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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
This commit is contained in:
James Hogan 2016-11-28 22:45:04 +00:00
parent 06c158c96e
commit 4841e0dd4f
2 changed files with 20 additions and 0 deletions
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18
arch/mips/kvm/mips.c
View File

@ -365,6 +365,14 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
guest_enter_irqoff(); guest_enter_irqoff();
trace_kvm_enter(vcpu); 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); r = kvm_mips_callbacks->vcpu_run(run, vcpu);
trace_kvm_out(vcpu); trace_kvm_out(vcpu);
@ -1326,6 +1334,8 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
u32 inst; u32 inst;
int ret = RESUME_GUEST; int ret = RESUME_GUEST;
vcpu->mode = OUTSIDE_GUEST_MODE;
/* re-enable HTW before enabling interrupts */ /* re-enable HTW before enabling interrupts */
htw_start(); htw_start();
@ -1481,6 +1491,14 @@ skip_emul:
if (ret == RESUME_GUEST) { if (ret == RESUME_GUEST) {
trace_kvm_reenter(vcpu); 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); kvm_mips_callbacks->vcpu_reenter(run, vcpu);
/* /*

2
arch/mips/kvm/mmu.c
View File

@ -696,6 +696,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
local_irq_save(flags); local_irq_save(flags);
vcpu->cpu = cpu;
if (vcpu->arch.last_sched_cpu != cpu) { if (vcpu->arch.last_sched_cpu != cpu) {
kvm_debug("[%d->%d]KVM VCPU[%d] switch\n", kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id); 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(); cpu = smp_processor_id();
vcpu->arch.last_sched_cpu = cpu; vcpu->arch.last_sched_cpu = cpu;
vcpu->cpu = -1;
/* save guest state in registers */ /* save guest state in registers */
kvm_mips_callbacks->vcpu_put(vcpu, cpu); kvm_mips_callbacks->vcpu_put(vcpu, cpu);