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| author | David Matlack <dmatlack@google.com> | 2020-04-17 15:14:46 -0700 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-04-24 12:53:17 -0400 |
| commit | acd05785e48c01edb2c4f4d014d28478b5f19fb5 (patch) | |
| tree | c8a7003b579cbdc7c79d109ec563f84de7d07018 /virt | |
| parent | 87796555d48ca1cc681515e065b824ecab9c4282 (diff) | |
| download | lwn-acd05785e48c01edb2c4f4d014d28478b5f19fb5.tar.gz lwn-acd05785e48c01edb2c4f4d014d28478b5f19fb5.zip | |
kvm: add capability for halt polling
KVM_CAP_HALT_POLL is a per-VM capability that lets userspace
control the halt-polling time, allowing halt-polling to be tuned or
disabled on particular VMs.
With dynamic halt-polling, a VM's VCPUs can poll from anywhere from
[0, halt_poll_ns] on each halt. KVM_CAP_HALT_POLL sets the
upper limit on the poll time.
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jon Cargille <jcargill@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-Id: <20200417221446.108733-1-jcargill@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 19 |
1 files changed, 15 insertions, 4 deletions
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); } |