Currently SGX does not have a global counter to count the
active users from userspace or hypervisor. Implement such a counter,
sgx_usage_count. It will be used by the driver when attempting
to call EUPDATESVN SGX instruction.
Suggested-by: Sean Christopherson <sea...@google.com>
Signed-off-by: Elena Reshetova <elena.reshet...@intel.com>
---
arch/x86/kernel/cpu/sgx/driver.c | 22 ++++++++++++++++------
arch/x86/kernel/cpu/sgx/encl.c | 1 +
arch/x86/kernel/cpu/sgx/main.c | 14 ++++++++++++++
arch/x86/kernel/cpu/sgx/sgx.h | 3 +++
arch/x86/kernel/cpu/sgx/virt.c | 16 ++++++++++++++--
5 files changed, 48 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c
index 7f8d1e11dbee..a2994a74bdff 100644
--- a/arch/x86/kernel/cpu/sgx/driver.c
+++ b/arch/x86/kernel/cpu/sgx/driver.c
@@ -19,9 +19,15 @@ static int sgx_open(struct inode *inode, struct file *file)
struct sgx_encl *encl;
int ret;
+ ret = sgx_inc_usage_count();
+ if (ret)
+ return ret;
+
encl = kzalloc(sizeof(*encl), GFP_KERNEL);
- if (!encl)
- return -ENOMEM;
+ if (!encl) {
+ ret = -ENOMEM;
+ goto err_usage_count;
+ }
kref_init(&encl->refcount);
xa_init(&encl->page_array);
@@ -31,14 +37,18 @@ static int sgx_open(struct inode *inode, struct file *file)
spin_lock_init(&encl->mm_lock);
ret = init_srcu_struct(&encl->srcu);
- if (ret) {
- kfree(encl);
- return ret;
- }
+ if (ret)
+ goto err_encl;
file->private_data = encl;
return 0;
+
+err_encl:
+ kfree(encl);
+err_usage_count:
+ sgx_dec_usage_count();
+ return ret;
}
static int sgx_release(struct inode *inode, struct file *file)
diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 279148e72459..3b54889ae4a4 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -765,6 +765,7 @@ void sgx_encl_release(struct kref *ref)
WARN_ON_ONCE(encl->secs.epc_page);
kfree(encl);
+ sgx_dec_usage_count();
}
/*
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 2de01b379aa3..a018b01b8736 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -917,6 +917,20 @@ int sgx_set_attribute(unsigned long *allowed_attributes,
}
EXPORT_SYMBOL_GPL(sgx_set_attribute);
+/* Counter to count the active SGX users */
+static atomic64_t sgx_usage_count;
+
+int sgx_inc_usage_count(void)
+{
+ atomic64_inc(&sgx_usage_count);
+ return 0;
+}
+
+void sgx_dec_usage_count(void)
+{
+ atomic64_dec(&sgx_usage_count);
+}
+
static int __init sgx_init(void)
{
int ret;
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index d2dad21259a8..f5940393d9bd 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -102,6 +102,9 @@ static inline int __init sgx_vepc_init(void)
}
#endif
+int sgx_inc_usage_count(void);
+void sgx_dec_usage_count(void);
+
void sgx_update_lepubkeyhash(u64 *lepubkeyhash);
#endif /* _X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/sgx/virt.c b/arch/x86/kernel/cpu/sgx/virt.c
index 7aaa3652e31d..6ce908ed51c9 100644
--- a/arch/x86/kernel/cpu/sgx/virt.c
+++ b/arch/x86/kernel/cpu/sgx/virt.c
@@ -255,22 +255,34 @@ static int sgx_vepc_release(struct inode *inode, struct
file *file)
xa_destroy(&vepc->page_array);
kfree(vepc);
+ sgx_dec_usage_count();
return 0;
}
static int sgx_vepc_open(struct inode *inode, struct file *file)
{
struct sgx_vepc *vepc;
+ int ret;
+
+ ret = sgx_inc_usage_count();
+ if (ret)
+ return ret;
vepc = kzalloc(sizeof(struct sgx_vepc), GFP_KERNEL);
- if (!vepc)
- return -ENOMEM;
+ if (!vepc) {
+ ret = -ENOMEM;
+ goto err_usage_count;
+ }
mutex_init(&vepc->lock);
xa_init(&vepc->page_array);
file->private_data = vepc;
return 0;
+
+err_usage_count:
+ sgx_dec_usage_count();
+ return ret;
}
static long sgx_vepc_ioctl(struct file *file,
--
2.45.2
