[PATCH v7 06/22] kvm/vfio: Accept vfio device file from userspace

Yi Liu
2023-03-16T12:56:00Z

This defines KVM_DEV_VFIO_FILE* and make alias with KVM_DEV_VFIO_GROUP*.
Old userspace uses KVM_DEV_VFIO_GROUP* works as well.

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>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
Documentation/virt/kvm/devices/vfio.rst | 52 +++++++++++++++++--------
include/uapi/linux/kvm.h | 16 ++++++--
virt/kvm/vfio.c | 16 ++++----
3 files changed, 55 insertions(+), 29 deletions(-)

diff --git a/Documentation/virt/kvm/devices/vfio.rst b/Documentation/virt/kvm/devices/vfio.rst
index 79b6811bb4f3..5b05b48abaab 100644
--- a/Documentation/virt/kvm/devices/vfio.rst
+++ b/Documentation/virt/kvm/devices/vfio.rst
@@ -9,24 +9,37 @@ Device types supported:
- KVM_DEV_TYPE_VFIO

Only one VFIO instance may be created per VM. The created device
-tracks VFIO groups in use by the VM and features of those groups
-important to the correctness and acceleration of the VM. As groups
-are enabled and disabled for use by the VM, KVM should be updated
-about their presence. When registered with KVM, a reference to the
-VFIO-group is held by KVM.
+tracks VFIO files (group or device) in use by the VM and features
+of those groups/devices important to the correctness and acceleration
+of the VM. As groups/devices are enabled and disabled for use by the
+VM, KVM should be updated about their presence. When registered with
+KVM, a reference to the VFIO file is held by KVM.

Groups:
- KVM_DEV_VFIO_GROUP
-
-KVM_DEV_VFIO_GROUP attributes:
- KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking
- kvm_device_attr.addr points to an int32_t file descriptor
- for the VFIO group.
- KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking
- kvm_device_attr.addr points to an int32_t file descriptor
- for the VFIO group.
- KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
+ KVM_DEV_VFIO_FILE
+ alias: KVM_DEV_VFIO_GROUP
+
+KVM_DEV_VFIO_FILE attributes:
+ KVM_DEV_VFIO_FILE_ADD: Add a VFIO file (group/device) to VFIO-KVM device
+ tracking
+
+ alias: KVM_DEV_VFIO_GROUP_ADD
+
+ kvm_device_attr.addr points to an int32_t file descriptor for the
+ VFIO file.
+ KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from VFIO-KVM
+ device tracking
+
+ alias: KVM_DEV_VFIO_GROUP_DEL
+
+ kvm_device_attr.addr points to an int32_t file descriptor for the
+ VFIO file.
+
+ KVM_DEV_VFIO_FILE_SET_SPAPR_TCE: attaches a guest visible TCE table
allocated by sPAPR KVM.
+
+ alias: KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE
+
kvm_device_attr.addr points to a struct::

struct kvm_vfio_spapr_tce {
@@ -40,9 +53,14 @@ KVM_DEV_VFIO_GROUP attributes:
- @tablefd is a file descriptor for a TCE table allocated via
KVM_CREATE_SPAPR_TCE.

+ only accepts vfio group file as SPAPR has no iommufd support
+
::

-The GROUP_ADD operation above should be invoked prior to accessing the
+The FILE/GROUP_ADD operation above should be invoked prior to accessing the
device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support
drivers which require a kvm pointer to be set in their .open_device()
-callback.
+callback. It is the same for device file descriptor via character device
+open which gets device access via VFIO_DEVICE_BIND_IOMMUFD. For such file
+descriptors, FILE_ADD should be invoked before VFIO_DEVICE_BIND_IOMMUFD
+to support the drivers mentioned in piror sentence as well.
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index d77aef872a0a..a8eeca70a498 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1410,10 +1410,18 @@ struct kvm_device_attr {
__u64 addr; /* userspace address of attr data */
};

-#define KVM_DEV_VFIO_GROUP 1
-#define KVM_DEV_VFIO_GROUP_ADD 1
-#define KVM_DEV_VFIO_GROUP_DEL 2
-#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE 3
+#define KVM_DEV_VFIO_FILE 1
+
+#define KVM_DEV_VFIO_FILE_ADD 1
+#define KVM_DEV_VFIO_FILE_DEL 2
+#define KVM_DEV_VFIO_FILE_SET_SPAPR_TCE 3
+
+/* KVM_DEV_VFIO_GROUP aliases are for compile time uapi compatibility */
+#define KVM_DEV_VFIO_GROUP KVM_DEV_VFIO_FILE
+
+#define KVM_DEV_VFIO_GROUP_ADD KVM_DEV_VFIO_FILE_ADD
+#define KVM_DEV_VFIO_GROUP_DEL KVM_DEV_VFIO_FILE_DEL
+#define KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE KVM_DEV_VFIO_FILE_SET_SPAPR_TCE

enum kvm_device_type {
KVM_DEV_TYPE_FSL_MPIC_20 = 1,
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 857d6ba349e1..d869913baafd 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -286,18 +286,18 @@ static int kvm_vfio_set_file(struct kvm_device *dev, long attr,
int32_t fd;

switch (attr) {
- case KVM_DEV_VFIO_GROUP_ADD:
+ case KVM_DEV_VFIO_FILE_ADD:
if (get_user(fd, argp))
return -EFAULT;
return kvm_vfio_file_add(dev, fd);

- case KVM_DEV_VFIO_GROUP_DEL:
+ case KVM_DEV_VFIO_FILE_DEL:
if (get_user(fd, argp))
return -EFAULT;
return kvm_vfio_file_del(dev, fd);

#ifdef CONFIG_SPAPR_TCE_IOMMU
- case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
+ case KVM_DEV_VFIO_FILE_SET_SPAPR_TCE:
return kvm_vfio_file_set_spapr_tce(dev, arg);
#endif
}
@@ -309,7 +309,7 @@ static int kvm_vfio_set_attr(struct kvm_device *dev,
struct kvm_device_attr *attr)
{
switch (attr->group) {
- case KVM_DEV_VFIO_GROUP:
+ case KVM_DEV_VFIO_FILE:
return kvm_vfio_set_file(dev, attr->attr,
u64_to_user_ptr(attr->addr));
}
@@ -321,12 +321,12 @@ static int kvm_vfio_has_attr(struct kvm_device *dev,
struct kvm_device_attr *attr)
{
switch (attr->group) {
- case KVM_DEV_VFIO_GROUP:
+ case KVM_DEV_VFIO_FILE:
switch (attr->attr) {
- case KVM_DEV_VFIO_GROUP_ADD:
- case KVM_DEV_VFIO_GROUP_DEL:
+ case KVM_DEV_VFIO_FILE_ADD:
+ case KVM_DEV_VFIO_FILE_DEL:
#ifdef CONFIG_SPAPR_TCE_IOMMU
- case KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE:
+ case KVM_DEV_VFIO_FILE_SET_SPAPR_TCE:
#endif
return 0;
}
--
2.34.1