Add a suspend request and move the WFI execution into check_vcpu_requests(), next to the power-off logic. This will allow userspace implementing PSCI to request WFI before returning to the guest.
Signed-off-by: Jean-Philippe Brucker jean-philippe@linaro.org
--- There is a compatibility question regarding the GET_MP_STATE ioctl. Since older userspace does not know about the new KVM_MP_STATE_HALTED, we cannot return that, otherwise we'll break their mp_state support. Not a risk at the moment because we don't return to userspace with HALTED state (WFI and PSCI both stay in the run loop until the suspend request is consumed). But I'm not 100% sure of that and it will certainly change in the future. I'd rather explicitly return RUNNABLE in GET_MP_STATE, but I kept it simple for the moment - we'll probably toss the patch anyway. --- arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/kvm/arm.c | 18 ++++++++++++++- arch/arm64/kvm/handle_exit.c | 3 +-- arch/arm64/kvm/psci.c | 37 +++++++++++++------------------ 4 files changed, 35 insertions(+), 25 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 55a04f4d5919..3ca732feb9a5 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -46,6 +46,7 @@ #define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(2) #define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3) #define KVM_REQ_RELOAD_GICv4 KVM_ARCH_REQ(4) +#define KVM_REQ_SUSPEND KVM_ARCH_REQ(5)
#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \ KVM_DIRTY_LOG_INITIALLY_SET) @@ -722,6 +723,7 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr); void kvm_arm_vcpu_power_off(struct kvm_vcpu *vcpu); bool kvm_arm_vcpu_is_off(struct kvm_vcpu *vcpu); +void kvm_arm_vcpu_suspend(struct kvm_vcpu *vcpu);
/* Guest/host FPSIMD coordination helpers */ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index e4a8bf1b638b..4a42d54299db 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -447,6 +447,12 @@ bool kvm_arm_vcpu_is_off(struct kvm_vcpu *vcpu) return vcpu->arch.mp_state == KVM_MP_STATE_STOPPED; }
+void kvm_arm_vcpu_suspend(struct kvm_vcpu *vcpu) +{ + vcpu->arch.mp_state = KVM_MP_STATE_HALTED; + kvm_make_request(KVM_REQ_SUSPEND, vcpu); +} + int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, struct kvm_mp_state *mp_state) { @@ -667,6 +673,8 @@ static int kvm_vcpu_initialized(struct kvm_vcpu *vcpu)
static void check_vcpu_requests(struct kvm_vcpu *vcpu) { + bool irq_pending; + if (kvm_request_pending(vcpu)) { if (kvm_check_request(KVM_REQ_SLEEP, vcpu)) vcpu_req_sleep(vcpu); @@ -678,7 +686,7 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) * Clear IRQ_PENDING requests that were made to guarantee * that a VCPU sees new virtual interrupts. */ - kvm_check_request(KVM_REQ_IRQ_PENDING, vcpu); + irq_pending = kvm_check_request(KVM_REQ_IRQ_PENDING, vcpu);
if (kvm_check_request(KVM_REQ_RECORD_STEAL, vcpu)) kvm_update_stolen_time(vcpu); @@ -690,6 +698,14 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) vgic_v4_load(vcpu); preempt_enable(); } + + if (kvm_check_request(KVM_REQ_SUSPEND, vcpu)) { + if (!irq_pending) { + kvm_vcpu_block(vcpu); + kvm_clear_request(KVM_REQ_UNHALT, vcpu); + } + vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; + } } }
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index 6f48336b1d86..9717df3104cf 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -95,8 +95,7 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu) } else { 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_arm_vcpu_suspend(vcpu); }
kvm_incr_pc(vcpu); diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c index 24b4a2265dbd..42a307ceb95f 100644 --- a/arch/arm64/kvm/psci.c +++ b/arch/arm64/kvm/psci.c @@ -31,27 +31,6 @@ static unsigned long psci_affinity_mask(unsigned long affinity_level) return 0; }
-static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu) -{ - /* - * NOTE: For simplicity, we make VCPU suspend emulation to be - * same-as WFI (Wait-for-interrupt) emulation. - * - * This means for KVM the wakeup events are interrupts and - * this is consistent with intended use of StateID as described - * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). - * - * Further, we also treat power-down request to be same as - * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2 - * specification (ARM DEN 0022A). This means all suspend states - * for KVM will preserve the register state. - */ - kvm_vcpu_block(vcpu); - kvm_clear_request(KVM_REQ_UNHALT, vcpu); - - return PSCI_RET_SUCCESS; -} - static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) { struct vcpu_reset_state *reset_state; @@ -227,7 +206,21 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu) break; case PSCI_0_2_FN_CPU_SUSPEND: case PSCI_0_2_FN64_CPU_SUSPEND: - val = kvm_psci_vcpu_suspend(vcpu); + /* + * NOTE: For simplicity, we make VCPU suspend emulation to be + * same-as WFI (Wait-for-interrupt) emulation. + * + * This means for KVM the wakeup events are interrupts and this + * is consistent with intended use of StateID as described in + * section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A). + * + * Further, we also treat power-down request to be same as + * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2 + * specification (ARM DEN 0022A). This means all suspend states + * for KVM will preserve the register state. + */ + kvm_arm_vcpu_suspend(vcpu); + val = PSCI_RET_SUCCESS; break; case PSCI_0_2_FN_CPU_OFF: kvm_arm_vcpu_power_off(vcpu);