There are two callers for vtd_sync_shadow_page_table_range(), one provided a valid context entry and one not. Move that fetching operation into the caller vtd_sync_shadow_page_table() where we need to fetch the context entry.
Meanwhile, we should handle VTD_FR_CONTEXT_ENTRY_P properly when synchronizing shadow page tables. Having invalid context entry there is perfectly valid when we move a device out of an existing domain. When that happens, instead of posting an error we invalidate the whole region. Without this patch, QEMU will crash if we do these steps: (1) start QEMU with VT-d IOMMU and two 10G NICs (ixgbe) (2) bind the NICs with vfio-pci in the guest (3) start testpmd with the NICs applied (4) stop testpmd (5) rebind the NIC back to ixgbe kernel driver The patch should fix it. Reported-by: Pei Zhang <pezh...@redhat.com> Tested-by: Pei Zhang <pezh...@redhat.com> CC: Pei Zhang <pezh...@redhat.com> CC: Alex Williamson <alex.william...@redhat.com> CC: Jason Wang <jasow...@redhat.com> CC: Maxime Coquelin <maxime.coque...@redhat.com> CC: Michael S. Tsirkin <m...@redhat.com> CC: QEMU Stable <qemu-sta...@nongnu.org> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1627272 Signed-off-by: Peter Xu <pet...@redhat.com> --- hw/i386/intel_iommu.c | 54 ++++++++++++++++++++++++++----------------- 1 file changed, 33 insertions(+), 21 deletions(-) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 3dfada19a6..2509520d6f 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -37,6 +37,8 @@ #include "kvm_i386.h" #include "trace.h" +static void vtd_address_space_unmap(VTDAddressSpace *as, IOMMUNotifier *n); + static void vtd_define_quad(IntelIOMMUState *s, hwaddr addr, uint64_t val, uint64_t wmask, uint64_t w1cmask) { @@ -1047,39 +1049,49 @@ static int vtd_sync_shadow_page_table_range(VTDAddressSpace *vtd_as, .notify_unmap = true, .aw = s->aw_bits, .as = vtd_as, + .domain_id = VTD_CONTEXT_ENTRY_DID(ce->hi), }; - VTDContextEntry ce_cache; + + return vtd_page_walk(ce, addr, addr + size, &info); +} + +static int vtd_sync_shadow_page_table(VTDAddressSpace *vtd_as) +{ int ret; + VTDContextEntry ce; + IOMMUNotifier *n; - if (ce) { - /* If the caller provided context entry, use it */ - ce_cache = *ce; - } else { - /* If the caller didn't provide ce, try to fetch */ - ret = vtd_dev_to_context_entry(s, pci_bus_num(vtd_as->bus), - vtd_as->devfn, &ce_cache); - if (ret) { + ret = vtd_dev_to_context_entry(vtd_as->iommu_state, + pci_bus_num(vtd_as->bus), + vtd_as->devfn, &ce); + if (ret) { + if (ret == -VTD_FR_CONTEXT_ENTRY_P) { + /* + * It's a valid scenario to have a context entry that is + * not present. For example, when a device is removed + * from an existing domain then the context entry will be + * zeroed by the guest before it was put into another + * domain. When this happens, instead of synchronizing + * the shadow pages we should invalidate all existing + * mappings and notify the backends. + */ + IOMMU_NOTIFIER_FOREACH(n, &vtd_as->iommu) { + vtd_address_space_unmap(vtd_as, n); + } + } else { /* * This should not really happen, but in case it happens, * we just skip the sync for this time. After all we even * don't have the root table pointer! */ error_report_once("%s: invalid context entry for bus 0x%x" - " devfn 0x%x", - __func__, pci_bus_num(vtd_as->bus), - vtd_as->devfn); - return 0; + " devfn 0x%x", __func__, + pci_bus_num(vtd_as->bus), vtd_as->devfn); } + return 0; } - info.domain_id = VTD_CONTEXT_ENTRY_DID(ce_cache.hi); - - return vtd_page_walk(&ce_cache, addr, addr + size, &info); -} - -static int vtd_sync_shadow_page_table(VTDAddressSpace *vtd_as) -{ - return vtd_sync_shadow_page_table_range(vtd_as, NULL, 0, UINT64_MAX); + return vtd_sync_shadow_page_table_range(vtd_as, &ce, 0, UINT64_MAX); } /* -- 2.17.1
