On 15/04/2025 2:33 pm, Stefan Hajnoczi wrote: > On Tue, Apr 15, 2025 at 03:11:00AM -0400, Michael S. Tsirkin wrote: >> On Tue, Apr 15, 2025 at 06:18:08AM +0000, CLEMENT MATHIEU--DRIF wrote: >>> Address space creation might end up being called without holding the >>> bql as it is exposed through the IOMMU ops. >>> >>> Signed-off-by: Clement Mathieu--Drif <clement.mathieu--d...@eviden.com> >> >> >> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> >> >> Stefan, want to pick this one up, too? > > Not yet, it may need to wait until after the release: > - Discussion is still ongoing. > - Is this a regression in 10.0 or a long-standing issue?
It's a long standing issue > - Who is affected and what is the impact? > > There are still a few hours left before -rc4 is tagged. I will merge it > if consensus is reached and the missing information becomes clear. > > Thanks, > Stefan > >> >> >>> --- >>> hw/i386/intel_iommu.c | 10 ++++++++++ >>> 1 file changed, 10 insertions(+) >>> >>> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c >>> index dffd7ee885..fea2220013 100644 >>> --- a/hw/i386/intel_iommu.c >>> +++ b/hw/i386/intel_iommu.c >>> @@ -4216,6 +4216,7 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, >>> PCIBus *bus, >>> vtd_dev_as = g_hash_table_lookup(s->vtd_address_spaces, &key); >>> if (!vtd_dev_as) { >>> struct vtd_as_key *new_key = g_malloc(sizeof(*new_key)); >>> + bool take_bql = !bql_locked(); >>> >>> new_key->bus = bus; >>> new_key->devfn = devfn; >>> @@ -4238,6 +4239,11 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, >>> PCIBus *bus, >>> vtd_dev_as->context_cache_entry.context_cache_gen = 0; >>> vtd_dev_as->iova_tree = iova_tree_new(); >>> >>> + /* Some functions in this branch require the bql, make sure we own >>> it */ >>> + if (take_bql) { >>> + bql_lock(); >>> + } >>> + >>> memory_region_init(&vtd_dev_as->root, OBJECT(s), name, >>> UINT64_MAX); >>> address_space_init(&vtd_dev_as->as, &vtd_dev_as->root, >>> "vtd-root"); >>> >>> @@ -4305,6 +4311,10 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, >>> PCIBus *bus, >>> >>> vtd_switch_address_space(vtd_dev_as); >>> >>> + if (take_bql) { >>> + bql_unlock(); >>> + } >>> + >>> g_hash_table_insert(s->vtd_address_spaces, new_key, vtd_dev_as); >>> } >>> return vtd_dev_as; >>> -- >>> 2.49.0 >>