From a35f2ef3b7376bfd0a57f7844bd7454389aae1fc Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:49:34 +0100 Subject: Xen/x86: don't bail early from clear_foreign_p2m_mapping() Its sibling (set_foreign_p2m_mapping()) as well as the sibling of its only caller (gnttab_map_refs()) don't clean up after themselves in case of error. Higher level callers are expected to do so. However, in order for that to really clean up any partially set up state, the operation should not terminate upon encountering an entry in unexpected state. It is particularly relevant to notice here that set_foreign_p2m_mapping() would skip setting up a p2m entry if its grant mapping failed, but it would continue to set up further p2m entries as long as their mappings succeeded. Arguably down the road set_foreign_p2m_mapping() may want its page state related WARN_ON() also converted to an error return. This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- arch/x86/xen/p2m.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 3301875dd196..ac579c44dd28 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -750,17 +750,15 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops, unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i])); unsigned long pfn = page_to_pfn(pages[i]); - if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) { + if (mfn != INVALID_P2M_ENTRY && (mfn & FOREIGN_FRAME_BIT)) + set_phys_to_machine(pfn, INVALID_P2M_ENTRY); + else ret = -EINVAL; - goto out; - } - - set_phys_to_machine(pfn, INVALID_P2M_ENTRY); } if (kunmap_ops) ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, - kunmap_ops, count); -out: + kunmap_ops, count) ?: ret; + return ret; } EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping); -- cgit v1.2.3 From b512e1b077e5ccdbd6e225b15d934ab12453b70a Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:50:08 +0100 Subject: Xen/x86: also check kernel mapping in set_foreign_p2m_mapping() We should not set up further state if either mapping failed; paying attention to just the user mapping's status isn't enough. Also use GNTST_okay instead of implying its value (zero). This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- arch/x86/xen/p2m.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index ac579c44dd28..b5949e5a83ec 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -712,7 +712,8 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, unsigned long mfn, pfn; /* Do not add to override if the map failed. */ - if (map_ops[i].status) + if (map_ops[i].status != GNTST_okay || + (kmap_ops && kmap_ops[i].status != GNTST_okay)) continue; if (map_ops[i].flags & GNTMAP_contains_pte) { -- cgit v1.2.3 From dbe5283605b3bc12ca45def09cc721a0a5c853a2 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:51:07 +0100 Subject: Xen/gntdev: correct dev_bus_addr handling in gntdev_map_grant_pages() We may not skip setting the field in the unmap structure when GNTMAP_device_map is in use - such an unmap would fail to release the respective resources (a page ref in the hypervisor). Otoh the field doesn't need setting at all when GNTMAP_device_map is not in use. To record the value for unmapping, we also better don't use our local p2m: In particular after a subsequent change it may not have got updated for all the batch elements. Instead it can simply be taken from the respective map's results. We can additionally avoid playing this game altogether for the kernel part of the mappings in (x86) PV mode. This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Stefano Stabellini Signed-off-by: Juergen Gross --- drivers/xen/gntdev.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index a36b71286bcf..aece224a4e70 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -309,18 +309,25 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map) * to the kernel linear addresses of the struct pages. * These ptes are completely different from the user ptes dealt * with find_grant_ptes. + * Note that GNTMAP_device_map isn't needed here: The + * dev_bus_addr output field gets consumed only from ->map_ops, + * and by not requesting it when mapping we also avoid needing + * to mirror dev_bus_addr into ->unmap_ops (and holding an extra + * reference to the page in the hypervisor). */ + unsigned int flags = (map->flags & ~GNTMAP_device_map) | + GNTMAP_host_map; + for (i = 0; i < map->count; i++) { unsigned long address = (unsigned long) pfn_to_kaddr(page_to_pfn(map->pages[i])); BUG_ON(PageHighMem(map->pages[i])); - gnttab_set_map_op(&map->kmap_ops[i], address, - map->flags | GNTMAP_host_map, + gnttab_set_map_op(&map->kmap_ops[i], address, flags, map->grants[i].ref, map->grants[i].domid); gnttab_set_unmap_op(&map->kunmap_ops[i], address, - map->flags | GNTMAP_host_map, -1); + flags, -1); } } @@ -336,17 +343,12 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map) continue; } + if (map->flags & GNTMAP_device_map) + map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr; + map->unmap_ops[i].handle = map->map_ops[i].handle; if (use_ptemod) map->kunmap_ops[i].handle = map->kmap_ops[i].handle; -#ifdef CONFIG_XEN_GRANT_DMA_ALLOC - else if (map->dma_vaddr) { - unsigned long bfn; - - bfn = pfn_to_bfn(page_to_pfn(map->pages[i])); - map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn); - } -#endif } return err; } -- cgit v1.2.3 From ebee0eab08594b2bd5db716288a4f1ae5936e9bc Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:52:27 +0100 Subject: Xen/gntdev: correct error checking in gntdev_map_grant_pages() Failure of the kernel part of the mapping operation should also be indicated as an error to the caller, or else it may assume the respective kernel VA is okay to access. Furthermore gnttab_map_refs() failing still requires recording successfully mapped handles, so they can be unmapped subsequently. This in turn requires there to be a way to tell full hypercall failure from partial success - preset map_op status fields such that they won't "happen" to look as if the operation succeeded. Also again use GNTST_okay instead of implying its value (zero). This is part of XSA-361. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- drivers/xen/gntdev.c | 17 +++++++++-------- include/xen/grant_table.h | 1 + 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index aece224a4e70..5447c5156b2e 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -334,21 +334,22 @@ int gntdev_map_grant_pages(struct gntdev_grant_map *map) pr_debug("map %d+%d\n", map->index, map->count); err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, map->pages, map->count); - if (err) - return err; for (i = 0; i < map->count; i++) { - if (map->map_ops[i].status) { + if (map->map_ops[i].status == GNTST_okay) + map->unmap_ops[i].handle = map->map_ops[i].handle; + else if (!err) err = -EINVAL; - continue; - } if (map->flags & GNTMAP_device_map) map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr; - map->unmap_ops[i].handle = map->map_ops[i].handle; - if (use_ptemod) - map->kunmap_ops[i].handle = map->kmap_ops[i].handle; + if (use_ptemod) { + if (map->kmap_ops[i].status == GNTST_okay) + map->kunmap_ops[i].handle = map->kmap_ops[i].handle; + else if (!err) + err = -EINVAL; + } } return err; } diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h index b9c937b3a149..0b1182a3cf41 100644 --- a/include/xen/grant_table.h +++ b/include/xen/grant_table.h @@ -157,6 +157,7 @@ gnttab_set_map_op(struct gnttab_map_grant_ref *map, phys_addr_t addr, map->flags = flags; map->ref = ref; map->dom = domid; + map->status = 1; /* arbitrary positive value */ } static inline void -- cgit v1.2.3 From 36bf1dfb8b266e089afa9b7b984217f17027bf35 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Mon, 15 Feb 2021 08:53:44 +0100 Subject: xen/arm: don't ignore return errors from set_phys_to_machine set_phys_to_machine can fail due to lack of memory, see the kzalloc call in arch/arm/xen/p2m.c:__set_phys_to_machine_multi. Don't ignore the potential return error in set_foreign_p2m_mapping, returning it to the caller instead. This is part of XSA-361. Signed-off-by: Stefano Stabellini Cc: stable@vger.kernel.org Reviewed-by: Julien Grall Signed-off-by: Juergen Gross --- arch/arm/xen/p2m.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c index e52950a43f2e..fd6e3aafe272 100644 --- a/arch/arm/xen/p2m.c +++ b/arch/arm/xen/p2m.c @@ -95,8 +95,10 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops, for (i = 0; i < count; i++) { if (map_ops[i].status) continue; - set_phys_to_machine(map_ops[i].host_addr >> XEN_PAGE_SHIFT, - map_ops[i].dev_bus_addr >> XEN_PAGE_SHIFT); + if (unlikely(!set_phys_to_machine(map_ops[i].host_addr >> XEN_PAGE_SHIFT, + map_ops[i].dev_bus_addr >> XEN_PAGE_SHIFT))) { + return -ENOMEM; + } } return 0; -- cgit v1.2.3 From 5a264285ed1cd32e26d9de4f3c8c6855e467fd63 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:54:51 +0100 Subject: xen-blkback: don't "handle" error by BUG() In particular -ENOMEM may come back here, from set_foreign_p2m_mapping(). Don't make problems worse, the more that handling elsewhere (together with map's status fields now indicating whether a mapping wasn't even attempted, and hence has to be considered failed) doesn't require this odd way of dealing with errors. This is part of XSA-362. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- drivers/block/xen-blkback/blkback.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index 9ebf53903d7b..ee62b3c0b55a 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -811,10 +811,8 @@ again: break; } - if (segs_to_map) { + if (segs_to_map) ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map); - BUG_ON(ret); - } /* * Now swizzle the MFN in our domain with the MFN from the other domain @@ -830,7 +828,7 @@ again: gnttab_page_cache_put(&ring->free_pages, &pages[seg_idx]->page, 1); pages[seg_idx]->handle = BLKBACK_INVALID_HANDLE; - ret |= 1; + ret |= !ret; goto next; } pages[seg_idx]->handle = map[new_map_idx].handle; -- cgit v1.2.3 From 3194a1746e8aabe86075fd3c5e7cf1f4632d7f16 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:55:31 +0100 Subject: xen-netback: don't "handle" error by BUG() In particular -ENOMEM may come back here, from set_foreign_p2m_mapping(). Don't make problems worse, the more that handling elsewhere (together with map's status fields now indicating whether a mapping wasn't even attempted, and hence has to be considered failed) doesn't require this odd way of dealing with errors. This is part of XSA-362. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- drivers/net/xen-netback/netback.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index bc3421d14576..423667b83751 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -1342,13 +1342,11 @@ int xenvif_tx_action(struct xenvif_queue *queue, int budget) return 0; gnttab_batch_copy(queue->tx_copy_ops, nr_cops); - if (nr_mops != 0) { + if (nr_mops != 0) ret = gnttab_map_refs(queue->tx_map_ops, NULL, queue->pages_to_map, nr_mops); - BUG_ON(ret); - } work_done = xenvif_tx_submit(queue); -- cgit v1.2.3 From 7c77474b2d22176d2bfb592ec74e0f2cb71352c9 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:55:57 +0100 Subject: xen-scsiback: don't "handle" error by BUG() In particular -ENOMEM may come back here, from set_foreign_p2m_mapping(). Don't make problems worse, the more that handling elsewhere (together with map's status fields now indicating whether a mapping wasn't even attempted, and hence has to be considered failed) doesn't require this odd way of dealing with errors. This is part of XSA-362. Signed-off-by: Jan Beulich Cc: stable@vger.kernel.org Reviewed-by: Juergen Gross Signed-off-by: Juergen Gross --- drivers/xen/xen-scsiback.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 862162dca33c..9cd4fe8ce680 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -386,12 +386,12 @@ static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map, return 0; err = gnttab_map_refs(map, NULL, pg, cnt); - BUG_ON(err); for (i = 0; i < cnt; i++) { if (unlikely(map[i].status != GNTST_okay)) { pr_err("invalid buffer -- could not remap it\n"); map[i].handle = SCSIBACK_INVALID_HANDLE; - err = -ENOMEM; + if (!err) + err = -ENOMEM; } else { get_page(pg[i]); } -- cgit v1.2.3 From 871997bc9e423f05c7da7c9178e62dde5df2a7f8 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 15 Feb 2021 08:56:44 +0100 Subject: xen-blkback: fix error handling in xen_blkbk_map() The function uses a goto-based loop, which may lead to an earlier error getting discarded by a later iteration. Exit this ad-hoc loop when an error was encountered. The out-of-memory error path additionally fails to fill a structure field looked at by xen_blkbk_unmap_prepare() before inspecting the handle which does get properly set (to BLKBACK_INVALID_HANDLE). Since the earlier exiting from the ad-hoc loop requires the same field filling (invalidation) as that on the out-of-memory path, fold both paths. While doing so, drop the pr_alert(), as extra log messages aren't going to help the situation (the kernel will log oom conditions already anyway). This is XSA-365. Signed-off-by: Jan Beulich Reviewed-by: Juergen Gross Reviewed-by: Julien Grall Signed-off-by: Juergen Gross --- drivers/block/xen-blkback/blkback.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c index ee62b3c0b55a..da16121140ca 100644 --- a/drivers/block/xen-blkback/blkback.c +++ b/drivers/block/xen-blkback/blkback.c @@ -794,8 +794,13 @@ again: pages[i]->persistent_gnt = persistent_gnt; } else { if (gnttab_page_cache_get(&ring->free_pages, - &pages[i]->page)) - goto out_of_memory; + &pages[i]->page)) { + gnttab_page_cache_put(&ring->free_pages, + pages_to_gnt, + segs_to_map); + ret = -ENOMEM; + goto out; + } addr = vaddr(pages[i]->page); pages_to_gnt[segs_to_map] = pages[i]->page; pages[i]->persistent_gnt = NULL; @@ -880,17 +885,18 @@ next: } segs_to_map = 0; last_map = map_until; - if (map_until != num) + if (!ret && map_until != num) goto again; - return ret; - -out_of_memory: - pr_alert("%s: out of memory\n", __func__); - gnttab_page_cache_put(&ring->free_pages, pages_to_gnt, segs_to_map); - for (i = last_map; i < num; i++) +out: + for (i = last_map; i < num; i++) { + /* Don't zap current batch's valid persistent grants. */ + if(i >= last_map + segs_to_map) + pages[i]->persistent_gnt = NULL; pages[i]->handle = BLKBACK_INVALID_HANDLE; - return -ENOMEM; + } + + return ret; } static int xen_blkbk_map_seg(struct pending_req *pending_req) -- cgit v1.2.3