summaryrefslogtreecommitdiff
path: root/Documentation/virt
diff options
context:
space:
mode:
authorVitaly Kuznetsov <vkuznets@redhat.com>2020-09-29 17:09:43 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2020-11-15 09:49:11 -0500
commitc21d54f0307ff42a346294899107b570b98c47b5 (patch)
tree4a1f60de45aacaec33058ec3cd4c8712b3d8cabd /Documentation/virt
parentb59e00dd8cda75fc8303c9f6847ac720b10664e3 (diff)
KVM: x86: hyper-v: allow KVM_GET_SUPPORTED_HV_CPUID as a system ioctl
KVM_GET_SUPPORTED_HV_CPUID is a vCPU ioctl but its output is now independent from vCPU and in some cases VMMs may want to use it as a system ioctl instead. In particular, QEMU doesn CPU feature expansion before any vCPU gets created so KVM_GET_SUPPORTED_HV_CPUID can't be used. Convert KVM_GET_SUPPORTED_HV_CPUID to 'dual' system/vCPU ioctl with the same meaning. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Message-Id: <20200929150944.1235688-2-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virt')
-rw-r--r--Documentation/virt/kvm/api.rst16
1 files changed, 11 insertions, 5 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e00a66d72372..81d54fe76a2d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4455,9 +4455,9 @@ that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is present.
4.118 KVM_GET_SUPPORTED_HV_CPUID
--------------------------------
-:Capability: KVM_CAP_HYPERV_CPUID
+:Capability: KVM_CAP_HYPERV_CPUID (vcpu), KVM_CAP_SYS_HYPERV_CPUID (system)
:Architectures: x86
-:Type: vcpu ioctl
+:Type: system ioctl, vcpu ioctl
:Parameters: struct kvm_cpuid2 (in/out)
:Returns: 0 on success, -1 on error
@@ -4502,9 +4502,6 @@ Currently, the following list of CPUID leaves are returned:
- HYPERV_CPUID_SYNDBG_INTERFACE
- HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES
-HYPERV_CPUID_NESTED_FEATURES leaf is only exposed when Enlightened VMCS was
-enabled on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).
-
Userspace invokes KVM_GET_SUPPORTED_HV_CPUID by passing a kvm_cpuid2 structure
with the 'nent' field indicating the number of entries in the variable-size
array 'entries'. If the number of entries is too low to describe all Hyper-V
@@ -4515,6 +4512,15 @@ number of valid entries in the 'entries' array, which is then filled.
'index' and 'flags' fields in 'struct kvm_cpuid_entry2' are currently reserved,
userspace should not expect to get any particular value there.
+Note, vcpu version of KVM_GET_SUPPORTED_HV_CPUID is currently deprecated. Unlike
+system ioctl which exposes all supported feature bits unconditionally, vcpu
+version has the following quirks:
+- HYPERV_CPUID_NESTED_FEATURES leaf and HV_X64_ENLIGHTENED_VMCS_RECOMMENDED
+ feature bit are only exposed when Enlightened VMCS was previously enabled
+ on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).
+- HV_STIMER_DIRECT_MODE_AVAILABLE bit is only exposed with in-kernel LAPIC.
+ (presumes KVM_CREATE_IRQCHIP has already been called).
+
4.119 KVM_ARM_VCPU_FINALIZE
---------------------------