From: Peter Xu <pet...@redhat.com> 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> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1627272 Signed-off-by: Peter Xu <pet...@redhat.com> Reviewed-by: Eric Auger <eric.au...@redhat.com> Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Michael S. Tsirkin <m...@redhat.com> --- hw/i386/intel_iommu.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c index 25e54671f4..f24ebfca1c 100644 --- a/hw/i386/intel_iommu.c +++ b/hw/i386/intel_iommu.c @@ -38,6 +38,7 @@ #include "trace.h" static void vtd_address_space_refresh_all(IntelIOMMUState *s); +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) @@ -1066,11 +1067,27 @@ static int vtd_sync_shadow_page_table(VTDAddressSpace *vtd_as) { int ret; VTDContextEntry ce; + IOMMUNotifier *n; 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); + } + ret = 0; + } return ret; } -- MST
