linux-kernel - [PATCH 3/9] KVM: Allow to have arch-specific per-vm debugfs files

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Message-Id: <20210624181356.10235-4-peterx@redhat.com>
Date:   Thu, 24 Jun 2021 14:13:50 -0400
From:   Peter Xu <peterx@...hat.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>, peterx@...hat.com,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 3/9] KVM: Allow to have arch-specific per-vm debugfs files

Allow archs to create arch-specific nodes under kvm->debugfs_dentry directory
besides the stats fields.  The new interface kvm_arch_create_vm_debugfs() is
defined but not yet used.  It's called after kvm->debugfs_dentry is created, so
it can be referenced directly in kvm_arch_create_vm_debugfs().  Arch should
define their own versions when they want to create extra debugfs nodes.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 53d7d09eebd7..480baa55d93f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1009,6 +1009,7 @@ bool kvm_arch_dy_runnable(struct kvm_vcpu *vcpu);
 bool kvm_arch_dy_has_pending_interrupt(struct kvm_vcpu *vcpu);
 int kvm_arch_post_init_vm(struct kvm *kvm);
 void kvm_arch_pre_destroy_vm(struct kvm *kvm);
+int kvm_arch_create_vm_debugfs(struct kvm *kvm);
 
 #ifndef __KVM_HAVE_ARCH_VM_ALLOC
 /*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0b4f55370b18..6648743f4dcf 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -847,6 +847,7 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 	char dir_name[ITOA_MAX_LEN * 2];
 	struct kvm_stat_data *stat_data;
 	struct kvm_stats_debugfs_item *p;
+	int ret;
 
 	if (!debugfs_initialized())
 		return 0;
@@ -872,6 +873,13 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 				    kvm->debugfs_dentry, stat_data,
 				    &stat_fops_per_vm);
 	}
+
+	ret = kvm_arch_create_vm_debugfs(kvm);
+	if (ret) {
+		kvm_destroy_vm_debugfs(kvm);
+		return ret;
+	}
+
 	return 0;
 }
 
@@ -892,6 +900,17 @@ void __weak kvm_arch_pre_destroy_vm(struct kvm *kvm)
 {
 }
 
+/*
+ * Called after per-vm debugfs created.  When called kvm->debugfs_dentry should
+ * be setup already, so we can create arch-specific debugfs entries under it.
+ * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so
+ * a per-arch destroy interface is not needed.
+ */
+int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
+{
+	return 0;
+}
+
 static struct kvm *kvm_create_vm(unsigned long type)
 {
 	struct kvm *kvm = kvm_arch_alloc_vm();
-- 
2.31.1