diff options
Diffstat (limited to 'Documentation/virt/kvm')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 15 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/vm.rst | 3 | ||||
| -rw-r--r-- | Documentation/virt/kvm/halt-polling.rst (renamed from Documentation/virt/kvm/x86/halt-polling.rst) | 13 | ||||
| -rw-r--r-- | Documentation/virt/kvm/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/virt/kvm/x86/index.rst | 1 |
5 files changed, 24 insertions, 9 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index eee9f857a986..896914e3a847 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -7213,14 +7213,13 @@ veto the transition. :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. +KVM_CAP_HALT_POLL overrides the kvm.halt_poll_ns module parameter to set the +maximum halt-polling time for all vCPUs in the target VM. This capability can +be invoked at any time and any number of times to dynamically change the +maximum halt-polling time. + +See Documentation/virt/kvm/halt-polling.rst for more information on halt +polling. 7.21 KVM_CAP_X86_USER_SPACE_MSR ------------------------------- diff --git a/Documentation/virt/kvm/devices/vm.rst b/Documentation/virt/kvm/devices/vm.rst index 0aa5b1cfd700..60acc39e0e93 100644 --- a/Documentation/virt/kvm/devices/vm.rst +++ b/Documentation/virt/kvm/devices/vm.rst @@ -215,6 +215,7 @@ KVM_S390_VM_TOD_EXT). :Parameters: address of a buffer in user space to store the data (u8) to :Returns: -EFAULT if the given address is not accessible from kernel space; -EINVAL if setting the TOD clock extension to != 0 is not supported + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) 3.2. ATTRIBUTE: KVM_S390_VM_TOD_LOW ----------------------------------- @@ -224,6 +225,7 @@ the POP (u64). :Parameters: address of a buffer in user space to store the data (u64) to :Returns: -EFAULT if the given address is not accessible from kernel space + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) 3.3. ATTRIBUTE: KVM_S390_VM_TOD_EXT ----------------------------------- @@ -237,6 +239,7 @@ it, it is stored as 0 and not allowed to be set to a value != 0. (kvm_s390_vm_tod_clock) to :Returns: -EFAULT if the given address is not accessible from kernel space; -EINVAL if setting the TOD clock extension to != 0 is not supported + -EOPNOTSUPP for a PV guest (TOD managed by the ultravisor) 4. GROUP: KVM_S390_VM_CRYPTO ============================ diff --git a/Documentation/virt/kvm/x86/halt-polling.rst b/Documentation/virt/kvm/halt-polling.rst index 4922e4a15f18..3fae39b1a5ba 100644 --- a/Documentation/virt/kvm/x86/halt-polling.rst +++ b/Documentation/virt/kvm/halt-polling.rst @@ -119,6 +119,19 @@ These module parameters can be set from the debugfs files in: Note: that these module parameters are system wide values and are not able to be tuned on a per vm basis. +Any changes to these parameters will be picked up by new and existing vCPUs the +next time they halt, with the notable exception of VMs using KVM_CAP_HALT_POLL +(see next section). + +KVM_CAP_HALT_POLL +================= + +KVM_CAP_HALT_POLL is a VM capability that allows userspace to override halt_poll_ns +on a per-VM basis. VMs using KVM_CAP_HALT_POLL ignore halt_poll_ns completely (but +still obey halt_poll_ns_grow, halt_poll_ns_grow_start, and halt_poll_ns_shrink). + +See Documentation/virt/kvm/api.rst for more information on this capability. + Further Notes ============= diff --git a/Documentation/virt/kvm/index.rst b/Documentation/virt/kvm/index.rst index e0a2c74e1043..ad13ec55ddfe 100644 --- a/Documentation/virt/kvm/index.rst +++ b/Documentation/virt/kvm/index.rst @@ -17,4 +17,5 @@ KVM locking vcpu-requests + halt-polling review-checklist diff --git a/Documentation/virt/kvm/x86/index.rst b/Documentation/virt/kvm/x86/index.rst index 7ff588826b9f..9ece6b8dc817 100644 --- a/Documentation/virt/kvm/x86/index.rst +++ b/Documentation/virt/kvm/x86/index.rst @@ -10,7 +10,6 @@ KVM for x86 systems amd-memory-encryption cpuid errata - halt-polling hypercalls mmu msr |