From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60401) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1g0MTT-0006uU-Ib for qemu-devel@nongnu.org; Thu, 13 Sep 2018 03:55:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1g0MTQ-0003ot-CD for qemu-devel@nongnu.org; Thu, 13 Sep 2018 03:55:39 -0400 From: Peter Xu Date: Thu, 13 Sep 2018 15:55:17 +0800 Message-Id: <20180913075517.11140-1-peterx@redhat.com> Subject: [Qemu-devel] [PATCH] intel_iommu: handle invalid ce for shadow sync List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peterx@redhat.com, Pei Zhang , Alex Williamson , Jason Wang , Maxime Coquelin , "Michael S . Tsirkin" , QEMU Stable 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 Tested-by: Pei Zhang CC: Pei Zhang CC: Alex Williamson CC: Jason Wang CC: Maxime Coquelin CC: Michael S. Tsirkin CC: QEMU Stable Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1627272 Signed-off-by: Peter Xu --- 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