6 +469,8 @@ int kvm_arch_vcpu_ioctl_set_mpstate(stru
 
 static void __vcpu_run(struct kvm_vcpu *vcpu)
 {
+	int rc;
+
 	memcpy(&vcpu->arch.sie_block->gg14, &vcpu->arch.guest_gprs[14], 16);
 
 	if (need_resched())
@@ -479,21 +481,24 @@ static void __vcpu_run(struct kvm_vcpu *
 
 	kvm_s390_deliver_pending_interrupts(vcpu);
 
+	VCPU_EVENT(vcpu, 6, "entering sie flags %x",
+		   atomic_read(&vcpu->arch.sie_block->cpuflags));
+
 	vcpu->arch.sie_block->icptcode = 0;
 	local_irq_disable();
 	kvm_guest_enter();
 	local_irq_enable();
-	VCPU_EVENT(vcpu, 6, "entering sie flags %x",
-		   atomic_read(&vcpu->arch.sie_block->cpuflags));
-	if (sie64a(vcpu->arch.sie_block, vcpu->arch.guest_gprs)) {
+	rc = sie64a(vcpu->arch.sie_block, vcpu->arch.guest_gprs);
+	local_irq_disable();
+	kvm_guest_exit();
+	local_irq_enable();
+
+	if (rc) {
 		VCPU_EVENT(vcpu, 3, "%s", "fault in sie instruction");
 		kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
 	}
 	VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
 		   vcpu->arch.sie_block->icptcode);
-	local_irq_disable();
-	kvm_guest_exit();
-	local_irq_enable();
 
 	memcpy(&vcpu->arch.guest_gprs[14], &vcpu->arch.sie_block->gg14, 16);
 }

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