Commit a3064257 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

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



Refresh comments about msrs_to_save, emulated_msrs, and msr_based_features
to remove stale references left behind by commit 2374b731 (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: default avatarBinbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20230607004636.1421424-1-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent e12fa4b9

arch/x86/kvm/x86.c

+13 −14
Original line number Diff line number Diff line
@@ -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,