[PATCH 04/26] vfio: Add struct to hold KVM assets and dedup group vs. iommufd code

Sean Christopherson
2023-09-16T00:33:25Z

Add a struct to hold the KVM assets need to manage and pass along KVM
references to VFIO devices. Providing a common struct deduplicates the
group vs. iommufd code, and will make it easier to rework the attachment
logic so that VFIO doesn't have to do a symbol lookup to retrieve the
get/put helpers from KVM.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
drivers/vfio/device_cdev.c | 9 +-------
drivers/vfio/group.c | 18 ++--------------
drivers/vfio/vfio.h | 22 +++++++++----------
drivers/vfio/vfio_main.c | 43 +++++++++++++++++++++++++++-----------
4 files changed, 45 insertions(+), 47 deletions(-)

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index e75da0a70d1f..e484d6d6400a 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -46,13 +46,6 @@ int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep)
return ret;
}

-static void vfio_df_get_kvm_safe(struct vfio_device_file *df)
-{
- spin_lock(&df->kvm_ref_lock);
- vfio_device_get_kvm_safe(df->device, df->kvm);
- spin_unlock(&df->kvm_ref_lock);
-}
-
long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
struct vfio_device_bind_iommufd __user *arg)
{
@@ -99,7 +92,7 @@ long vfio_df_ioctl_bind_iommufd(struct vfio_device_file *df,
* a reference. This reference is held until device closed.
* Save the pointer in the device for use by drivers.
*/
- vfio_df_get_kvm_safe(df);
+ vfio_device_get_kvm_safe(df->device, &df->kvm_ref);

ret = vfio_df_open(df);
if (ret)
diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 610a429c6191..756e47ff4cf0 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -157,13 +157,6 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
return ret;
}

-static void vfio_device_group_get_kvm_safe(struct vfio_device *device)
-{
- spin_lock(&device->group->kvm_ref_lock);
- vfio_device_get_kvm_safe(device, device->group->kvm);
- spin_unlock(&device->group->kvm_ref_lock);
-}
-
static int vfio_df_group_open(struct vfio_device_file *df)
{
struct vfio_device *device = df->device;
@@ -184,7 +177,7 @@ static int vfio_df_group_open(struct vfio_device_file *df)
* the pointer in the device for use by drivers.
*/
if (device->open_count == 0)
- vfio_device_group_get_kvm_safe(device);
+ vfio_device_get_kvm_safe(device, &device->group->kvm_ref);

df->iommufd = device->group->iommufd;
if (df->iommufd && vfio_device_is_noiommu(device) && device->open_count == 0) {
@@ -560,7 +553,7 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group,

refcount_set(&group->drivers, 1);
mutex_init(&group->group_lock);
- spin_lock_init(&group->kvm_ref_lock);
+ spin_lock_init(&group->kvm_ref.lock);
INIT_LIST_HEAD(&group->device_list);
mutex_init(&group->device_lock);
group->iommu_group = iommu_group;
@@ -884,13 +877,6 @@ bool vfio_group_enforced_coherent(struct vfio_group *group)
return ret;
}

-void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
-{
- spin_lock(&group->kvm_ref_lock);
- group->kvm = kvm;
- spin_unlock(&group->kvm_ref_lock);
-}
-
/**
* vfio_file_has_dev - True if the VFIO file is a handle for device
* @file: VFIO file to check
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index c26d1ad68105..a1f741365075 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -12,18 +12,23 @@
#include <linux/module.h>
#include <linux/vfio.h>

+struct kvm;
struct iommufd_ctx;
struct iommu_group;
struct vfio_container;

+struct vfio_kvm_reference {
+ struct kvm *kvm;
+ spinlock_t lock;
+};
+
struct vfio_device_file {
struct vfio_device *device;
struct vfio_group *group;

u8 access_granted;
u32 devid; /* only valid when iommufd is valid */
- spinlock_t kvm_ref_lock; /* protect kvm field */
- struct kvm *kvm;
+ struct vfio_kvm_reference kvm_ref;
struct iommufd_ctx *iommufd; /* protected by struct vfio_device_set::lock */
};

@@ -88,11 +93,10 @@ struct vfio_group {
#endif
enum vfio_group_type type;
struct mutex group_lock;
- struct kvm *kvm;
+ struct vfio_kvm_reference kvm_ref;
struct file *opened_file;
struct blocking_notifier_head notifier;
struct iommufd_ctx *iommufd;
- spinlock_t kvm_ref_lock;
unsigned int cdev_device_open_cnt;
};

@@ -108,7 +112,6 @@ void vfio_device_group_unuse_iommu(struct vfio_device *device);
void vfio_df_group_close(struct vfio_device_file *df);
struct vfio_group *vfio_group_from_file(struct file *file);
bool vfio_group_enforced_coherent(struct vfio_group *group);
-void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm);
bool vfio_device_has_container(struct vfio_device *device);
int __init vfio_group_init(void);
void vfio_group_cleanup(void);
@@ -171,10 +174,6 @@ static inline bool vfio_group_enforced_coherent(struct vfio_group *group)
return true;
}

-static inline void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
-{
-}
-
static inline bool vfio_device_has_container(struct vfio_device *device)
{
return false;
@@ -435,11 +434,12 @@ static inline void vfio_virqfd_exit(void)
#endif

#if IS_ENABLED(CONFIG_KVM)
-void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm);
+void vfio_device_get_kvm_safe(struct vfio_device *device,
+ struct vfio_kvm_reference *ref);
void vfio_device_put_kvm(struct vfio_device *device);
#else
static inline void vfio_device_get_kvm_safe(struct vfio_device *device,
- struct kvm *kvm)
+ struct vfio_kvm_reference *ref)
{
}

diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 124cc88966a7..e77e8c6aae2f 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -397,7 +397,7 @@ vfio_allocate_device_file(struct vfio_device *device)
return ERR_PTR(-ENOMEM);

df->device = device;
- spin_lock_init(&df->kvm_ref_lock);
+ spin_lock_init(&df->kvm_ref.lock);

return df;
}
@@ -1303,7 +1303,8 @@ bool vfio_file_enforced_coherent(struct file *file)
EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);

#if IS_ENABLED(CONFIG_KVM)
-void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)
+void vfio_device_get_kvm_safe(struct vfio_device *device,
+ struct vfio_kvm_reference *ref)
{
void (*pfn)(struct kvm *kvm);
bool (*fn)(struct kvm *kvm);
@@ -1311,28 +1312,33 @@ void vfio_device_get_kvm_safe(struct vfio_device *device, struct kvm *kvm)

lockdep_assert_held(&device->dev_set->lock);

- if (!kvm)
- return;
+ spin_lock(&ref->lock);
+
+ if (!ref->kvm)
+ goto out;

pfn = symbol_get(kvm_put_kvm);
if (WARN_ON(!pfn))
- return;
+ goto out;

fn = symbol_get(kvm_get_kvm_safe);
if (WARN_ON(!fn)) {
symbol_put(kvm_put_kvm);
- return;
+ goto out;
}

- ret = fn(kvm);
+ ret = fn(ref->kvm);
symbol_put(kvm_get_kvm_safe);
if (!ret) {
symbol_put(kvm_put_kvm);
- return;
+ goto out;
}

device->put_kvm = pfn;
- device->kvm = kvm;
+ device->kvm = ref->kvm;
+
+out:
+ spin_unlock(&ref->lock);
}

void vfio_device_put_kvm(struct vfio_device *device)
@@ -1353,6 +1359,21 @@ void vfio_device_put_kvm(struct vfio_device *device)
device->kvm = NULL;
}

+static void vfio_device_set_kvm(struct vfio_kvm_reference *ref,
+ struct kvm *kvm)
+{
+ spin_lock(&ref->lock);
+ ref->kvm = kvm;
+ spin_unlock(&ref->lock);
+}
+
+static void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
+{
+#if IS_ENABLED(CONFIG_VFIO_GROUP)
+ vfio_device_set_kvm(&group->kvm_ref, kvm);
+#endif
+}
+
static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm)
{
struct vfio_device_file *df = file->private_data;
@@ -1362,9 +1383,7 @@ static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm)
* be propagated to vfio_device::kvm when the file is bound to
* iommufd successfully in the vfio device cdev path.
*/
- spin_lock(&df->kvm_ref_lock);
- df->kvm = kvm;
- spin_unlock(&df->kvm_ref_lock);
+ vfio_device_set_kvm(&df->kvm_ref, kvm);
}

/**
--
2.42.0.459.ge4e396fd5e-goog