Prepare for WFI requests from userspace, by adding a suspend request and moving the WFI execution into check_vcpu_requests(), next to the power-off logic.
vcpu->arch.mp_state, previously only RUNNABLE or STOPPED, supports an additional state HALTED and two new state transitions: RUNNABLE -> HALTED from WFI or PSCI CPU_SUSPEND (same vCPU) HALTED -> RUNNABLE vGIC IRQ, pending timer, signal There shouldn't be any functional change with this patch, even though the KVM_GET_MP_STATE ioctl could now in theory return KVM_MP_STATE_HALTED, which would break some users' mp_state support. In practice it should not happen because we do not return to userspace with HALTED state. Both WFI and PSCI CPU_SUSPEND stay in the vCPU run loop until the suspend request is consumed. It does feel fragile though, maybe we should explicitly return RUNNABLE in KVM_GET_MP_STATE in place of HALTED, to prevent future breakage. Signed-off-by: Jean-Philippe Brucker <[email protected]> --- 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 bcc24adb9c0a..d8cbaa0373c7 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); -- 2.31.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
