From df9cb9cc5bcd36127a820c09b4c40adfdc17c547 Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Thu, 24 May 2018 11:59:54 -0700 Subject: kvm: x86: Amend the KVM_GET_SUPPORTED_CPUID API documentation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Document the subtle nuances that KVM_CAP_X86_DISABLE_EXITS induces in the KVM_GET_SUPPORTED_CPUID API. Fixes: 4d5422cea3b6 ("KVM: X86: Provide a capability to disable MWAIT intercepts") Signed-off-by: Jim Mattson Signed-off-by: Radim Krčmář --- Documentation/virtual/kvm/api.txt | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) (limited to 'Documentation') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index c563da4244da..495b7742ab58 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1269,12 +1269,18 @@ struct kvm_cpuid_entry2 { __u32 padding[3]; }; -This ioctl returns x86 cpuid features which are supported by both the hardware -and kvm. Userspace can use the information returned by this ioctl to -construct cpuid information (for KVM_SET_CPUID2) that is consistent with -hardware, kernel, and userspace capabilities, and with user requirements (for -example, the user may wish to constrain cpuid to emulate older hardware, -or for feature consistency across a cluster). +This ioctl returns x86 cpuid features which are supported by both the +hardware and kvm in its default configuration. Userspace can use the +information returned by this ioctl to construct cpuid information (for +KVM_SET_CPUID2) that is consistent with hardware, kernel, and +userspace capabilities, and with user requirements (for example, the +user may wish to constrain cpuid to emulate older hardware, or for +feature consistency across a cluster). + +Note that certain capabilities, such as KVM_CAP_X86_DISABLE_EXITS, may +expose cpuid features (e.g. MONITOR) which are not supported by kvm in +its default configuration. If userspace enables such capabilities, it +is responsible for modifying the results of this ioctl appropriately. Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure with the 'nent' field indicating the number of entries in the variable-size -- cgit