[Intel-gfx] [PATCH v9 06/25] kvm/vfio: Accept vfio device file from userspace
Eric Auger
eric.auger at redhat.com
Thu Apr 6 09:46:55 UTC 2023
Hi Yi,
On 4/1/23 17:18, Yi Liu wrote:
> 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 at nvidia.com>
> Reviewed-by: Kevin Tian <kevin.tian at intel.com>
> Tested-by: Terrence Xu <terrence.xu at intel.com>
> Tested-by: Nicolin Chen <nicolinc at nvidia.com>
> Tested-by: Matthew Rosato <mjrosato at linux.ibm.com>
> Tested-by: Yanting Jiang <yanting.jiang at intel.com>
> Signed-off-by: Yi Liu <yi.l.liu at intel.com>
> ---
> Documentation/virt/kvm/devices/vfio.rst | 53 +++++++++++++++++--------
> include/uapi/linux/kvm.h | 16 ++++++--
> virt/kvm/vfio.c | 16 ++++----
> 3 files changed, 56 insertions(+), 29 deletions(-)
>
> diff --git a/Documentation/virt/kvm/devices/vfio.rst b/Documentation/virt/kvm/devices/vfio.rst
> index 79b6811bb4f3..277d727ec1a2 100644
> --- a/Documentation/virt/kvm/devices/vfio.rst
> +++ b/Documentation/virt/kvm/devices/vfio.rst
> @@ -9,24 +9,38 @@ 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 +54,14 @@ 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
So then what is the point of introducing
KVM_DEV_VFIO_FILE_SET_SPAPR_TCE at this stage?
I think would have separated the
Groups:
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
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
kvm_device_attr.addr points to an int32_t file descriptor for the
VFIO file.
KVM_DEV_VFIO_GROUP (legacy kvm device group restricted to the handling of VFIO group fd)
KVM_DEV_VFIO_GROUP_ADD: same as KVM_DEV_VFIO_FILE_ADD for group fd only
KVM_DEV_VFIO_GROUP_DEL: same as KVM_DEV_VFIO_FILE_DEL for group fd only
KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table
allocated by sPAPR KVM.
kvm_device_attr.addr points to a struct::
struct kvm_vfio_spapr_tce {
__s32 groupfd;
__s32 tablefd;
};
where:
- @groupfd is a file descriptor for a VFIO group;
- @tablefd is a file descriptor for a TCE table allocated via
KVM_CREATE_SPAPR_TCE.
You don't say anything about potential restriction, ie. what if the user calls KVM_DEV_VFIO_FILE with device fds while it has been using legacy container/group API?
Thanks
Eric
> +
> ::
>
> -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 prior 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;
> }
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