linux-kernel - [PATCH RFC v7 4/8] KVM: Add kvm_gmem

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Message-ID: <20250408112402.181574-5-shivankg@amd.com>
Date: Tue, 8 Apr 2025 11:23:58 +0000
From: Shivank Garg <shivankg@....com>
To: <seanjc@...gle.com>, <david@...hat.com>, <vbabka@...e.cz>,
	<willy@...radead.org>, <akpm@...ux-foundation.org>, <shuah@...nel.org>,
	<pbonzini@...hat.com>
CC: <ackerleytng@...gle.com>, <paul@...l-moore.com>, <jmorris@...ei.org>,
	<serge@...lyn.com>, <pvorel@...e.cz>, <bfoster@...hat.com>,
	<tabba@...gle.com>, <vannapurve@...gle.com>, <chao.gao@...el.com>,
	<bharata@....com>, <nikunj@....com>, <michael.day@....com>,
	<yan.y.zhao@...el.com>, <Neeraj.Upadhyay@....com>, <thomas.lendacky@....com>,
	<michael.roth@....com>, <aik@....com>, <jgg@...dia.com>,
	<kalyazin@...zon.com>, <peterx@...hat.com>, <shivankg@....com>,
	<linux-fsdevel@...r.kernel.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, <linux-security-module@...r.kernel.org>,
	<kvm@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
	<linux-coco@...ts.linux.dev>
Subject: [PATCH RFC v7 4/8] KVM: Add kvm_gmem_exit() cleanup function

Add empty kvm_gmem_exit() function for proper cleanup of guest memory
resources. Call it from both kvm_init() error path and kvm_exit().

This is preparatory change for upcoming work that involves KVM guest_memfd
using inodes to store metadata for backing memory.

Signed-off-by: Shivank Garg <shivankg@....com>
---
 virt/kvm/guest_memfd.c | 5 +++++
 virt/kvm/kvm_main.c    | 2 ++
 virt/kvm/kvm_mm.h      | 6 ++++++
 3 files changed, 13 insertions(+)

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index b2aa6bf24d3a..88453b040926 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -323,6 +323,11 @@ void kvm_gmem_init(struct module *module)
 	kvm_gmem_fops.owner = module;
 }
 
+void kvm_gmem_exit(void)
+{
+
+}
+
 static int kvm_gmem_migrate_folio(struct address_space *mapping,
 				  struct folio *dst, struct folio *src,
 				  enum migrate_mode mode)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e85b33a92624..39580f79908a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -6441,6 +6441,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
 err_register:
 	kvm_uninit_virtualization();
 err_virt:
+	kvm_gmem_exit();
 	kvm_vfio_ops_exit();
 err_vfio:
 	kvm_async_pf_deinit();
@@ -6471,6 +6472,7 @@ void kvm_exit(void)
 	debugfs_remove_recursive(kvm_debugfs_dir);
 	for_each_possible_cpu(cpu)
 		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
+	kvm_gmem_exit();
 	kmem_cache_destroy(kvm_vcpu_cache);
 	kvm_vfio_ops_exit();
 	kvm_async_pf_deinit();
diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h
index acef3f5c582a..8070956b1a43 100644
--- a/virt/kvm/kvm_mm.h
+++ b/virt/kvm/kvm_mm.h
@@ -69,6 +69,7 @@ static inline void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
 
 #ifdef CONFIG_KVM_PRIVATE_MEM
 void kvm_gmem_init(struct module *module);
+void kvm_gmem_exit(void);
 int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args);
 int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
 		  unsigned int fd, loff_t offset);
@@ -79,6 +80,11 @@ static inline void kvm_gmem_init(struct module *module)
 
 }
 
+static inline void kvm_gmem_exit(void)
+{
+
+}
+
 static inline int kvm_gmem_bind(struct kvm *kvm,
 					 struct kvm_memory_slot *slot,
 					 unsigned int fd, loff_t offset)
-- 
2.34.1