KVM: MIPS: Update vcpu->mode and vcpu->cpu
Keep the vcpu->mode and vcpu->cpu variables up to date so that
kvm_make_all_cpus_request() has a chance of functioning correctly. This
will soon need to be used for kvm_flush_remote_tlbs().
We can easily update vcpu->cpu when the VCPU context is loaded or saved,
which will happen when accessing guest context and when the guest is
scheduled in and out.
We need to be a little careful with vcpu->mode though, as we will in
future be checking for outstanding VCPU requests, and this must be done
after the value of IN_GUEST_MODE in vcpu->mode is visible to other CPUs.
Otherwise the other CPU could fail to trigger an IPI to wait for
completion dispite the VCPU request not being seen.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 9b72e2c..ff5e342 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -365,6 +365,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
guest_enter_irqoff();
trace_kvm_enter(vcpu);
+ /*
+ * Make sure the read of VCPU requests in vcpu_run() callback is not
+ * reordered ahead of the write to vcpu->mode, or we could miss a TLB
+ * flush request while the requester sees the VCPU as outside of guest
+ * mode and not needing an IPI.
+ */
+ smp_store_mb(vcpu->mode, IN_GUEST_MODE);
+
r = kvm_mips_callbacks->vcpu_run(run, vcpu);
trace_kvm_out(vcpu);
@@ -1326,6 +1334,8 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
u32 inst;
int ret = RESUME_GUEST;
+ vcpu->mode = OUTSIDE_GUEST_MODE;
+
/* re-enable HTW before enabling interrupts */
htw_start();
@@ -1481,6 +1491,14 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
if (ret == RESUME_GUEST) {
trace_kvm_reenter(vcpu);
+ /*
+ * Make sure the read of VCPU requests in vcpu_reenter()
+ * callback is not reordered ahead of the write to vcpu->mode,
+ * or we could miss a TLB flush request while the requester sees
+ * the VCPU as outside of guest mode and not needing an IPI.
+ */
+ smp_store_mb(vcpu->mode, IN_GUEST_MODE);
+
kvm_mips_callbacks->vcpu_reenter(run, vcpu);
/*