From 80fe503d7c126fa2be6cc424593cae6c522f65e0 Mon Sep 17 00:00:00 2001

From: Peter Xu <peterx@redhat.com>

Date: Thu, 8 Nov 2018 05:37:21 +0100

Subject: [PATCH 14/22] intel_iommu: handle invalid ce for shadow sync

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RH-Author: Peter Xu <peterx@redhat.com>

Message-id: <20181108053721.13162-8-peterx@redhat.com>

Patchwork-id: 82958

O-Subject: [RHEL-7.7 qemu-kvm-rhev PATCH 7/7] intel_iommu: handle invalid ce for shadow sync

Bugzilla: 1627272

RH-Acked-by: Auger Eric <eric.auger@redhat.com>

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

RH-Acked-by: Philippe Mathieu-Daudé <philmd@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 <pezhang@redhat.com>

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1627272

Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit c28b535d083d0a263d38d9ceeada83cdae8c64f0)

Signed-off-by: Peter Xu <peterx@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@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 c95128d..12af410 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;

     }

-- 

1.8.3.1