[PATCH 4/5] KVM: arm/arm64: Implement PSCI ON_PENDING when turning on VCPUs
From: Christoffer Dall <hidden>
Date: 2019-01-25 09:48:35
Also in:
kvm, kvmarm
Subsystem:
arm port, arm64 port (aarch64 architecture), kernel virtual machine (kvm), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Russell King, Catalin Marinas, Will Deacon, Paolo Bonzini, Marc Zyngier, Oliver Upton, Linus Torvalds
We are currently not implementing the PSCI spec completely, as we do not take handle the situation where two VCPUs are attempting to turn on a third VCPU at the same time. The PSCI implementation should make sure that only one requesting VCPU wins the race and that the other receives PSCI_RET_ON_PENDING. Implement this by changing the VCPU power state to a tristate enum and ensure only a single VCPU can turn on another VCPU at a given time using a cmpxchg operation. Signed-off-by: Christoffer Dall <redacted> Acked-by: Marc Zyngier <redacted> --- arch/arm/include/asm/kvm_host.h | 10 ++++++++-- arch/arm64/include/asm/kvm_host.h | 10 ++++++++-- virt/kvm/arm/arm.c | 24 +++++++++++++++--------- virt/kvm/arm/psci.c | 21 ++++++++++++++------- 4 files changed, 45 insertions(+), 20 deletions(-)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index b1cfae222441..4dc47fea1ac8 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h@@ -157,6 +157,12 @@ struct vcpu_reset_state { bool reset; }; +enum vcpu_power_state { + KVM_ARM_VCPU_OFF, + KVM_ARM_VCPU_ON_PENDING, + KVM_ARM_VCPU_ON, +}; + struct kvm_vcpu_arch { struct kvm_cpu_context ctxt;
@@ -184,8 +190,8 @@ struct kvm_vcpu_arch { * here. */ - /* vcpu power-off state */ - bool power_off; + /* vcpu power state */ + enum vcpu_power_state power_state; /* Don't run the guest (internal implementation need) */ bool pause;
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index d43b13421987..0647a409657b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h@@ -218,6 +218,12 @@ struct vcpu_reset_state { bool reset; }; +enum vcpu_power_state { + KVM_ARM_VCPU_OFF, + KVM_ARM_VCPU_ON_PENDING, + KVM_ARM_VCPU_ON, +}; + struct kvm_vcpu_arch { struct kvm_cpu_context ctxt;
@@ -285,8 +291,8 @@ struct kvm_vcpu_arch { u32 mdscr_el1; } guest_debug_preserved; - /* vcpu power-off state */ - bool power_off; + /* vcpu power state */ + enum vcpu_power_state power_state; /* Don't run the guest (internal implementation need) */ bool pause;
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 785076176814..1e3195155860 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c@@ -411,7 +411,7 @@ static void vcpu_power_off(struct kvm_vcpu *vcpu) int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, struct kvm_mp_state *mp_state) { - if (vcpu->arch.power_off) + if (vcpu->arch.power_state != KVM_ARM_VCPU_ON) mp_state->mp_state = KVM_MP_STATE_STOPPED; else mp_state->mp_state = KVM_MP_STATE_RUNNABLE;
@@ -426,7 +426,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, switch (mp_state->mp_state) { case KVM_MP_STATE_RUNNABLE: - vcpu->arch.power_off = false; + vcpu->arch.power_state = KVM_ARM_VCPU_ON; break; case KVM_MP_STATE_STOPPED: vcpu_power_off(vcpu);
@@ -448,8 +448,9 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) { bool irq_lines = *vcpu_hcr(v) & (HCR_VI | HCR_VF); - return ((irq_lines || kvm_vgic_vcpu_pending_irq(v)) - && !v->arch.power_off && !v->arch.pause); + return (irq_lines || kvm_vgic_vcpu_pending_irq(v)) && + v->arch.power_state == KVM_ARM_VCPU_ON && + !v->arch.pause; } bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu)
@@ -614,14 +615,19 @@ void kvm_arm_resume_guest(struct kvm *kvm) } } +static bool vcpu_sleeping(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.power_state != KVM_ARM_VCPU_ON || + vcpu->arch.pause; +} + static void vcpu_req_sleep(struct kvm_vcpu *vcpu) { struct swait_queue_head *wq = kvm_arch_vcpu_wq(vcpu); - swait_event_interruptible_exclusive(*wq, ((!vcpu->arch.power_off) && - (!vcpu->arch.pause))); + swait_event_interruptible_exclusive(*wq, !vcpu_sleeping(vcpu)); - if (vcpu->arch.power_off || vcpu->arch.pause) { + if (vcpu_sleeping(vcpu)) { /* Awaken to handle a signal, request we sleep again later. */ kvm_make_request(KVM_REQ_SLEEP, vcpu); }
@@ -646,7 +652,7 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) vcpu_req_sleep(vcpu); if (kvm_check_request(KVM_REQ_VCPU_OFF, vcpu)) { - vcpu->arch.power_off = true; + vcpu->arch.power_state = KVM_ARM_VCPU_OFF; vcpu_req_sleep(vcpu); }
@@ -1016,7 +1022,7 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu, if (test_bit(KVM_ARM_VCPU_POWER_OFF, vcpu->arch.features)) vcpu_power_off(vcpu); else - vcpu->arch.power_off = false; + vcpu->arch.power_state = KVM_ARM_VCPU_ON; return 0; }
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 20255319e193..5c2d9eeb810c 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c@@ -106,6 +106,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) struct kvm *kvm = source_vcpu->kvm; struct kvm_vcpu *vcpu = NULL; unsigned long cpu_id; + enum vcpu_power_state old_power_state; cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK; if (vcpu_mode_is_32bit(source_vcpu))
@@ -119,12 +120,18 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) */ if (!vcpu) return PSCI_RET_INVALID_PARAMS; - if (!vcpu->arch.power_off) { - if (kvm_psci_version(source_vcpu, kvm) != KVM_ARM_PSCI_0_1) - return PSCI_RET_ALREADY_ON; - else + old_power_state = cmpxchg(&vcpu->arch.power_state, + KVM_ARM_VCPU_OFF, + KVM_ARM_VCPU_ON_PENDING); + + if (old_power_state != KVM_ARM_VCPU_OFF && + kvm_psci_version(source_vcpu, kvm) == KVM_ARM_PSCI_0_1) return PSCI_RET_INVALID_PARAMS; - } + + if (old_power_state == KVM_ARM_VCPU_ON_PENDING) + return PSCI_RET_ON_PENDING; + else if (old_power_state == KVM_ARM_VCPU_ON) + return PSCI_RET_ALREADY_ON; reset_state = &vcpu->arch.reset_state;
@@ -148,7 +155,7 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu) */ smp_wmb(); - vcpu->arch.power_off = false; + vcpu->arch.power_state = KVM_ARM_VCPU_ON; kvm_vcpu_wake_up(vcpu); return PSCI_RET_SUCCESS;
@@ -183,7 +190,7 @@ static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu) mpidr = kvm_vcpu_get_mpidr_aff(tmp); if ((mpidr & target_affinity_mask) == target_affinity) { matching_cpus++; - if (!tmp->arch.power_off) + if (tmp->arch.power_state == KVM_ARM_VCPU_ON) return PSCI_0_2_AFFINITY_LEVEL_ON; } }
--
2.18.0
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