Add an ioctl to allow VDUSE instances to query the available features supported by the kernel module.
Signed-off-by: Eugenio Pérez <[email protected]> --- A simple u64 bitmap is used for feature flags. While a flexible array could support indefinite expansion, 64 bits is sufficient for the foreseeable future and simplifies the implementation. Also, dev_dbg is used for logging rather than dev_err as these can be triggered from userspace. --- v3: * Remove check for API_VERSION < 2 * Add comment about struct vduse_dev_config:vduse_features is only valid if VDUSE_GET_FEATURES success. v2: * return -EINVAL if ioctl called with version < 2, so userland visible reply is kept (Jason). --- drivers/vdpa/vdpa_user/vduse_dev.c | 7 +++++++ include/uapi/linux/vduse.h | 7 ++++++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c index d1da7c15d98b..17e0358d3a68 100644 --- a/drivers/vdpa/vdpa_user/vduse_dev.c +++ b/drivers/vdpa/vdpa_user/vduse_dev.c @@ -52,6 +52,9 @@ #define IRQ_UNBOUND -1 +/* Supported VDUSE features */ +static const uint64_t vduse_features; + /* * VDUSE instance have not asked the vduse API version, so assume 0. * @@ -2207,6 +2210,10 @@ static long vduse_ioctl(struct file *file, unsigned int cmd, ret = vduse_destroy_dev(name); break; } + case VDUSE_GET_FEATURES: + ret = put_user(vduse_features, (u64 __user *)argp); + break; + default: ret = -EINVAL; break; diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h index 361eea511c21..e9b5f32a452d 100644 --- a/include/uapi/linux/vduse.h +++ b/include/uapi/linux/vduse.h @@ -33,6 +33,7 @@ * @vq_align: the allocation alignment of virtqueue's metadata * @ngroups: number of vq groups that VDUSE device declares * @nas: number of address spaces that VDUSE device declares + * @vduse_features: VDUSE features * @reserved: for future use, needs to be initialized to zero * @config_size: the size of the configuration space * @config: the buffer of the configuration space @@ -49,7 +50,8 @@ struct vduse_dev_config { __u32 vq_align; __u32 ngroups; /* if VDUSE_API_VERSION >= 1 */ __u32 nas; /* if VDUSE_API_VERSION >= 1 */ - __u32 reserved[11]; + __u64 vduse_features; /* if VDUSE_GET_FEATURES is not EINVAL */ + __u32 reserved[9]; __u32 config_size; __u8 config[]; }; @@ -63,6 +65,9 @@ struct vduse_dev_config { */ #define VDUSE_DESTROY_DEV _IOW(VDUSE_BASE, 0x03, char[VDUSE_NAME_MAX]) +/* Get the VDUSE supported features */ +#define VDUSE_GET_FEATURES _IOR(VDUSE_BASE, 0x04, __u64) + /* The ioctls for VDUSE device (/dev/vduse/$NAME) */ /** -- 2.53.0
