[PATCH kernel v2] KVM: PPC: Merge powerpc's debugfs entry content into generic entry

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At the moment the generic KVM code creates an "%pid-%fd" entry per a KVM
instance; and the PPC HV KVM creates its own at "vm%pid". The Book3E KVM
creates its own entry for timings.

The problems with the PPC entries are:
1. they do not allow multiple VMs in the same process (which is extremely
rare case mostly used by syzkaller fuzzer);
2. prone to race bugs like the generic KVM code had fixed in
commit 85cd39af14f4 ("KVM: Do not leak memory for duplicate debugfs
directories").

This defines kvm_arch_create_kvm_debugfs() similar to one for vcpus.

This defines 2 hooks in kvmppc_ops for allowing specific KVM
implementations to add necessary entries. This defines handlers
for HV KVM and defines the Book3E debugfs vcpu helper as a handler.

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.

Suggested-by: Fabiano Rosas <farosas@xxxxxxxxxxxxx>
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Changes:
v2:
* handled powerpc-booke
* s/kvm/vm/ in arch hooks
---
 arch/powerpc/include/asm/kvm_host.h    |  7 +++---
 arch/powerpc/include/asm/kvm_ppc.h     |  2 ++
 arch/powerpc/kvm/timing.h              |  7 +++---
 include/linux/kvm_host.h               |  3 +++
 arch/powerpc/kvm/book3s_64_mmu_hv.c    |  2 +-
 arch/powerpc/kvm/book3s_64_mmu_radix.c |  2 +-
 arch/powerpc/kvm/book3s_hv.c           | 30 +++++++++-----------------
 arch/powerpc/kvm/e500.c                |  1 +
 arch/powerpc/kvm/e500mc.c              |  1 +
 arch/powerpc/kvm/powerpc.c             | 15 ++++++++++---
 arch/powerpc/kvm/timing.c              | 20 ++++-------------
 virt/kvm/kvm_main.c                    |  3 +++
 12 files changed, 44 insertions(+), 49 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 2bcac6da0a4b..f29b66cc2163 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -296,7 +296,6 @@ 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
@@ -672,7 +671,6 @@ 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
@@ -828,8 +826,6 @@ 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 */
 };
 
@@ -868,4 +864,7 @@ static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
 
+#define __KVM_HAVE_ARCH_VCPU_DEBUGFS
+#define __KVM_HAVE_ARCH_KVM_DEBUGFS
+
 #endif /* __POWERPC_KVM_HOST_H__ */
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 6355a6980ccf..fd841e844b90 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -316,6 +316,8 @@ struct kvmppc_ops {
 	int (*svm_off)(struct kvm *kvm);
 	int (*enable_dawr1)(struct kvm *kvm);
 	bool (*hash_v3_possible)(void);
+	void (*create_vm_debugfs)(struct kvm *kvm);
+	void (*create_vcpu_debugfs)(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;
diff --git a/arch/powerpc/kvm/timing.h b/arch/powerpc/kvm/timing.h
index feef7885ba82..36f7c201c6f1 100644
--- a/arch/powerpc/kvm/timing.h
+++ b/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);
+void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu,
+				struct dentry *debugfs_dentry);
 
 static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type)
 {
@@ -27,8 +27,7 @@ static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type)
 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) {}
+					      struct dentry *debugfs_dentry) {}
 static inline void kvmppc_set_exit_type(struct kvm_vcpu *vcpu, int type) {}
 #endif /* CONFIG_KVM_EXIT_TIMING */
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ae7735b490b4..4f22b1201a0d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1021,6 +1021,9 @@ int kvm_arch_pm_notifier(struct kvm *kvm, unsigned long state);
 #ifdef __KVM_HAVE_ARCH_VCPU_DEBUGFS
 void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry);
 #endif
+#ifdef __KVM_HAVE_ARCH_KVM_DEBUGFS
+void kvm_arch_create_vm_debugfs(struct kvm *kvm);
+#endif
 
 int kvm_arch_hardware_enable(void);
 void kvm_arch_hardware_disable(void);
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index c63e263312a4..33dae253a0ac 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/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);
 }
 
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index c5508744e14c..f4e083c20872 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -1452,7 +1452,7 @@ 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);
 }
 
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index c8f12b056968..046df9e0d462 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2771,19 +2771,14 @@ 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 void 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);
 }
 
 #else /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
-static void debugfs_vcpu_init(struct kvm_vcpu *vcpu, unsigned int id)
+static void kvmppc_arch_create_vcpu_debugfs_hv(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry)
 {
 }
 #endif /* CONFIG_KVM_BOOK3S_HV_EXIT_TIMING */
@@ -2907,8 +2902,6 @@ 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;
 }
 
@@ -5186,7 +5179,6 @@ 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);
@@ -5319,16 +5311,14 @@ 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 void kvmppc_arch_create_vm_debugfs_hv(struct kvm *kvm)
+{
 	kvmppc_mmu_debugfs_init(kvm);
 	if (radix_enabled())
 		kvmhv_radix_debugfs_init(kvm);
-
-	return 0;
 }
 
 static void kvmppc_free_vcores(struct kvm *kvm)
@@ -5342,8 +5332,6 @@ 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();
 
@@ -5996,6 +5984,8 @@ 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)
diff --git a/arch/powerpc/kvm/e500.c b/arch/powerpc/kvm/e500.c
index 7e8b69015d20..d82e70c3e0a9 100644
--- a/arch/powerpc/kvm/e500.c
+++ b/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,
 };
 
 static int __init kvmppc_e500_init(void)
diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 1c189b5aadcc..45eacd949f4b 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/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,
 };
 
 static int __init kvmppc_e500mc_init(void)
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index c248d6d8b9e3..c895521ac6e9 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -763,7 +763,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 		goto out_vcpu_uninit;
 
 	vcpu->arch.waitp = &vcpu->wait;
-	kvmppc_create_vcpu_debugfs(vcpu, vcpu->vcpu_id);
 	return 0;
 
 out_vcpu_uninit:
@@ -780,8 +779,6 @@ 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);
@@ -2505,3 +2502,15 @@ 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);
+}
+
+void kvm_arch_create_vm_debugfs(struct kvm *kvm)
+{
+	if (kvm->arch.kvm_ops->create_vm_debugfs)
+		kvm->arch.kvm_ops->create_vm_debugfs(kvm);
+}
diff --git a/arch/powerpc/kvm/timing.c b/arch/powerpc/kvm/timing.c
index ba56a5cbba97..e1c17afc714d 100644
--- a/arch/powerpc/kvm/timing.c
+++ b/arch/powerpc/kvm/timing.c
@@ -204,21 +204,9 @@ static const struct file_operations kvmppc_exit_timing_fops = {
 	.release = single_release,
 };
 
-void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
+void kvmppc_create_vcpu_debugfs(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);
 }
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b50dbe269f4b..85b2550e18e7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -954,6 +954,9 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 				    kvm->debugfs_dentry, stat_data,
 				    &stat_fops_per_vm);
 	}
+#ifdef __KVM_HAVE_ARCH_KVM_DEBUGFS
+	kvm_arch_create_vm_debugfs(kvm);
+#endif
 	return 0;
 }
 
-- 
2.30.2




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