Commit 447112d7 authored by Sean Christopherson's avatar Sean Christopherson
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KVM: VMX: Snapshot LBR capabilities during module initialization 



Snapshot VMX's LBR capabilities once during module initialization instead
of calling into perf every time a vCPU reconfigures its vPMU.  This will
allow massaging the LBR capabilities, e.g. if the CPU doesn't support
callstacks, without having to remember to update multiple locations.

Opportunistically tag vmx_get_perf_capabilities() with __init, as it's
only called from vmx_set_cpu_caps().

Reviewed-by: default avatarMingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20240307011344.835640-2-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 7f2817ef

arch/x86/kvm/vmx/pmu_intel.c

+1 −1
Original line number Diff line number Diff line
@@ -535,7 +535,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) 
	perf_capabilities = vcpu_get_perf_capabilities(vcpu);

	if (cpuid_model_is_consistent(vcpu) &&

	    (perf_capabilities & PMU_CAP_LBR_FMT))

		x86_perf_get_lbr(&lbr_desc->records);

		memcpy(&lbr_desc->records, &vmx_lbr_caps, sizeof(vmx_lbr_caps));

	else

		lbr_desc->records.nr = 0;

arch/x86/kvm/vmx/vmx.c

+5 −4
Original line number Diff line number Diff line
@@ -218,6 +218,8 @@ module_param(ple_window_max, uint, 0444); 
int __read_mostly pt_mode = PT_MODE_SYSTEM;

module_param(pt_mode, int, S_IRUGO);



struct x86_pmu_lbr __ro_after_init vmx_lbr_caps;



static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush);

static DEFINE_STATIC_KEY_FALSE(vmx_l1d_flush_cond);

static DEFINE_MUTEX(vmx_l1d_flush_mutex);
@@ -7862,10 +7864,9 @@ static void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) 
	vmx_update_exception_bitmap(vcpu);

}



static u64 vmx_get_perf_capabilities(void)

static __init u64 vmx_get_perf_capabilities(void)

{

	u64 perf_cap = PMU_CAP_FW_WRITES;

	struct x86_pmu_lbr lbr;

	u64 host_perf_cap = 0;



	if (!enable_pmu)
@@ -7875,8 +7876,8 @@ static u64 vmx_get_perf_capabilities(void) 
		rdmsrl(MSR_IA32_PERF_CAPABILITIES, host_perf_cap);



	if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) {

		x86_perf_get_lbr(&lbr);

		if (lbr.nr)

		x86_perf_get_lbr(&vmx_lbr_caps);

		if (vmx_lbr_caps.nr)

			perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;

	}

arch/x86/kvm/vmx/vmx.h

+2 −0
Original line number Diff line number Diff line
@@ -110,6 +110,8 @@ struct lbr_desc { 
	bool msr_passthrough;

};



extern struct x86_pmu_lbr vmx_lbr_caps;



/*

 * The nested_vmx structure is part of vcpu_vmx, and holds information we need

 * for correct emulation of VMX (i.e., nested VMX) on this vcpu.