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| author | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-26 07:49:45 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2022-01-28 07:33:32 -0500 |
| commit | dd6e631220181162478984d2d46dd979e04d8e75 (patch) | |
| tree | 979a5f35f1614f6347bb26807174487ba4f6875b /Documentation | |
| parent | 56f289a8d23addfa4408a08f07f42fcfe2a7bd69 (diff) | |
| download | lwn-dd6e631220181162478984d2d46dd979e04d8e75.tar.gz lwn-dd6e631220181162478984d2d46dd979e04d8e75.zip | |
KVM: x86: add system attribute to retrieve full set of supported xsave states
Because KVM_GET_SUPPORTED_CPUID is meant to be passed (by simple-minded
VMMs) to KVM_SET_CPUID2, it cannot include any dynamic xsave states that
have not been enabled. Probing those, for example so that they can be
passed to ARCH_REQ_XCOMP_GUEST_PERM, requires a new ioctl or arch_prctl.
The latter is in fact worse, even though that is what the rest of the
API uses, because it would require supported_xcr0 to be moved from the
KVM module to the kernel just for this use. In addition, the value
would be nonsensical (or an error would have to be returned) until
the KVM module is loaded in.
Therefore, to limit the growth of system ioctls, add a /dev/kvm
variant of KVM_{GET,HAS}_DEVICE_ATTR, and implement it in x86
with just one group (0) and attribute (KVM_X86_XCOMP_GUEST_SUPP).
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index bb8cfddbb22d..a4267104db50 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -3268,6 +3268,7 @@ number. :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device, KVM_CAP_VCPU_ATTRIBUTES for vcpu device + KVM_CAP_SYS_ATTRIBUTES for system (/dev/kvm) device (no set) :Type: device ioctl, vm ioctl, vcpu ioctl :Parameters: struct kvm_device_attr :Returns: 0 on success, -1 on error @@ -3302,7 +3303,8 @@ transferred is defined by the particular attribute. ------------------------ :Capability: KVM_CAP_DEVICE_CTRL, KVM_CAP_VM_ATTRIBUTES for vm device, - KVM_CAP_VCPU_ATTRIBUTES for vcpu device + KVM_CAP_VCPU_ATTRIBUTES for vcpu device + KVM_CAP_SYS_ATTRIBUTES for system (/dev/kvm) device :Type: device ioctl, vm ioctl, vcpu ioctl :Parameters: struct kvm_device_attr :Returns: 0 on success, -1 on error |