mainline inclusion
from mainline-v5.17-rc2
commit dd6e6312
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5RQLJ
CVE: NA

Intel-SIG: commit dd6e6312 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: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NLin Wang <lin.x.wang@intel.com>