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. --- drivers/vdpa/vdpa_user/vduse_dev.c | 28 ++++++++++++++++++++++++++++ include/uapi/linux/vduse.h | 7 ++++++- 2 files changed, 34 insertions(+), 1 deletion(-) diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c index 551ccde0b856..e7da69c2ad71 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. * @@ -1977,6 +1980,19 @@ static bool vduse_validate_config(struct vduse_dev_config *config, sizeof(config->reserved))) return false; + if (api_version < VDUSE_API_VERSION_2) { + if (config->vduse_features) { + dev_dbg(vduse_ctrl_dev, + "config->vduse_features with version %llu", + api_version); + return false; + } + } else { + if (config->vduse_features & ~vduse_features) + return false; + } + + if (api_version < VDUSE_API_VERSION_1 && (config->ngroups || config->nas)) return false; @@ -2237,6 +2253,18 @@ static long vduse_ioctl(struct file *file, unsigned int cmd, ret = vduse_destroy_dev(name); break; } + case VDUSE_GET_FEATURES: + if (control->api_version < VDUSE_API_VERSION_2) { + dev_dbg(vduse_ctrl_dev, + "VDUSE_GET_FEATURES ioctl with version %llu", + control->api_version); + ret = -ENOIOCTLCMD; + break; + } + + 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 dea89ed281a7..1f68e556cbf2 100644 --- a/include/uapi/linux/vduse.h +++ b/include/uapi/linux/vduse.h @@ -37,6 +37,7 @@ * @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 @@ -53,7 +54,8 @@ 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; + __u32 reserved[9]; __u32 config_size; __u8 config[]; }; @@ -67,6 +69,9 @@ 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) */ /** -- 2.52.0
