diff options
Diffstat (limited to 'hw/vfio/common.c')
| -rw-r--r-- | hw/vfio/common.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/hw/vfio/common.c b/hw/vfio/common.c index 79628d60ae..f8a2fe8441 100644 --- a/hw/vfio/common.c +++ b/hw/vfio/common.c @@ -728,6 +728,49 @@ static void vfio_register_ram_discard_listener(VFIOContainer *container, vfio_ram_discard_notify_discard, true); ram_discard_manager_register_listener(rdm, &vrdl->listener, section); QLIST_INSERT_HEAD(&container->vrdl_list, vrdl, next); + + /* + * Sanity-check if we have a theoretically problematic setup where we could + * exceed the maximum number of possible DMA mappings over time. We assume + * that each mapped section in the same address space as a RamDiscardManager + * section consumes exactly one DMA mapping, with the exception of + * RamDiscardManager sections; i.e., we don't expect to have gIOMMU sections + * in the same address space as RamDiscardManager sections. + * + * We assume that each section in the address space consumes one memslot. + * We take the number of KVM memory slots as a best guess for the maximum + * number of sections in the address space we could have over time, + * also consuming DMA mappings. + */ + if (container->dma_max_mappings) { + unsigned int vrdl_count = 0, vrdl_mappings = 0, max_memslots = 512; + +#ifdef CONFIG_KVM + if (kvm_enabled()) { + max_memslots = kvm_get_max_memslots(); + } +#endif + + QLIST_FOREACH(vrdl, &container->vrdl_list, next) { + hwaddr start, end; + + start = QEMU_ALIGN_DOWN(vrdl->offset_within_address_space, + vrdl->granularity); + end = ROUND_UP(vrdl->offset_within_address_space + vrdl->size, + vrdl->granularity); + vrdl_mappings += (end - start) / vrdl->granularity; + vrdl_count++; + } + + if (vrdl_mappings + max_memslots - vrdl_count > + container->dma_max_mappings) { + warn_report("%s: possibly running out of DMA mappings. E.g., try" + " increasing the 'block-size' of virtio-mem devies." + " Maximum possible DMA mappings: %d, Maximum possible" + " memslots: %d", __func__, container->dma_max_mappings, + max_memslots); + } + } } static void vfio_unregister_ram_discard_listener(VFIOContainer *container, |