[PATCH v10 02/22] vfio: Refine vfio file kAPIs for KVM

Yi Liu
2023-04-26T15:03:42Z

This prepares for making the below kAPIs to accept both group file
and device file instead of only vfio group file.

bool vfio_file_enforced_coherent(struct file *file);
void vfio_file_set_kvm(struct file *file, struct kvm *kvm);

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Terrence Xu <terrence.xu@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/vfio/group.c | 53 +++++++++++++---------------------------
drivers/vfio/vfio.h | 3 +++
drivers/vfio/vfio_main.c | 49 +++++++++++++++++++++++++++++++++++++
include/linux/vfio.h | 1 +
virt/kvm/vfio.c | 10 ++++----
5 files changed, 75 insertions(+), 41 deletions(-)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index af2ef8006e1d..d5e9cf422d2a 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -754,6 +754,15 @@ bool vfio_device_has_container(struct vfio_device *device)
return device->group->container;
}

+struct vfio_group *vfio_group_from_file(struct file *file)
+{
+ struct vfio_group *group = file->private_data;
+
+ if (file->f_op != &vfio_group_fops)
+ return NULL;
+ return group;
+}
+
/**
* vfio_file_iommu_group - Return the struct iommu_group for the vfio group file
* @file: VFIO group file
@@ -764,13 +773,13 @@ bool vfio_device_has_container(struct vfio_device *device)
*/
struct iommu_group *vfio_file_iommu_group(struct file *file)
{
- struct vfio_group *group = file->private_data;
+ struct vfio_group *group = vfio_group_from_file(file);
struct iommu_group *iommu_group = NULL;

if (!IS_ENABLED(CONFIG_SPAPR_TCE_IOMMU))
return NULL;

- if (!vfio_file_is_group(file))
+ if (!group)
return NULL;

mutex_lock(&group->group_lock);
@@ -784,33 +793,20 @@ struct iommu_group *vfio_file_iommu_group(struct file *file)
EXPORT_SYMBOL_GPL(vfio_file_iommu_group);

/**
- * vfio_file_is_group - True if the file is usable with VFIO aPIS
+ * vfio_file_is_group - True if the file is a vfio group file
* @file: VFIO group file
*/
bool vfio_file_is_group(struct file *file)
{
- return file->f_op == &vfio_group_fops;
+ return vfio_group_from_file(file);
}
EXPORT_SYMBOL_GPL(vfio_file_is_group);

-/**
- * vfio_file_enforced_coherent - True if the DMA associated with the VFIO file
- * is always CPU cache coherent
- * @file: VFIO group file
- *
- * Enforced coherency means that the IOMMU ignores things like the PCIe no-snoop
- * bit in DMA transactions. A return of false indicates that the user has
- * rights to access additional instructions such as wbinvd on x86.
- */
-bool vfio_file_enforced_coherent(struct file *file)
+bool vfio_group_enforced_coherent(struct vfio_group *group)
{
- struct vfio_group *group = file->private_data;
struct vfio_device *device;
bool ret = true;

- if (!vfio_file_is_group(file))
- return true;
-
/*
* If the device does not have IOMMU_CAP_ENFORCE_CACHE_COHERENCY then
* any domain later attached to it will also not support it. If the cap
@@ -828,28 +824,13 @@ bool vfio_file_enforced_coherent(struct file *file)
mutex_unlock(&group->device_lock);
return ret;
}
-EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);

-/**
- * vfio_file_set_kvm - Link a kvm with VFIO drivers
- * @file: VFIO group file
- * @kvm: KVM to link
- *
- * When a VFIO device is first opened the KVM will be available in
- * device->kvm if one was associated with the group.
- */
-void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
+void vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
{
- struct vfio_group *group = file->private_data;
-
- if (!vfio_file_is_group(file))
- return;
-
spin_lock(&group->kvm_ref_lock);
group->kvm = kvm;
spin_unlock(&group->kvm_ref_lock);
}
-EXPORT_SYMBOL_GPL(vfio_file_set_kvm);

/**
* vfio_file_has_dev - True if the VFIO file is a handle for device
@@ -860,9 +841,9 @@ EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
*/
bool vfio_file_has_dev(struct file *file, struct vfio_device *device)
{
- struct vfio_group *group = file->private_data;
+ struct vfio_group *group = vfio_group_from_file(file);

- if (!vfio_file_is_group(file))
+ if (!group)
return false;

return group == device->group;
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 40a4dc9b17ff..c4b2f49c06a0 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -90,6 +90,9 @@ void vfio_device_group_unregister(struct vfio_device *device);
int vfio_device_group_use_iommu(struct vfio_device *device);
void vfio_device_group_unuse_iommu(struct vfio_device *device);
void vfio_device_group_close(struct vfio_device *device);
+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);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index c31a69b9a8bd..f036afc54b57 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1179,6 +1179,55 @@ const struct file_operations vfio_device_fops = {
.mmap = vfio_device_fops_mmap,
};

+/**
+ * vfio_file_is_valid - True if the file is valid vfio file
+ * @file: VFIO group file or VFIO device file
+ */
+bool vfio_file_is_valid(struct file *file)
+{
+ return vfio_group_from_file(file);
+}
+EXPORT_SYMBOL_GPL(vfio_file_is_valid);
+
+/**
+ * vfio_file_enforced_coherent - True if the DMA associated with the VFIO file
+ * is always CPU cache coherent
+ * @file: VFIO group file or VFIO device file
+ *
+ * Enforced coherency means that the IOMMU ignores things like the PCIe no-snoop
+ * bit in DMA transactions. A return of false indicates that the user has
+ * rights to access additional instructions such as wbinvd on x86.
+ */
+bool vfio_file_enforced_coherent(struct file *file)
+{
+ struct vfio_group *group;
+
+ group = vfio_group_from_file(file);
+ if (group)
+ return vfio_group_enforced_coherent(group);
+
+ return true;
+}
+EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
+
+/**
+ * vfio_file_set_kvm - Link a kvm with VFIO drivers
+ * @file: VFIO group file or VFIO device file
+ * @kvm: KVM to link
+ *
+ * When a VFIO device is first opened the KVM will be available in
+ * device->kvm if one was associated with the file.
+ */
+void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
+{
+ struct vfio_group *group;
+
+ group = vfio_group_from_file(file);
+ if (group)
+ vfio_group_set_kvm(group, kvm);
+}
+EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
+
/*
* Sub-module support
*/
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index cead7aebd527..3de2923b6e22 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -272,6 +272,7 @@ int vfio_mig_get_next_state(struct vfio_device *device,
*/
struct iommu_group *vfio_file_iommu_group(struct file *file);
bool vfio_file_is_group(struct file *file);
+bool vfio_file_is_valid(struct file *file);
bool vfio_file_enforced_coherent(struct file *file);
void vfio_file_set_kvm(struct file *file, struct kvm *kvm);
bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 9584eb57e0ed..b33c7b8488b3 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -64,18 +64,18 @@ static bool kvm_vfio_file_enforced_coherent(struct file *file)
return ret;
}

-static bool kvm_vfio_file_is_group(struct file *file)
+static bool kvm_vfio_file_is_valid(struct file *file)
{
bool (*fn)(struct file *file);
bool ret;

- fn = symbol_get(vfio_file_is_group);
+ fn = symbol_get(vfio_file_is_valid);
if (!fn)
return false;

ret = fn(file);

- symbol_put(vfio_file_is_group);
+ symbol_put(vfio_file_is_valid);

return ret;
}
@@ -154,8 +154,8 @@ static int kvm_vfio_group_add(struct kvm_device *dev, unsigned int fd)
if (!filp)
return -EBADF;

- /* Ensure the FD is a vfio group FD.*/
- if (!kvm_vfio_file_is_group(filp)) {
+ /* Ensure the FD is a vfio FD. */
+ if (!kvm_vfio_file_is_valid(filp)) {
ret = -EINVAL;
goto err_fput;
}
--
2.34.1