KVM: s390: move kvm_guest_enter,exit closer to sie

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@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
[bwh: Backported to 3.2: adjust context and add the rc variable]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4db9b1e6a602646745a4f49e22fd3de1e6589c58..dd072b1add06ec475b9eda0c0bc36186be7a4f93 100644 (file)
--- 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(struct kvm_vcpu *vcpu,
 
 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 *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);
 }