To help userspace implement PSCI CPU_SUSPEND, allow setting the "HALTED" MP state to request a WFI before returning to the guest.
Userspace won't obtain a HALTED mp_state from a KVM_GET_MP_STATE call unless they set it themselves. When set by KVM, to handle wfi or CPU_SUSPEND, it is consumed before returning to userspace. Signed-off-by: Jean-Philippe Brucker <[email protected]> --- Documentation/virt/kvm/api.rst | 15 +++++++++------ include/uapi/linux/kvm.h | 1 + arch/arm64/kvm/arm.c | 11 ++++++++++- 3 files changed, 20 insertions(+), 7 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 7fcb2fd38f42..e4fe7fb60d5d 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1416,8 +1416,8 @@ Possible values are: which has not yet received an INIT signal [x86] KVM_MP_STATE_INIT_RECEIVED the vcpu has received an INIT signal, and is now ready for a SIPI [x86] - KVM_MP_STATE_HALTED the vcpu has executed a HLT instruction and - is waiting for an interrupt [x86] + KVM_MP_STATE_HALTED the vcpu has executed a HLT/WFI instruction + and is waiting for an interrupt [x86,arm64] KVM_MP_STATE_SIPI_RECEIVED the vcpu has just received a SIPI (vector accessible via KVM_GET_VCPU_EVENTS) [x86] KVM_MP_STATE_STOPPED the vcpu is stopped [s390,arm/arm64] @@ -1435,8 +1435,9 @@ these architectures. For arm/arm64: ^^^^^^^^^^^^^^ -The only states that are valid are KVM_MP_STATE_STOPPED and -KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not. +Valid states are KVM_MP_STATE_STOPPED and KVM_MP_STATE_RUNNABLE which reflect +if the vcpu is paused or not. If KVM_CAP_ARM_MP_HALTED is present, state +KVM_MP_STATE_HALTED is also valid. 4.39 KVM_SET_MP_STATE --------------------- @@ -1457,8 +1458,10 @@ these architectures. For arm/arm64: ^^^^^^^^^^^^^^ -The only states that are valid are KVM_MP_STATE_STOPPED and -KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not. +Valid states are KVM_MP_STATE_STOPPED and KVM_MP_STATE_RUNNABLE which reflect +if the vcpu should be paused or not. If KVM_CAP_ARM_MP_HALTED is present, +KVM_MP_STATE_HALTED can be set, to wait for interrupts targeted at the vcpu +before running it. 4.40 KVM_SET_IDENTITY_MAP_ADDR ------------------------------ diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 79d9c44d1ad7..06ba64c49737 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1083,6 +1083,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_SGX_ATTRIBUTE 196 #define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197 #define KVM_CAP_PTP_KVM 198 +#define KVM_CAP_ARM_MP_HALTED 199 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index d8cbaa0373c7..d6ad977fea5f 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -207,6 +207,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_SET_GUEST_DEBUG: case KVM_CAP_VCPU_ATTRIBUTES: case KVM_CAP_PTP_KVM: + case KVM_CAP_ARM_MP_HALTED: r = 1; break; case KVM_CAP_SET_GUEST_DEBUG2: @@ -469,6 +470,9 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, case KVM_MP_STATE_RUNNABLE: vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; break; + case KVM_MP_STATE_HALTED: + kvm_arm_vcpu_suspend(vcpu); + break; case KVM_MP_STATE_STOPPED: kvm_arm_vcpu_power_off(vcpu); break; @@ -699,7 +703,12 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) preempt_enable(); } - if (kvm_check_request(KVM_REQ_SUSPEND, vcpu)) { + /* + * Check mp_state again in case userspace changed their mind + * after requesting suspend. + */ + if (kvm_check_request(KVM_REQ_SUSPEND, vcpu) && + vcpu->arch.mp_state == KVM_MP_STATE_HALTED) { if (!irq_pending) { kvm_vcpu_block(vcpu); kvm_clear_request(KVM_REQ_UNHALT, vcpu); -- 2.31.1 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
