Commit 88ebc2a3 authored by Mingwei Zhang's avatar Mingwei Zhang Committed by Sean Christopherson
Browse files

KVM: nVMX: Disable PMU MSR interception as appropriate while running L2 



Merge KVM's PMU MSR interception bitmaps with those of L1, i.e. merge the
bitmaps of vmcs01 and vmcs12, e.g. so that KVM doesn't interpose on MSR
accesses unnecessarily if L1 exposes a mediated PMU (or equivalent) to L2.

Signed-off-by: default avatarMingwei Zhang <mizhang@google.com>
Co-developed-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
[sean: rewrite changelog and comment, omit MSRs that are always intercepted]
Tested-by: default avatarXudong Hao <xudong.hao@intel.com>
Tested-by: default avatarManali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-32-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent cb58327c

arch/x86/kvm/vmx/nested.c

+30 −0
Original line number Diff line number Diff line
@@ -630,6 +630,34 @@ static inline void nested_vmx_set_intercept_for_msr(struct vcpu_vmx *vmx, 
#define nested_vmx_merge_msr_bitmaps_rw(msr) \

	nested_vmx_merge_msr_bitmaps(msr, MSR_TYPE_RW)



static void nested_vmx_merge_pmu_msr_bitmaps(struct kvm_vcpu *vcpu,

					     unsigned long *msr_bitmap_l1,

					     unsigned long *msr_bitmap_l0)

{

	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

	struct vcpu_vmx *vmx = to_vmx(vcpu);

	int i;



	/*

	 * Skip the merges if the vCPU doesn't have a mediated PMU MSR, i.e. if

	 * none of the MSRs can possibly be passed through to L1.

	 */

	if (!kvm_vcpu_has_mediated_pmu(vcpu))

		return;



	for (i = 0; i < pmu->nr_arch_gp_counters; i++) {

		nested_vmx_merge_msr_bitmaps_rw(MSR_IA32_PERFCTR0 + i);

		nested_vmx_merge_msr_bitmaps_rw(MSR_IA32_PMC0 + i);

	}



	for (i = 0; i < pmu->nr_arch_fixed_counters; i++)

		nested_vmx_merge_msr_bitmaps_rw(MSR_CORE_PERF_FIXED_CTR0 + i);



	nested_vmx_merge_msr_bitmaps_rw(MSR_CORE_PERF_GLOBAL_CTRL);

	nested_vmx_merge_msr_bitmaps_read(MSR_CORE_PERF_GLOBAL_STATUS);

	nested_vmx_merge_msr_bitmaps_write(MSR_CORE_PERF_GLOBAL_OVF_CTRL);

}



/*

 * Merge L0's and L1's MSR bitmap, return false to indicate that

 * we do not use the hardware.
@@ -745,6 +773,8 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu, 
	nested_vmx_set_intercept_for_msr(vmx, msr_bitmap_l1, msr_bitmap_l0,

					 MSR_IA32_PL3_SSP, MSR_TYPE_RW);



	nested_vmx_merge_pmu_msr_bitmaps(vcpu, msr_bitmap_l1, msr_bitmap_l0);



	kvm_vcpu_unmap(vcpu, &map);



	vmx->nested.force_msr_bitmap_recalc = false;