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[Qemu-devel] [PATCH v3 2/2] intel_iommu: handle invalid ce for shadow sy
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v3 2/2] intel_iommu: handle invalid ce for shadow sync |
Date: |
Tue, 9 Oct 2018 15:45:43 +0800 |
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 <address@hidden>
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1627272
Signed-off-by: Peter Xu <address@hidden>
---
hw/i386/intel_iommu.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index d6b4f8705d..6072f9a4e0 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)
{
@@ -1056,11 +1058,27 @@ 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;
}
--
2.17.1