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KVM: x86: Update comments about MSR lists exposed to userspace

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Refresh comments about msrs_to_save, emulated_msrs, and msr_based_features
to remove stale references left behind by commit 2374b7310b (KVM:
x86/pmu: Use separate array for defining "PMU MSRs to save"), and to
better reflect the current reality, e.g. emulated_msrs is no longer just
for MSRs that are "kvm-specific".

Reported-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20230607004636.1421424-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-06-06 17:46:36 -07:00
parent e12fa4b92a
commit a306425708
1 changed files with 13 additions and 14 deletions
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27
arch/x86/kvm/x86.c
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@ -1423,15 +1423,14 @@ int kvm_emulate_rdpmc(struct kvm_vcpu *vcpu)
EXPORT_SYMBOL_GPL(kvm_emulate_rdpmc);
/*
* List of msr numbers which we expose to userspace through KVM_GET_MSRS
* and KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST.
*
* The three MSR lists(msrs_to_save, emulated_msrs, msr_based_features)
* extract the supported MSRs from the related const lists.
* msrs_to_save is selected from the msrs_to_save_all to reflect the
* capabilities of the host cpu. This capabilities test skips MSRs that are
* kvm-specific. Those are put in emulated_msrs_all; filtering of emulated_msrs
* may depend on host virtualization features rather than host cpu features.
* The three MSR lists(msrs_to_save, emulated_msrs, msr_based_features) track
* the set of MSRs that KVM exposes to userspace through KVM_GET_MSRS,
* KVM_SET_MSRS, and KVM_GET_MSR_INDEX_LIST. msrs_to_save holds MSRs that
* require host support, i.e. should be probed via RDMSR. emulated_msrs holds
* MSRs that KVM emulates without strictly requiring host support.
* msr_based_features holds MSRs that enumerate features, i.e. are effectively
* CPUID leafs. Note, msr_based_features isn't mutually exclusive with
* msrs_to_save and emulated_msrs.
*/
static const u32 msrs_to_save_base[] = {
@ -1527,11 +1526,11 @@ static const u32 emulated_msrs_all[] = {
MSR_IA32_UCODE_REV,
/*
* The following list leaves out MSRs whose values are determined
* by arch/x86/kvm/vmx/nested.c based on CPUID or other MSRs.
* We always support the "true" VMX control MSRs, even if the host
* processor does not, so I am putting these registers here rather
* than in msrs_to_save_all.
* KVM always supports the "true" VMX control MSRs, even if the host
* does not. The VMX MSRs as a whole are considered "emulated" as KVM
* doesn't strictly require them to exist in the host (ignoring that
* KVM would refuse to load in the first place if the core set of MSRs
* aren't supported).
*/
MSR_IA32_VMX_BASIC,
MSR_IA32_VMX_TRUE_PINBASED_CTLS,