diff options
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 17 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 19 |
4 files changed, 34 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index efbbe570aa9b..d871dacb984e 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -5802,6 +5802,23 @@ If present, this capability can be enabled for a VM, meaning that KVM will allow the transition to secure guest mode. Otherwise KVM will veto the transition. +7.20 KVM_CAP_HALT_POLL +---------------------- + +:Architectures: all +:Target: VM +:Parameters: args[0] is the maximum poll time in nanoseconds +:Returns: 0 on success; -1 on error + +This capability overrides the kvm module parameter halt_poll_ns for the +target VM. + +VCPU polling allows a VCPU to poll for wakeup events instead of immediately +scheduling during guest halts. The maximum time a VCPU can spend polling is +controlled by the kvm module parameter halt_poll_ns. This capability allows +the maximum halt time to specified on a per-VM basis, effectively overriding +the module parameter for the target VM. + 8. Other capabilities. ====================== diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 5285a5568208..3cc6ccbb1183 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -503,6 +503,7 @@ struct kvm { struct srcu_struct srcu; struct srcu_struct irq_srcu; pid_t userspace_pid; + unsigned int max_halt_poll_ns; }; #define kvm_err(fmt, ...) \ diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 428c7dde6b4b..ac9eba0289d1 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1017,6 +1017,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_S390_VCPU_RESETS 179 #define KVM_CAP_S390_PROTECTED 180 #define KVM_CAP_PPC_SECURE_GUEST 181 +#define KVM_CAP_HALT_POLL 182 #ifdef KVM_CAP_IRQ_ROUTING diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e7436d054305..33e1eee96f75 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -710,6 +710,8 @@ static struct kvm *kvm_create_vm(unsigned long type) goto out_err_no_arch_destroy_vm; } + kvm->max_halt_poll_ns = halt_poll_ns; + r = kvm_arch_init_vm(kvm, type); if (r) goto out_err_no_arch_destroy_vm; @@ -2713,15 +2715,16 @@ out: if (!kvm_arch_no_poll(vcpu)) { if (!vcpu_valid_wakeup(vcpu)) { shrink_halt_poll_ns(vcpu); - } else if (halt_poll_ns) { + } else if (vcpu->kvm->max_halt_poll_ns) { if (block_ns <= vcpu->halt_poll_ns) ; /* we had a long block, shrink polling */ - else if (vcpu->halt_poll_ns && block_ns > halt_poll_ns) + else if (vcpu->halt_poll_ns && + block_ns > vcpu->kvm->max_halt_poll_ns) shrink_halt_poll_ns(vcpu); /* we had a short halt and our poll time is too small */ - else if (vcpu->halt_poll_ns < halt_poll_ns && - block_ns < halt_poll_ns) + else if (vcpu->halt_poll_ns < vcpu->kvm->max_halt_poll_ns && + block_ns < vcpu->kvm->max_halt_poll_ns) grow_halt_poll_ns(vcpu); } else { vcpu->halt_poll_ns = 0; @@ -3510,6 +3513,7 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_IOEVENTFD_ANY_LENGTH: case KVM_CAP_CHECK_EXTENSION_VM: case KVM_CAP_ENABLE_CAP_VM: + case KVM_CAP_HALT_POLL: return 1; #ifdef CONFIG_KVM_MMIO case KVM_CAP_COALESCED_MMIO: @@ -3560,6 +3564,13 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm, return 0; } #endif + case KVM_CAP_HALT_POLL: { + if (cap->flags || cap->args[0] != (unsigned int)cap->args[0]) + return -EINVAL; + + kvm->max_halt_poll_ns = cap->args[0]; + return 0; + } default: return kvm_vm_ioctl_enable_cap(kvm, cap); } |