KVM: PPC: Merge powerpc's debugfs entry content into generic entry

At the moment KVM on PPC creates 4 types of entries under the kvm debugfs:
1) "%pid-%fd" per a KVM instance (for all platforms);
2) "vm%pid" (for PPC Book3s HV KVM);
3) "vm%u_vcpu%u_timing" (for PPC Book3e KVM);
4) "kvm-xive-%p" (for XIVE PPC Book3s KVM, the same for XICS);

The problem with this is that multiple VMs per process is not allowed for
2) and 3) which makes it possible for userspace to trigger errors when
creating duplicated debugfs entries.

This merges all these into 1).

This defines kvm_arch_create_kvm_debugfs() similar to
kvm_arch_create_vcpu_debugfs().

This defines 2 hooks in kvmppc_ops that allow specific KVM implementations
add necessary entries, this adds the _e500 suffix to
kvmppc_create_vcpu_debugfs_e500() to make it clear what platform it is for.

This makes use of already existing kvm_arch_create_vcpu_debugfs() on PPC.

This removes no more used debugfs_dir pointers from PPC kvm_arch structs.

This stops removing vcpu entries as once created vcpus stay around
for the entire life of a VM and removed when the KVM instance is closed,
see commit d56f5136 ("KVM: let kvm_destroy_vm_debugfs clean up vCPU
debugfs directories").
Suggested-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220111005404.162219-1-aik@ozlabs.ru

arch/powerpc/include/asm/kvm_host.h

@@ -26,6 +26,8 @@
 #include <asm/hvcall.h>
 #include <asm/mce.h>
 
+#define __KVM_HAVE_ARCH_VCPU_DEBUGFS
+
 #define KVM_MAX_VCPUS		NR_CPUS
 #define KVM_MAX_VCORES		NR_CPUS
 
@@ -295,7 +297,6 @@ struct kvm_arch {
 	bool dawr1_enabled;
 	pgd_t *pgtable;
 	u64 process_table;
-	struct dentry *debugfs_dir;
 	struct kvm_resize_hpt *resize_hpt; /* protected by kvm->lock */
 #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
 #ifdef CONFIG_KVM_BOOK3S_PR_POSSIBLE
@@ -673,7 +674,6 @@ struct kvm_vcpu_arch {
 	u64 timing_min_duration[__NUMBER_OF_KVM_EXIT_TYPES];
 	u64 timing_max_duration[__NUMBER_OF_KVM_EXIT_TYPES];
 	u64 timing_last_exit;
-	struct dentry *debugfs_exit_timing;
 #endif
 
 #ifdef CONFIG_PPC_BOOK3S
@@ -831,8 +831,6 @@ struct kvm_vcpu_arch {
 	struct kvmhv_tb_accumulator rm_exit;	/* real-mode exit code */
 	struct kvmhv_tb_accumulator guest_time;	/* guest execution */
 	struct kvmhv_tb_accumulator cede_time;	/* time napping inside guest */
-
-	struct dentry *debugfs_dir;
 #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
 };
 

arch/powerpc/include/asm/kvm_ppc.h

@@ -314,6 +314,8 @@ struct kvmppc_ops {
 	int (*svm_off)(struct kvm *kvm);
 	int (*enable_dawr1)(struct kvm *kvm);
 	bool (*hash_v3_possible)(void);
+	int (*create_vm_debugfs)(struct kvm *kvm);
+	int (*create_vcpu_debugfs)(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;

arch/powerpc/kvm/book3s_64_mmu_hv.c

@@ -2112,7 +2112,7 @@ static const struct file_operations debugfs_htab_fops = {
 
 void kvmppc_mmu_debugfs_init(struct kvm *kvm)
 {
-	debugfs_create_file("htab", 0400, kvm->arch.debugfs_dir, kvm,
+	debugfs_create_file("htab", 0400, kvm->debugfs_dentry, kvm,
 			    &debugfs_htab_fops);
 }
 

arch/powerpc/kvm/book3s_64_mmu_radix.c

@@ -1454,7 +1454,7 @@ static const struct file_operations debugfs_radix_fops = {
 
 void kvmhv_radix_debugfs_init(struct kvm *kvm)
 {
-	debugfs_create_file("radix", 0400, kvm->arch.debugfs_dir, kvm,
+	debugfs_create_file("radix", 0400, kvm->debugfs_dentry, kvm,
 			    &debugfs_radix_fops);
 }
 

arch/powerpc/kvm/book3s_hv.c

@@ -2767,20 +2767,17 @@ static const struct file_operations debugfs_timings_ops = {
 };
 
 /* Create a debugfs directory for the vcpu */
-static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id)
+static int kvmppc_arch_create_vcpu_debugfs_hv(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
 {
-	char buf[16];
-	struct kvm *kvm = vcpu->kvm;
-
-	snprintf(buf, sizeof(buf), "vcpu%u", id);
-	vcpu->arch.debugfs_dir = debugfs_create_dir(buf, kvm->arch.debugfs_dir);
-	debugfs_create_file("timings", 0444, vcpu->arch.debugfs_dir, vcpu,
+	debugfs_create_file("timings", 0444, debugfs_dentry, vcpu,
 			    &debugfs_timings_ops);
+	return 0;
 }
 
 #else /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
-static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id)
+static int kvmppc_arch_create_vcpu_debugfs_hv(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
 {
+	return 0;
 }
 #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
 
@@ -2903,8 +2900,6 @@ static int kvmppc_core_vcpu_create_hv(struct kvm_vcpu *vcpu)
 	vcpu->arch.cpu_type = KVM_CPU_3S_64;
 	kvmppc_sanity_check(vcpu);
 
-	debugfs_vcpu_init(vcpu, id);
-
 	return 0;
 }
 
@@ -5223,7 +5218,6 @@ void kvmppc_free_host_rm_ops(void)
 static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 {
 	unsigned long lpcr, lpid;
-	char buf[32];
 	int ret;
 
 	mutex_init(&kvm->arch.uvmem_lock);
@@ -5356,15 +5350,14 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
 		kvm->arch.smt_mode = 1;
 	kvm->arch.emul_smt_mode = 1;
 
-	/*
-	 * Create a debugfs directory for the VM
-	 */
-	snprintf(buf, sizeof(buf), "vm%d", current->pid);
-	kvm->arch.debugfs_dir = debugfs_create_dir(buf, kvm_debugfs_dir);
+	return 0;
+}
+
+static int kvmppc_arch_create_vm_debugfs_hv(struct kvm *kvm)
+{
 	kvmppc_mmu_debugfs_init(kvm);
 	if (radix_enabled())
 		kvmhv_radix_debugfs_init(kvm);
-
 	return 0;
 }
 
@@ -5379,8 +5372,6 @@ static void kvmppc_free_vcores(struct kvm *kvm)
 
 static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
 {
-	debugfs_remove_recursive(kvm->arch.debugfs_dir);
-
 	if (!cpu_has_feature(CPU_FTR_ARCH_300))
 		kvm_hv_vm_deactivated();
 
@@ -6042,6 +6033,8 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.svm_off = kvmhv_svm_off,
 	.enable_dawr1 = kvmhv_enable_dawr1,
 	.hash_v3_possible = kvmppc_hash_v3_possible,
+	.create_vcpu_debugfs = kvmppc_arch_create_vcpu_debugfs_hv,
+	.create_vm_debugfs = kvmppc_arch_create_vm_debugfs_hv,
 };
 
 static int kvm_init_subcore_bitmap(void)

arch/powerpc/kvm/book3s_xics.c

@@ -1016,19 +1016,10 @@ DEFINE_SHOW_ATTRIBUTE(xics_debug);
 
 static void xics_debugfs_init(struct kvmppc_xics *xics)
 {
-	char *name;
-
-	name = kasprintf(GFP_KERNEL, "kvm-xics-%p", xics);
-	if (!name) {
-		pr_err("%s: no memory for name\n", __func__);
-		return;
-	}
-
-	xics->dentry = debugfs_create_file(name, 0444, arch_debugfs_dir,
+	xics->dentry = debugfs_create_file("xics", 0444, xics->kvm->debugfs_dentry,
 					   xics, &xics_debug_fops);
 
-	pr_debug("%s: created %s\n", __func__, name);
-	kfree(name);
+	pr_debug("%s: created\n", __func__);
 }
 
 static struct kvmppc_ics *kvmppc_xics_create_ics(struct kvm *kvm,

arch/powerpc/kvm/book3s_xive.c

@@ -2354,19 +2354,10 @@ DEFINE_SHOW_ATTRIBUTE(xive_debug);
 
 static void xive_debugfs_init(struct kvmppc_xive *xive)
 {
-	char *name;
-
-	name = kasprintf(GFP_KERNEL, "kvm-xive-%p", xive);
-	if (!name) {
-		pr_err("%s: no memory for name\n", __func__);
-		return;
-	}
-
-	xive->dentry = debugfs_create_file(name, S_IRUGO, arch_debugfs_dir,
+	xive->dentry = debugfs_create_file("xive", S_IRUGO, xive->kvm->debugfs_dentry,
 					   xive, &xive_debug_fops);
 
-	pr_debug("%s: created %s\n", __func__, name);
-	kfree(name);
+	pr_debug("%s: created\n", __func__);
 }
 
 static void kvmppc_xive_init(struct kvm_device *dev)

arch/powerpc/kvm/book3s_xive_native.c

@@ -1259,19 +1259,10 @@ DEFINE_SHOW_ATTRIBUTE(xive_native_debug);
 
 static void xive_native_debugfs_init(struct kvmppc_xive *xive)
 {
-	char *name;
-
-	name = kasprintf(GFP_KERNEL, "kvm-xive-%p", xive);
-	if (!name) {
-		pr_err("%s: no memory for name\n", __func__);
-		return;
-	}
-
-	xive->dentry = debugfs_create_file(name, 0444, arch_debugfs_dir,
+	xive->dentry = debugfs_create_file("xive", 0444, xive->kvm->debugfs_dentry,
 					   xive, &xive_native_debug_fops);
 
-	pr_debug("%s: created %s\n", __func__, name);
-	kfree(name);
+	pr_debug("%s: created\n", __func__);
 }
 
 static void kvmppc_xive_native_init(struct kvm_device *dev)

arch/powerpc/kvm/e500.c

@@ -495,6 +495,7 @@ static struct kvmppc_ops kvm_ops_e500 = {
 	.emulate_op = kvmppc_core_emulate_op_e500,
 	.emulate_mtspr = kvmppc_core_emulate_mtspr_e500,
 	.emulate_mfspr = kvmppc_core_emulate_mfspr_e500,
+	.create_vcpu_debugfs = kvmppc_create_vcpu_debugfs_e500,
 };
 
 static int __init kvmppc_e500_init(void)

arch/powerpc/kvm/e500mc.c

@@ -381,6 +381,7 @@ static struct kvmppc_ops kvm_ops_e500mc = {
 	.emulate_op = kvmppc_core_emulate_op_e500,
 	.emulate_mtspr = kvmppc_core_emulate_mtspr_e500,
 	.emulate_mfspr = kvmppc_core_emulate_mfspr_e500,
+	.create_vcpu_debugfs = kvmppc_create_vcpu_debugfs_e500,
 };
 
 static int __init kvmppc_e500mc_init(void)

arch/powerpc/kvm/powerpc.c

@@ -777,7 +777,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	rcuwait_init(&vcpu->arch.wait);
 	vcpu->arch.waitp = &vcpu->arch.wait;
-	kvmppc_create_vcpu_debugfs(vcpu, vcpu->vcpu_id);
 	return 0;
 
 out_vcpu_uninit:
@@ -794,8 +793,6 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 	/* Make sure we're not using the vcpu anymore */
 	hrtimer_cancel(&vcpu->arch.dec_timer);
 
-	kvmppc_remove_vcpu_debugfs(vcpu);
-
 	switch (vcpu->arch.irq_type) {
 	case KVMPPC_IRQ_MPIC:
 		kvmppc_mpic_disconnect_vcpu(vcpu->arch.mpic, vcpu);
@@ -2521,3 +2518,16 @@ int kvm_arch_init(void *opaque)
 }
 
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_ppc_instr);
+
+void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
+{
+	if (vcpu->kvm->arch.kvm_ops->create_vcpu_debugfs)
+		vcpu->kvm->arch.kvm_ops->create_vcpu_debugfs(vcpu, debugfs_dentry);
+}
+
+int kvm_arch_create_vm_debugfs(struct kvm *kvm)
+{
+	if (kvm->arch.kvm_ops->create_vm_debugfs)
+		kvm->arch.kvm_ops->create_vm_debugfs(kvm);
+	return 0;
+}

arch/powerpc/kvm/timing.c

@@ -204,21 +204,10 @@ static const struct file_operations kvmppc_exit_timing_fops = {
 	.release = single_release,
 };
 
-void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
+int kvmppc_create_vcpu_debugfs_e500(struct kvm_vcpu *vcpu,
+				    struct dentry *debugfs_dentry)
 {
-	static char dbg_fname[50];
-	struct dentry *debugfs_file;
-
-	snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
-		 current->pid, id);
-	debugfs_file = debugfs_create_file(dbg_fname, 0666, kvm_debugfs_dir,
-						vcpu, &kvmppc_exit_timing_fops);
-
-	vcpu->arch.debugfs_exit_timing = debugfs_file;
-}
-
-void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
-{
-	debugfs_remove(vcpu->arch.debugfs_exit_timing);
-	vcpu->arch.debugfs_exit_timing = NULL;
+	debugfs_create_file("timing", 0666, debugfs_dentry,
+			    vcpu, &kvmppc_exit_timing_fops);
+	return 0;
 }

arch/powerpc/kvm/timing.h

@@ -14,8 +14,8 @@
 #ifdef CONFIG_KVM_EXIT_TIMING
 void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu);
 void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu);
-void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id);
-void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu);
+int kvmppc_create_vcpu_debugfs_e500(struct kvm_vcpu *vcpu,
+				    struct dentry *debugfs_dentry);
 
 static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type)
 {
@@ -26,9 +26,11 @@ static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type)
 /* if exit timing is not configured there is no need to build the c file */
 static inline void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu) {}
 static inline void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu) {}
-static inline void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu,
-						unsigned int id) {}
-static inline void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
+static inline int kvmppc_create_vcpu_debugfs_e500(struct kvm_vcpu *vcpu,
+						  struct dentry *debugfs_dentry)
+{
+	return 0;
+}
 static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type) {}
 #endif /* CONFIG_KVM_EXIT_TIMING */