From 4841e0dd4f53c127b11947bdbe4423b5e9014ebc Mon Sep 17 00:00:00 2001 From: James Hogan Date: Mon, 28 Nov 2016 22:45:04 +0000 Subject: [PATCH] KVM: MIPS: Update vcpu->mode and vcpu->cpu MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Paolo Bonzini Cc: "Radim Krčmář" Cc: Ralf Baechle Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org --- arch/mips/kvm/mips.c | 18 ++++++++++++++++++ arch/mips/kvm/mmu.c | 2 ++ 2 files changed, 20 insertions(+) diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c index 9b72e2c55a0c..ff5e34293227 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 @@ skip_emul: 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); -- 2.20.1