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intel_iommu: handle invalid ce for shadow sync 

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>
This commit is contained in:
Peter Xu 2018-10-09 15:45:43 +08:00 committed by Michael S. Tsirkin
parent 95ecd3df78
commit c28b535d08
1 changed files with 17 additions and 0 deletions
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17
hw/i386/intel_iommu.c
View File

@ -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;
}