[PATCH 2/4] KVM: arm64: Keep a list of probed PMUs

[Alexandru Elisei <alexandru.elisei@arm.com>]

The ARM PMU driver calls kvm_host_pmu_init() after probing to tell KVM that
a hardware PMU is available for guest emulation. Heterogeneous systems can
have more than one PMU present, and the callback gets called multiple
times, once for each of them. Keep track of all the PMUs available to KVM,
as we're going to need them later.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arch/arm64/kvm/pmu-emul.c | 26 ++++++++++++++++++++++++--
 include/kvm/arm_pmu.h     |  5 +++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a5e4bbf5e68f..dab335d17409 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -7,6 +7,7 @@
 #include <linux/cpu.h>
 #include <linux/kvm.h>
 #include <linux/kvm_host.h>
+#include <linux/list.h>
 #include <linux/perf_event.h>
 #include <linux/perf/arm_pmu.h>
 #include <linux/uaccess.h>
@@ -14,6 +15,9 @@
 #include <kvm/arm_pmu.h>
 #include <kvm/arm_vgic.h>
 
+static LIST_HEAD(arm_pmus);
+static DEFINE_MUTEX(arm_pmus_lock);
+
 static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc);
@@ -742,9 +746,27 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
 
 void kvm_host_pmu_init(struct arm_pmu *pmu)
 {
-	if (pmu->pmuver != 0 && pmu->pmuver != ID_AA64DFR0_PMUVER_IMP_DEF &&
-	    !kvm_arm_support_pmu_v3() && !is_protected_kvm_enabled())
+	struct arm_pmu_entry *entry;
+
+	if (pmu->pmuver == 0 || pmu->pmuver == ID_AA64DFR0_PMUVER_IMP_DEF ||
+	    is_protected_kvm_enabled())
+		return;
+
+	/* Protect list changes against asynchronous driver probing. */
+	mutex_lock(&arm_pmus_lock);
+
+	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		goto out_unlock;
+
+	if (list_empty(&arm_pmus))
 		static_branch_enable(&kvm_arm_pmu_available);
+
+	entry->arm_pmu = pmu;
+	list_add_tail(&entry->entry, &arm_pmus);
+
+out_unlock:
+	mutex_unlock(&arm_pmus_lock);
 }
 
 static int kvm_pmu_probe_pmuver(void)
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 90f21898aad8..e249c5f172aa 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -36,6 +36,11 @@ struct kvm_pmu {
 	struct irq_work overflow_work;
 };
 
+struct arm_pmu_entry {
+	struct list_head entry;
+	struct arm_pmu *arm_pmu;
+};
+
 #define kvm_arm_pmu_irq_initialized(v)	((v)->arch.pmu.irq_num >= VGIC_NR_SGIS)
 u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
-- 
2.33.1

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