Provide a helper to derive the immutable MSHV partition ID from a partition file. IOMMU drivers can use this to bind a vIOMMU to the partition object represented by a userspace fd instead of relying on current-task lookup.
Keep the public helper in built-in Hyper-V common code and let the MSHV root driver register the partition-file callbacks. This lets built-in IOMMU callers avoid symbol_get() when MSHV_ROOT is built as a module. Assisted-by: GPT-5.6 Sol Signed-off-by: Jacob Pan <[email protected]> --- drivers/hv/hv_common.c | 69 ++++++++++++++++++++++++++++++++++ drivers/hv/mshv_root_main.c | 36 +++++++++++++++++- include/asm-generic/mshyperv.h | 35 +++++++++++++++++ 3 files changed, 139 insertions(+), 1 deletion(-) diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index 31256cb22b39..d259cb833376 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -17,6 +17,7 @@ #include <linux/export.h> #include <linux/bitfield.h> #include <linux/cpumask.h> +#include <linux/fs.h> #include <linux/sched/task_stack.h> #include <linux/panic_notifier.h> #include <linux/ptrace.h> @@ -24,6 +25,7 @@ #include <linux/efi.h> #include <linux/kdebug.h> #include <linux/kmsg_dump.h> +#include <linux/mutex.h> #include <linux/sizes.h> #include <linux/slab.h> #include <linux/dma-map-ops.h> @@ -37,6 +39,73 @@ EXPORT_SYMBOL_GPL(hv_current_partition_id); enum hv_partition_type hv_curr_partition_type; EXPORT_SYMBOL_GPL(hv_curr_partition_type); +static DEFINE_MUTEX(mshv_partition_file_ops_lock); +static const struct mshv_partition_file_ops *mshv_partition_file_ops; + +int mshv_partition_file_ops_register(const struct mshv_partition_file_ops *ops) +{ + int ret = 0; + + if (!ops || !ops->file_is_partition || !ops->get_partid) + return -EINVAL; + + mutex_lock(&mshv_partition_file_ops_lock); + if (mshv_partition_file_ops) + ret = -EBUSY; + else + mshv_partition_file_ops = ops; + mutex_unlock(&mshv_partition_file_ops_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(mshv_partition_file_ops_register); + +void +mshv_partition_file_ops_unregister(const struct mshv_partition_file_ops *ops) +{ + mutex_lock(&mshv_partition_file_ops_lock); + if (mshv_partition_file_ops == ops) + mshv_partition_file_ops = NULL; + mutex_unlock(&mshv_partition_file_ops_lock); +} +EXPORT_SYMBOL_GPL(mshv_partition_file_ops_unregister); + +bool file_is_mshv_partition(struct file *file) +{ + const struct mshv_partition_file_ops *ops; + bool ret = false; + + if (!file) + return false; + + mutex_lock(&mshv_partition_file_ops_lock); + ops = mshv_partition_file_ops; + if (ops) + ret = ops->file_is_partition(file); + mutex_unlock(&mshv_partition_file_ops_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(file_is_mshv_partition); + +u64 mshv_partition_file_get_partid(struct file *file) +{ + const struct mshv_partition_file_ops *ops; + u64 ret = HV_PARTITION_ID_INVALID; + + if (!file) + return HV_PARTITION_ID_INVALID; + + mutex_lock(&mshv_partition_file_ops_lock); + ops = mshv_partition_file_ops; + if (ops && ops->file_is_partition(file)) + ret = ops->get_partid(file); + mutex_unlock(&mshv_partition_file_ops_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(mshv_partition_file_get_partid); + /* * ms_hyperv and hv_nested are defined here with other * Hyper-V specific globals so they are shared across all architectures and are diff --git a/drivers/hv/mshv_root_main.c b/drivers/hv/mshv_root_main.c index 8b31e3948c09..838ea6397c9f 100644 --- a/drivers/hv/mshv_root_main.c +++ b/drivers/hv/mshv_root_main.c @@ -2160,6 +2160,33 @@ u64 mshv_current_partid(void) } EXPORT_SYMBOL_GPL(mshv_current_partid); +static bool mshv_partition_file_is_valid(struct file *file) +{ + if (!file) + return false; + + if (file->f_op == &mshv_partition_fops) + return true; + + return false; +} + +static u64 mshv_partition_file_get_partid_impl(struct file *file) +{ + if (file->f_op == &mshv_partition_fops) { + struct mshv_partition *partition = file->private_data; + + return partition ? partition->pt_id : HV_PARTITION_ID_INVALID; + } + + return HV_PARTITION_ID_INVALID; +} + +static const struct mshv_partition_file_ops mshv_partition_file_ops = { + .file_is_partition = mshv_partition_file_is_valid, + .get_partid = mshv_partition_file_get_partid_impl, +}; + static int add_partition(struct mshv_partition *partition) { @@ -2599,10 +2626,14 @@ static int __init mshv_parent_partition_init(void) if (hv_get_hypervisor_version(&version_info)) return -ENODEV; - ret = misc_register(&mshv_dev); + ret = mshv_partition_file_ops_register(&mshv_partition_file_ops); if (ret) return ret; + ret = misc_register(&mshv_dev); + if (ret) + goto unregister_file_ops; + dev = mshv_dev.this_device; if (version_info.build_number < MSHV_HV_MIN_VERSION || @@ -2652,6 +2683,8 @@ static int __init mshv_parent_partition_init(void) mshv_synic_exit(); device_deregister: misc_deregister(&mshv_dev); +unregister_file_ops: + mshv_partition_file_ops_unregister(&mshv_partition_file_ops); return ret; } @@ -2661,6 +2694,7 @@ static void __exit mshv_parent_partition_exit(void) mshv_port_table_fini(); mshv_debugfs_exit(); misc_deregister(&mshv_dev); + mshv_partition_file_ops_unregister(&mshv_partition_file_ops); mshv_irqfd_wq_cleanup(); root_scheduler_deinit(); mshv_synic_exit(); diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index c7258cd72a89..ed7ab21d68a2 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -401,6 +401,41 @@ static inline u64 mshv_current_partid(void) } #endif /* CONFIG_MSHV_ROOT */ +struct file; +struct mshv_partition_file_ops { + bool (*file_is_partition)(struct file *file); + u64 (*get_partid)(struct file *file); +}; + +#if IS_ENABLED(CONFIG_HYPERV) +int mshv_partition_file_ops_register(const struct mshv_partition_file_ops *ops); +void +mshv_partition_file_ops_unregister(const struct mshv_partition_file_ops *ops); +bool file_is_mshv_partition(struct file *file); +u64 mshv_partition_file_get_partid(struct file *file); +#else +static inline int +mshv_partition_file_ops_register(const struct mshv_partition_file_ops *ops) +{ + return -EOPNOTSUPP; +} + +static inline void +mshv_partition_file_ops_unregister(const struct mshv_partition_file_ops *ops) +{ +} + +static inline bool file_is_mshv_partition(struct file *file) +{ + return false; +} + +static inline u64 mshv_partition_file_get_partid(struct file *file) +{ + return HV_PARTITION_ID_INVALID; +} +#endif + static inline int hv_deposit_memory(u64 partition_id, u64 status) { return hv_deposit_memory_node(NUMA_NO_NODE, partition_id, status); -- 2.43.0
