KVM: PPC: Book3s: PR: Disable preemption in vcpu_run

When entering the guest, we want to make sure we're not getting preempted
away, so let's disable preemption on entry, but enable it again while handling
guest exits.

Reported-by: Jörg Sommer <joerg@alea.gnuu.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 203a7b7b58b98ef4f6dfacc52a5747e4264f2893..19af2bf2b87d3c00df1a5f978a788cbefa590299 100644 (file)
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -517,6 +517,7 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
        run->ready_for_interrupt_injection = 1;
 
        trace_kvm_book3s_exit(exit_nr, vcpu);
+       preempt_enable();
        kvm_resched(vcpu);
        switch (exit_nr) {
        case BOOK3S_INTERRUPT_INST_STORAGE:
@@ -761,6 +762,8 @@ program_interrupt:
                        run->exit_reason = KVM_EXIT_INTR;
                        r = -EINTR;
                } else {
+                       preempt_disable();
+
                        /* In case an interrupt came in that was triggered
                         * from userspace (like DEC), we need to check what
                         * to inject now! */
@@ -923,10 +926,13 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 #endif
        ulong ext_msr;
 
+       preempt_disable();
+
        /* Check if we can run the vcpu at all */
        if (!vcpu->arch.sane) {
                kvm_run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-               return -EINVAL;
+               ret = -EINVAL;
+               goto out;
        }
 
        kvmppc_core_prepare_to_enter(vcpu);
@@ -934,7 +940,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
        /* No need to go into the guest when all we do is going out */
        if (signal_pending(current)) {
                kvm_run->exit_reason = KVM_EXIT_INTR;
-               return -EINTR;
+               ret = -EINTR;
+               goto out;
        }
 
        /* Save FPU state in stack */
@@ -1004,6 +1011,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
        current->thread.used_vsr = used_vsr;
 #endif
 
+out:
+       preempt_enable();
        return ret;
 }