Add a per-iommu big lock to protect IOMMU status. Currently the only
thing to be protected is the IOTLB cache, since that can be accessed
even without BQL, e.g., in IO dataplane.
Note that device page tables should not need any protection. The safety
of that should be provided by guest OS. E.g., when a page entry is
freed, the guest OS should be responsible to make sure that no device
will be using that page any more.
Reported-by: Fam Zheng<address@hidden>
Signed-off-by: Peter Xu<address@hidden>
---
include/hw/i386/intel_iommu.h | 8 ++++++++
hw/i386/intel_iommu.c | 31 +++++++++++++++++++++++++++++--
2 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 220697253f..1a8ba8e415 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -262,6 +262,14 @@ struct IntelIOMMUState {
uint8_t w1cmask[DMAR_REG_SIZE]; /* RW1C(Write 1 to Clear) bytes */
uint8_t womask[DMAR_REG_SIZE]; /* WO (write only - read returns 0) */
uint32_t version;
+ /*
+ * Protects IOMMU states in general. Normally we don't need to
+ * take this lock when we are with BQL held. However we have code
+ * paths that may run even without BQL. In those cases, we need
+ * to take the lock when we have access to IOMMU state
+ * informations, e.g., the IOTLB.
+ */
+ QemuMutex iommu_lock;