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@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: "Radim Krčmář" <rkrcmar@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
arch/mips/kvm/mips.c | 18 ++++++++++++++++++
arch/mips/kvm/mmu.c | 2 ++
2 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 90c28fbf4829..325e98367b30 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);
@@ -1331,6 +1339,8 @@ 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();
@@ -1486,6 +1496,14 @@ 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);
/*
diff --git a/arch/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 09f5da706d9a..e41ee36dd626 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -696,6 +696,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
local_irq_save(flags);
+ vcpu->cpu = cpu;
if (vcpu->arch.last_sched_cpu != cpu) {
kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
@@ -723,6 +724,7 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
cpu = smp_processor_id();
vcpu->arch.last_sched_cpu = cpu;
+ vcpu->cpu = -1;
/* save guest state in registers */
kvm_mips_callbacks->vcpu_put(vcpu, cpu);
--
git-series 0.8.10
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