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To make sure mappings do not change during preserved state, add a liveupdate_immutable flag to IOAS. When an HWPT is preserved, its IOAS is marked immutable and any map/unmap attempts will fail with -EBUSY. This is synchronized using the domains_rwsem to prevent races with concurrent mapping operations. The preserve callback iterates over the marked HWPTs, verifies that the backing memory pages are preserved, and calls iommu_domain_preserve() to preserve the associated IOMMU domain. Signed-off-by: YiFei Zhu Signed-off-by: Samiullah Khawaja --- MAINTAINERS | 1 + drivers/iommu/iommufd/io_pagetable.c | 11 + drivers/iommu/iommufd/io_pagetable.h | 1 + drivers/iommu/iommufd/iommufd_private.h | 27 ++- drivers/iommu/iommufd/liveupdate.c | 287 ++++++++++++++++++++++++ drivers/iommu/iommufd/main.c | 10 +- drivers/iommu/iommufd/pages.c | 7 + include/linux/kho/abi/iommufd.h | 51 +++++ 8 files changed, 393 insertions(+), 2 deletions(-) create mode 100644 include/linux/kho/abi/iommufd.h diff --git a/MAINTAINERS b/MAINTAINERS index bf6a2ad61989..6005b737d1c5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13500,6 +13500,7 @@ F: drivers/iommu/iommufd/liveupdate.c F: drivers/iommu/liveupdate.c F: include/linux/iommu-liveupdate.h F: include/linux/kho/abi/iommu.h +F: include/linux/kho/abi/iommufd.h IOMMUFD M: Jason Gunthorpe diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index 24d4917105d9..b18dba9dd147 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -384,6 +384,11 @@ int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list, return rc; down_read(&iopt->domains_rwsem); + if (iopt_liveupdate_immutable(iopt)) { + rc = -EBUSY; + goto out_unlock_domains; + } + rc = iopt_fill_domains_pages(pages_list); if (rc) goto out_unlock_domains; @@ -755,6 +760,12 @@ static int iopt_unmap_iova_range(struct io_pagetable *iopt, unsigned long start, again: down_read(&iopt->domains_rwsem); down_write(&iopt->iova_rwsem); + + if (iopt_liveupdate_immutable(iopt)) { + rc = -EBUSY; + goto out_unlock_iova; + } + while ((area = iopt_area_iter_first(iopt, start, last))) { unsigned long area_last = iopt_area_last_iova(area); unsigned long area_first = iopt_area_iova(area); diff --git a/drivers/iommu/iommufd/io_pagetable.h b/drivers/iommu/iommufd/io_pagetable.h index 27e3e311d395..207ff368d412 100644 --- a/drivers/iommu/iommufd/io_pagetable.h +++ b/drivers/iommu/iommufd/io_pagetable.h @@ -234,6 +234,7 @@ struct iopt_pages { struct { /* IOPT_ADDRESS_FILE */ struct file *file; unsigned long start; + u32 seals; }; /* IOPT_ADDRESS_DMABUF */ struct iopt_pages_dmabuf dmabuf; diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h index 111f4d42e210..3c88aa115d08 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -98,6 +98,9 @@ struct io_pagetable { /* IOVA that cannot be allocated, struct iopt_reserved */ struct rb_root_cached reserved_itree; u8 disable_large_pages; +#ifdef CONFIG_IOMMU_LIVEUPDATE + bool liveupdate_immutable; +#endif unsigned long iova_alignment; }; @@ -379,7 +382,7 @@ struct iommufd_hwpt_paging { bool enforce_cache_coherency : 1; bool nest_parent : 1; #ifdef CONFIG_IOMMU_LIVEUPDATE - bool liveupdate_preserve : 1; + bool liveupdate_preserved : 1; u64 liveupdate_token; #endif /* Head at iommufd_ioas::hwpt_list */ @@ -716,12 +719,34 @@ iommufd_get_vdevice(struct iommufd_ctx *ictx, u32 id) } #ifdef CONFIG_IOMMU_LIVEUPDATE +int iommufd_liveupdate_register(void); +void iommufd_liveupdate_unregister(void); + int iommufd_hwpt_liveupdate_mark_preserve(struct iommufd_ucmd *ucmd); + +static inline bool iopt_liveupdate_immutable(const struct io_pagetable *iopt) +{ + return iopt->liveupdate_immutable; +} #else +static inline int iommufd_liveupdate_register(void) +{ + return 0; +} + +static inline void iommufd_liveupdate_unregister(void) +{ +} + static inline int iommufd_hwpt_liveupdate_mark_preserve(struct iommufd_ucmd *ucmd) { return -ENOTTY; } + +static inline bool iopt_liveupdate_immutable(const struct io_pagetable *iopt) +{ + return false; +} #endif #ifdef CONFIG_IOMMUFD_TEST diff --git a/drivers/iommu/iommufd/liveupdate.c b/drivers/iommu/iommufd/liveupdate.c index 2d3abfa9e9f8..3cb220557d0d 100644 --- a/drivers/iommu/iommufd/liveupdate.c +++ b/drivers/iommu/iommufd/liveupdate.c @@ -9,9 +9,22 @@ #include #include +#include +#include #include +#include +#include +#include #include "iommufd_private.h" +#include "io_pagetable.h" + +static void ioas_set_immutable(struct iommufd_ioas *ioas, bool immutable) +{ + down_write(&ioas->iopt.domains_rwsem); + ioas->iopt.liveupdate_immutable = immutable; + up_write(&ioas->iopt.domains_rwsem); +} int iommufd_hwpt_liveupdate_mark_preserve(struct iommufd_ucmd *ucmd) { @@ -50,3 +63,277 @@ int iommufd_hwpt_liveupdate_mark_preserve(struct iommufd_ucmd *ucmd) iommufd_put_object(ictx, &hwpt_target->common.obj); return rc; } + +static int check_iopt_pages_preserved(struct liveupdate_session *s, + struct iommufd_hwpt_paging *hwpt) +{ + u32 req_seals = F_SEAL_SEAL | F_SEAL_GROW | F_SEAL_SHRINK; + struct iopt_area *area; + int ret = 0; + + down_read(&hwpt->ioas->iopt.iova_rwsem); + for (area = iopt_area_iter_first(&hwpt->ioas->iopt, 0, ULONG_MAX); area; + area = iopt_area_iter_next(area, 0, ULONG_MAX)) { + struct iopt_pages *pages = area->pages; + + /* Only allow file based mapping */ + if (pages->type != IOPT_ADDRESS_FILE) { + ret = -EINVAL; + break; + } + + /* + * When this memory file was mapped it should be sealed and seal + * should be sealed. This means that since mapping was done the + * memory file was not grown or shrink and the pages being used + * until now remain pinned and preserved. + */ + if ((pages->seals & req_seals) != req_seals) { + ret = -EINVAL; + break; + } + + /* Make sure that the file was preserved. */ + ret = liveupdate_get_token_outgoing(s, pages->file, NULL); + if (ret) + break; + } + up_read(&hwpt->ioas->iopt.iova_rwsem); + + return ret; +} + +static int iommufd_preserve_hwpt(struct iommufd_hwpt_paging *hwpt, + struct iommufd_hwpt_ser *hwpt_ser, + struct liveupdate_session *session) +{ + struct iommu_domain_ser *domain_ser; + bool ioas_made_immutable = false; + int rc; + + if (!hwpt->ioas->iopt.liveupdate_immutable) { + /* + * Make IOAS immutable so the DMA mappings do not change while + * the HWPT is preserved. Since one IOAS can have multiple + * HWPTs, if an error occurs this call needs to make the IOAS + * mutable again if it was the one that made it immutable. + */ + ioas_made_immutable = true; + ioas_set_immutable(hwpt->ioas, true); + + rc = check_iopt_pages_preserved(session, hwpt); + if (rc) + goto err; + } + + hwpt_ser->token = hwpt->liveupdate_token; + hwpt_ser->reclaimed = false; + + rc = iommu_domain_preserve(hwpt->common.domain, &domain_ser); + if (rc < 0) + goto err; + + hwpt_ser->domain_data = virt_to_phys(domain_ser); + return 0; + +err: + if (ioas_made_immutable) + ioas_set_immutable(hwpt->ioas, false); + + return rc; +} + +static void _iommufd_unpreserve(struct iommufd_ctx *ictx, + struct iommufd_ser *ser) +{ + struct iommufd_hwpt_paging *hwpt; + struct iommufd_object *obj; + unsigned long index; + + xa_lock(&ictx->objects); + xa_for_each_marked(&ictx->objects, index, obj, IOMMUFD_OBJ_LIVEUPDATE_MARK) { + if (obj->type != IOMMUFD_OBJ_HWPT_PAGING) + continue; + + hwpt = to_hwpt_paging(container_of(obj, struct iommufd_hw_pagetable, obj)); + if (!hwpt->liveupdate_preserved) + continue; + + xa_unlock(&ictx->objects); + + iommu_domain_unpreserve(hwpt->common.domain); + if (hwpt->ioas->iopt.liveupdate_immutable) + ioas_set_immutable(hwpt->ioas, false); + + hwpt->liveupdate_preserved = false; + iommufd_put_object(ictx, obj); + + xa_lock(&ictx->objects); + } + xa_unlock(&ictx->objects); + + kho_unpreserve_free(ser); +} + +static int iommufd_liveupdate_preserve(struct liveupdate_file_op_args *args) +{ + struct iommufd_ctx *ictx = iommufd_ctx_from_file(args->file); + struct iommufd_hwpt_paging *hwpt; + struct iommufd_ser *iommufd_ser; + struct iommufd_object *obj; + unsigned int nr_hwpts; + unsigned long index; + unsigned int i; + void *mem; + int rc; + + if (IS_ERR(ictx)) + return PTR_ERR(ictx); + + mutex_lock(&ictx->liveupdate_mutex); + + /* Count the number of HWPTs to preserve */ + nr_hwpts = 0; + xa_lock(&ictx->objects); + xa_for_each_marked(&ictx->objects, index, obj, IOMMUFD_OBJ_LIVEUPDATE_MARK) { + if (obj->type != IOMMUFD_OBJ_HWPT_PAGING) + continue; + + hwpt = to_hwpt_paging(container_of(obj, struct iommufd_hw_pagetable, obj)); + if (!hwpt->common.domain) { + rc = -EINVAL; + xa_unlock(&ictx->objects); + goto out_unlock; + } + nr_hwpts++; + } + xa_unlock(&ictx->objects); + + mem = kho_alloc_preserve(struct_size(iommufd_ser, + hwpt_array, nr_hwpts)); + if (!mem) { + rc = -ENOMEM; + goto out_unlock; + } + + iommufd_ser = mem; + iommufd_ser->nr_hwpts = nr_hwpts; + + /* Preserve HWPTs */ + i = 0; + xa_lock(&ictx->objects); + xa_for_each_marked(&ictx->objects, index, obj, IOMMUFD_OBJ_LIVEUPDATE_MARK) { + if (obj->type != IOMMUFD_OBJ_HWPT_PAGING) + continue; + + if (!iommufd_lock_obj(obj)) { + rc = -ENOENT; + xa_unlock(&ictx->objects); + goto out_unpreserve; + } + + /* + * HWPT is locked so it will not be destroyed. The xarray lock + * can be released here before preserving the HWPT. + */ + xa_unlock(&ictx->objects); + hwpt = to_hwpt_paging(container_of(obj, struct iommufd_hw_pagetable, obj)); + rc = iommufd_preserve_hwpt(hwpt, &iommufd_ser->hwpt_array[i++], args->session); + if (rc) { + iommufd_put_object(ictx, obj); + goto out_unpreserve; + } + + /* Mark as preserved */ + hwpt->liveupdate_preserved = true; + xa_lock(&ictx->objects); + } + xa_unlock(&ictx->objects); + + args->serialized_data = virt_to_phys(iommufd_ser); + mutex_unlock(&ictx->liveupdate_mutex); + iommufd_ctx_put(ictx); + return 0; + +out_unpreserve: + _iommufd_unpreserve(ictx, iommufd_ser); +out_unlock: + mutex_unlock(&ictx->liveupdate_mutex); + iommufd_ctx_put(ictx); + return rc; +} + +static void iommufd_liveupdate_unpreserve(struct liveupdate_file_op_args *args) +{ + struct iommufd_ctx *ictx = iommufd_ctx_from_file(args->file); + + if (WARN_ON(IS_ERR(ictx))) + return; + + mutex_lock(&ictx->liveupdate_mutex); + _iommufd_unpreserve(ictx, phys_to_virt(args->serialized_data)); + mutex_unlock(&ictx->liveupdate_mutex); + + iommufd_ctx_put(ictx); +} + +static int iommufd_liveupdate_retrieve(struct liveupdate_file_op_args *args) +{ + return -EOPNOTSUPP; +} + +static bool iommufd_liveupdate_can_finish(struct liveupdate_file_op_args *args) +{ + return false; +} + +static void iommufd_liveupdate_finish(struct liveupdate_file_op_args *args) +{ +} + +static bool iommufd_liveupdate_can_preserve(struct liveupdate_file_handler *handler, + struct file *file) +{ + struct iommufd_ctx *ictx = iommufd_ctx_from_file(file); + + if (IS_ERR(ictx)) + return false; + + iommufd_ctx_put(ictx); + return true; +} + +static struct liveupdate_file_ops iommufd_ser_file_ops = { + .can_preserve = iommufd_liveupdate_can_preserve, + .preserve = iommufd_liveupdate_preserve, + .unpreserve = iommufd_liveupdate_unpreserve, + .retrieve = iommufd_liveupdate_retrieve, + .can_finish = iommufd_liveupdate_can_finish, + .finish = iommufd_liveupdate_finish, +}; + +static struct liveupdate_file_handler iommufd_ser_handler = { + .compatible = IOMMUFD_LUO_COMPATIBLE, + .ops = &iommufd_ser_file_ops, +}; + +int iommufd_liveupdate_register(void) +{ + int ret; + + ret = liveupdate_register_file_handler(&iommufd_ser_handler); + if (ret) + return ret; + + ret = iommu_liveupdate_register_flb(&iommufd_ser_handler); + if (ret) + liveupdate_unregister_file_handler(&iommufd_ser_handler); + + return ret; +} + +void iommufd_liveupdate_unregister(void) +{ + iommu_liveupdate_unregister_flb(&iommufd_ser_handler); + liveupdate_unregister_file_handler(&iommufd_ser_handler); +} diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c index 0114c1520db4..0a7e7bb586d7 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -782,11 +782,18 @@ static int __init iommufd_init(void) if (ret) goto err_misc; } - ret = iommufd_test_init(); + + ret = iommufd_liveupdate_register(); if (ret) goto err_vfio_misc; + + ret = iommufd_test_init(); + if (ret) + goto err_liveupdate; return 0; +err_liveupdate: + iommufd_liveupdate_unregister(); err_vfio_misc: if (IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER)) misc_deregister(&vfio_misc_dev); @@ -798,6 +805,7 @@ static int __init iommufd_init(void) static void __exit iommufd_exit(void) { iommufd_test_exit(); + iommufd_liveupdate_unregister(); if (IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER)) misc_deregister(&vfio_misc_dev); misc_deregister(&iommu_misc_dev); diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c index 9bdb2945afe1..3b0c0acb8856 100644 --- a/drivers/iommu/iommufd/pages.c +++ b/drivers/iommu/iommufd/pages.c @@ -55,6 +55,7 @@ #include #include #include +#include #include #include "double_span.h" @@ -1421,6 +1422,7 @@ struct iopt_pages *iopt_alloc_file_pages(struct file *file, { struct iopt_pages *pages; + int seals; pages = iopt_alloc_pages(start_byte, length, writable); if (IS_ERR(pages)) @@ -1428,6 +1430,11 @@ struct iopt_pages *iopt_alloc_file_pages(struct file *file, pages->file = get_file(file); pages->start = start - start_byte; pages->type = IOPT_ADDRESS_FILE; + + seals = memfd_get_seals(file); + if (seals > 0) + pages->seals = seals; + return pages; } diff --git a/include/linux/kho/abi/iommufd.h b/include/linux/kho/abi/iommufd.h new file mode 100644 index 000000000000..e0c13b965cb9 --- /dev/null +++ b/include/linux/kho/abi/iommufd.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Copyright (C) 2026, Google LLC + * Author: Samiullah Khawaja + */ + +#ifndef _LINUX_KHO_ABI_IOMMUFD_H +#define _LINUX_KHO_ABI_IOMMUFD_H + +#include +#include +#include + +/** + * DOC: IOMMUFD Live Update ABI + * + * This header defines the ABI for preserving the state of an IOMMUFD file + * across a kexec reboot using LUO. + * + * This interface is a contract. Any modification to any of the serialization + * structs defined here constitutes a breaking change. Such changes require + * incrementing the version number in the IOMMUFD_LUO_COMPATIBLE string. + */ + +#define IOMMUFD_LUO_COMPATIBLE "iommufd-v1" + +/** + * struct iommu_hwpt_ser - IOMMUFD HWPT serialized state + * @domain_data: Physical address of the serialized state of associated domain + * @token: User provided token + * @reclaimed: Whether the HWPT is reclaimed + */ +struct iommufd_hwpt_ser { + u64 domain_data; + u64 token; + u8 reclaimed; + u8 padding[7]; +} __packed; + +/** + * struct iommu_ser - IOMMUFD serialized state + * @nr_hwpts: Number of preserved HWPTs + * @hwpt_array: Array of serialized state of preserved HWPTs + */ +struct iommufd_ser { + u64 nr_hwpts; + struct iommufd_hwpt_ser hwpt_array[]; +} __packed; + +#endif /* _LINUX_KHO_ABI_IOMMUFD_H */ -- 2.54.0.545.g6539524ca2-goog