From 6a6d73be12fbe492d0678cd84d3b35e2bc9698e4 Mon Sep 17 00:00:00 2001 From: Andrew Jones Date: Sun, 4 Jun 2017 14:43:54 +0200 Subject: [PATCH] KVM: arm/arm64: properly use vcpu requests arm/arm64 already has one VCPU request used when setting pause, but it doesn't properly check requests in VCPU RUN. Check it and also make sure we set vcpu->mode at the appropriate time (before the check) and with the appropriate barriers. See Documentation/virtual/kvm/vcpu-requests.rst. Also make sure we don't leave any vcpu requests we don't intend to handle later set in the request bitmap. If we don't clear them, then kvm_request_pending() may return true when it shouldn't. Using VCPU requests properly fixes a small race where pause could get set just as a VCPU was entering guest mode. Signed-off-by: Andrew Jones Reviewed-by: Christoffer Dall Signed-off-by: Christoffer Dall --- arch/arm/kvm/handle_exit.c | 1 + arch/arm64/kvm/handle_exit.c | 1 + virt/kvm/arm/arm.c | 14 ++++++++++++-- virt/kvm/arm/psci.c | 1 + 4 files changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c index 5fd7968cdae9..a2b4f7b82356 100644 --- a/arch/arm/kvm/handle_exit.c +++ b/arch/arm/kvm/handle_exit.c @@ -72,6 +72,7 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) trace_kvm_wfx(*vcpu_pc(vcpu), false); vcpu->stat.wfi_exit_stat++; kvm_vcpu_block(vcpu); + kvm_clear_request(KVM_REQ_UNHALT, vcpu); } kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index fa1b18e364fc..17d8a1677a0b 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -89,6 +89,7 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run) trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false); vcpu->stat.wfi_exit_stat++; kvm_vcpu_block(vcpu); + kvm_clear_request(KVM_REQ_UNHALT, vcpu); } kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu)); diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index 3c387fdc4a9e..138212605ad9 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -546,6 +546,7 @@ void kvm_arm_resume_guest(struct kvm *kvm) kvm_for_each_vcpu(i, vcpu, kvm) { vcpu->arch.pause = false; + kvm_clear_request(KVM_REQ_VCPU_EXIT, vcpu); swake_up(kvm_arch_vcpu_wq(vcpu)); } } @@ -638,8 +639,18 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) run->exit_reason = KVM_EXIT_INTR; } + /* + * Ensure we set mode to IN_GUEST_MODE after we disable + * interrupts and before the final VCPU requests check. + * See the comment in kvm_vcpu_exiting_guest_mode() and + * Documentation/virtual/kvm/vcpu-requests.rst + */ + smp_store_mb(vcpu->mode, IN_GUEST_MODE); + if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) || - vcpu->arch.power_off || vcpu->arch.pause) { + kvm_request_pending(vcpu) || + vcpu->arch.power_off || vcpu->arch.pause) { + vcpu->mode = OUTSIDE_GUEST_MODE; local_irq_enable(); kvm_pmu_sync_hwstate(vcpu); kvm_timer_sync_hwstate(vcpu); @@ -655,7 +666,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) */ trace_kvm_entry(*vcpu_pc(vcpu)); guest_enter_irqoff(); - vcpu->mode = IN_GUEST_MODE; ret = kvm_call_hyp(__kvm_vcpu_run, vcpu); diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c index a08d7a93aebb..f68be2cc6256 100644 --- a/virt/kvm/arm/psci.c +++ b/virt/kvm/arm/psci.c @@ -57,6 +57,7 @@ static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) * for KVM will preserve the register state. */ kvm_vcpu_block(vcpu); + kvm_clear_request(KVM_REQ_UNHALT, vcpu); return PSCI_RET_SUCCESS; }