[v2,53/54] KVM: x86/pmu/svm: Implement handlers to save and restore context

Commit Message

Mingwei Zhang May 6, 2024, 5:30 a.m. UTC

From: Sandipan Das <[e-mail]>

Implement the AMD-specific handlers to save and restore the state of
PMU-related MSRs when using passthrough PMU.

Signed-off-by: Sandipan Das <[e-mail]>
---
 arch/x86/kvm/svm/pmu.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

Patch

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index bed0acfaf34d..9629a172aa1b 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -295,6 +295,36 @@  static void amd_passthrough_pmu_msrs(struct kvm_vcpu *vcpu)
 	set_msr_interception(vcpu, svm->msrpm, MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_SET, msr_clear, msr_clear);
 }
 
+static void amd_save_pmu_context(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+
+	rdmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, pmu->global_ctrl);
+	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, 0);
+	rdmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS, pmu->global_status);
+
+	/* Clear global status bits if non-zero */
+	if (pmu->global_status)
+		wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR, pmu->global_status);
+}
+
+static void amd_restore_pmu_context(struct kvm_vcpu *vcpu)
+{
+	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+	u64 global_status;
+
+	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, 0);
+	rdmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS, global_status);
+
+	/* Clear host global_status MSR if non-zero. */
+	if (global_status)
+		wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR, global_status);
+
+	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_SET, pmu->global_status);
+
+	wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, pmu->global_ctrl);
+}
+
 struct kvm_pmu_ops amd_pmu_ops __initdata = {
 	.rdpmc_ecx_to_pmc = amd_rdpmc_ecx_to_pmc,
 	.msr_idx_to_pmc = amd_msr_idx_to_pmc,
@@ -306,6 +336,8 @@  struct kvm_pmu_ops amd_pmu_ops __initdata = {
 	.init = amd_pmu_init,
 	.is_rdpmc_passthru_allowed = amd_is_rdpmc_passthru_allowed,
 	.passthrough_pmu_msrs = amd_passthrough_pmu_msrs,
+	.save_pmu_context = amd_save_pmu_context,
+	.restore_pmu_context = amd_restore_pmu_context,
 	.EVENTSEL_EVENT = AMD64_EVENTSEL_EVENT,
 	.MAX_NR_GP_COUNTERS = KVM_AMD_PMC_MAX_GENERIC,
 	.MIN_NR_GP_COUNTERS = AMD64_NUM_COUNTERS,