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@@ -968,6 +968,70 @@ struct kvm_xcrs {
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This ioctl would set vcpu's xcr to the value userspace specified.
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+4.45 KVM_GET_SUPPORTED_CPUID
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+
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+Capability: KVM_CAP_EXT_CPUID
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+Architectures: x86
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+Type: system ioctl
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+Parameters: struct kvm_cpuid2 (in/out)
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+Returns: 0 on success, -1 on error
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+
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+struct kvm_cpuid2 {
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+ __u32 nent;
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+ __u32 padding;
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+ struct kvm_cpuid_entry2 entries[0];
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+};
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+
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+#define KVM_CPUID_FLAG_SIGNIFCANT_INDEX 1
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+#define KVM_CPUID_FLAG_STATEFUL_FUNC 2
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+#define KVM_CPUID_FLAG_STATE_READ_NEXT 4
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+
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+struct kvm_cpuid_entry2 {
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+ __u32 function;
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+ __u32 index;
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+ __u32 flags;
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+ __u32 eax;
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+ __u32 ebx;
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+ __u32 ecx;
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+ __u32 edx;
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+ __u32 padding[3];
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+};
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+
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+This ioctl returns x86 cpuid features which are supported by both the hardware
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+and kvm. Userspace can use the information returned by this ioctl to
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+construct cpuid information (for KVM_SET_CPUID2) that is consistent with
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+hardware, kernel, and userspace capabilities, and with user requirements (for
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+example, the user may wish to constrain cpuid to emulate older hardware,
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+or for feature consistency across a cluster).
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+
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+Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure
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+with the 'nent' field indicating the number of entries in the variable-size
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+array 'entries'. If the number of entries is too low to describe the cpu
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+capabilities, an error (E2BIG) is returned. If the number is too high,
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+the 'nent' field is adjusted and an error (ENOMEM) is returned. If the
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+number is just right, the 'nent' field is adjusted to the number of valid
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+entries in the 'entries' array, which is then filled.
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+
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+The entries returned are the host cpuid as returned by the cpuid instruction,
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+with unknown or unsupported features masked out. The fields in each entry
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+are defined as follows:
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+
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+ function: the eax value used to obtain the entry
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+ index: the ecx value used to obtain the entry (for entries that are
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+ affected by ecx)
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+ flags: an OR of zero or more of the following:
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+ KVM_CPUID_FLAG_SIGNIFCANT_INDEX:
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+ if the index field is valid
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+ KVM_CPUID_FLAG_STATEFUL_FUNC:
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+ if cpuid for this function returns different values for successive
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+ invocations; there will be several entries with the same function,
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+ all with this flag set
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+ KVM_CPUID_FLAG_STATE_READ_NEXT:
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+ for KVM_CPUID_FLAG_STATEFUL_FUNC entries, set if this entry is
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+ the first entry to be read by a cpu
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+ eax, ebx, ecx, edx: the values returned by the cpuid instruction for
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+ this function/index combination
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+
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5. The kvm_run structure
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Application code obtains a pointer to the kvm_run structure by
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Avi Kivity