On Sun, Jun 04, 2017 at 02:43:54PM +0200, Andrew Jones wrote: > 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.
Whoops, i forgot to say that I reviewed this: Reviewed-by: Christoffer Dall <[email protected]> > > Signed-off-by: Andrew Jones <[email protected]> > --- > 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; > } > -- > 2.9.4 > _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
