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KVM: x86: Update KVM-only leaf handling to allow for 100% KVM-only leafs

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Rename kvm_cpu_cap_init_scattered() to kvm_cpu_cap_init_kvm_defined() in
anticipation of adding KVM-only CPUID leafs that aren't recognized by the
kernel and thus not scattered, i.e. for leafs that are 100% KVM-defined.

Adjust/add comments to kvm_only_cpuid_leafs and KVM_X86_FEATURE to
document how to create new kvm_only_cpuid_leafs entries for scattered
features as well as features that are entirely unknown to the kernel.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221125125845.1182922-3-jiaxi.chen@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2022-11-25 20:58:39 +08:00 committed by Paolo Bonzini
parent c4690d0161
commit 047c722990
2 changed files with 19 additions and 7 deletions
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8
arch/x86/kvm/cpuid.c
View File

@ -549,9 +549,9 @@ static __always_inline void __kvm_cpu_cap_mask(unsigned int leaf)
}
static __always_inline
void kvm_cpu_cap_init_scattered(enum kvm_only_cpuid_leafs leaf, u32 mask)
void kvm_cpu_cap_init_kvm_defined(enum kvm_only_cpuid_leafs leaf, u32 mask)
{
/* Use kvm_cpu_cap_mask for non-scattered leafs. */
/* Use kvm_cpu_cap_mask for leafs that aren't KVM-only. */
BUILD_BUG_ON(leaf < NCAPINTS);
kvm_cpu_caps[leaf] = mask;
@ -561,7 +561,7 @@ void kvm_cpu_cap_init_scattered(enum kvm_only_cpuid_leafs leaf, u32 mask)
static __always_inline void kvm_cpu_cap_mask(enum cpuid_leafs leaf, u32 mask)
{
/* Use kvm_cpu_cap_init_scattered for scattered leafs. */
/* Use kvm_cpu_cap_init_kvm_defined for KVM-only leafs. */
BUILD_BUG_ON(leaf >= NCAPINTS);
kvm_cpu_caps[leaf] &= mask;
@ -670,7 +670,7 @@ void kvm_set_cpu_caps(void)
F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd
);
kvm_cpu_cap_init_scattered(CPUID_12_EAX,
kvm_cpu_cap_init_kvm_defined(CPUID_12_EAX,
SF(SGX1) | SF(SGX2)
);

18
arch/x86/kvm/reverse_cpuid.h
View File

@ -7,9 +7,9 @@
#include <asm/cpufeatures.h>
/*
* Hardware-defined CPUID leafs that are scattered in the kernel, but need to
* be directly used by KVM. Note, these word values conflict with the kernel's
* "bug" caps, but KVM doesn't use those.
* Hardware-defined CPUID leafs that are either scattered by the kernel or are
* unknown to the kernel, but need to be directly used by KVM. Note, these
* word values conflict with the kernel's "bug" caps, but KVM doesn't use those.
*/
enum kvm_only_cpuid_leafs {
CPUID_12_EAX = NCAPINTS,
@ -18,6 +18,18 @@ enum kvm_only_cpuid_leafs {
NKVMCAPINTS = NR_KVM_CPU_CAPS - NCAPINTS,
};
/*
* Define a KVM-only feature flag.
*
* For features that are scattered by cpufeatures.h, __feature_translate() also
* needs to be updated to translate the kernel-defined feature into the
* KVM-defined feature.
*
* For features that are 100% KVM-only, i.e. not defined by cpufeatures.h,
* forego the intermediate KVM_X86_FEATURE and directly define X86_FEATURE_* so
* that X86_FEATURE_* can be used in KVM. No __feature_translate() handling is
* needed in this case.
*/
#define KVM_X86_FEATURE(w, f) ((w)*32 + (f))
/* Intel-defined SGX sub-features, CPUID level 0x12 (EAX). */