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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c1c7c68..698fb82 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -622,14 +622,25 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
                kvm_s390_deliver_pending_interrupts(vcpu);
 
        vcpu->arch.sie_block->icptcode = 0;
-       preempt_disable();
-       kvm_guest_enter();
-       preempt_enable();
        VCPU_EVENT(vcpu, 6, "entering sie flags %x",
                   atomic_read(&vcpu->arch.sie_block->cpuflags));
        trace_kvm_s390_sie_enter(vcpu,
                                 atomic_read(&vcpu->arch.sie_block->cpuflags));
+
+       /*
+        * As PF_VCPU will be used in fault handler, between guest_enter
+        * and guest_exit should be no uaccess.
+        */
+       preempt_disable();
+       kvm_guest_enter();
+       preempt_enable();
        rc = sie64a(vcpu->arch.sie_block, vcpu->run->s.regs.gprs);
+       kvm_guest_exit();
+
+       VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
+                  vcpu->arch.sie_block->icptcode);
+       trace_kvm_s390_sie_exit(vcpu, vcpu->arch.sie_block->icptcode);
+
        if (rc) {
                if (kvm_is_ucontrol(vcpu->kvm)) {
                        rc = SIE_INTERCEPT_UCONTROL;
@@ -639,10 +650,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
                        rc = kvm_s390_inject_program_int(vcpu, PGM_ADDRESSING);
                }
        }
-       VCPU_EVENT(vcpu, 6, "exit sie icptcode %d",
-                  vcpu->arch.sie_block->icptcode);
-       trace_kvm_s390_sie_exit(vcpu, vcpu->arch.sie_block->icptcode);
-       kvm_guest_exit();
 
        memcpy(&vcpu->run->s.regs.gprs[14], &vcpu->arch.sie_block->gg14, 16);
        return rc;