intel-iommu: drop VTDBus

We introduce VTDBus structure as an intermediate step for searching
the address space. This works well with SID based matching/lookup. But
when we want to support SID plus PASID based address space lookup,
this intermediate steps turns out to be a burden. So the patch simply
drops the VTDBus structure and use the PCIBus and devfn as the key for
the g_hash_table(). This simplifies the codes and the future PASID
extension.

To prevent being slower for past vtd_find_as_from_bus_num() callers, a
vtd_as cache indexed by the bus number is introduced to store the last
recent search result of a vtd_as belongs to a specific bus.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20221028061436.30093-3-jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>

1 files changed, 2 insertions, 9 deletions

diff --git a/include/hw/i386/intel_iommu.h b/include/hw/i386/intel_iommu.h
index 67653b0..e49fff2 100644
--- a/include/hw/i386/intel_iommu.h
+++ b/include/hw/i386/intel_iommu.h
@@ -58,7 +58,6 @@ typedef struct VTDContextEntry VTDContextEntry;
 typedef struct VTDContextCacheEntry VTDContextCacheEntry;
 typedef struct VTDAddressSpace VTDAddressSpace;
 typedef struct VTDIOTLBEntry VTDIOTLBEntry;
-typedef struct VTDBus VTDBus;
 typedef union VTD_IR_TableEntry VTD_IR_TableEntry;
 typedef union VTD_IR_MSIAddress VTD_IR_MSIAddress;
 typedef struct VTDPASIDDirEntry VTDPASIDDirEntry;
@@ -111,12 +110,6 @@ struct VTDAddressSpace {
     IOVATree *iova_tree;          /* Traces mapped IOVA ranges */
 };
 
-struct VTDBus {
-    PCIBus* bus;		/* A reference to the bus to provide translation for */
-    /* A table of VTDAddressSpace objects indexed by devfn */
-    VTDAddressSpace *dev_as[];
-};
-
 struct VTDIOTLBEntry {
     uint64_t gfn;
     uint16_t domain_id;
@@ -253,8 +246,8 @@ struct IntelIOMMUState {
     uint32_t context_cache_gen;     /* Should be in [1,MAX] */
     GHashTable *iotlb;              /* IOTLB */
 
-    GHashTable *vtd_as_by_busptr;   /* VTDBus objects indexed by PCIBus* reference */
-    VTDBus *vtd_as_by_bus_num[VTD_PCI_BUS_MAX]; /* VTDBus objects indexed by bus number */
+    GHashTable *vtd_address_spaces;             /* VTD address spaces */
+    VTDAddressSpace *vtd_as_cache[VTD_PCI_BUS_MAX]; /* VTD address space cache */
     /* list of registered notifiers */
     QLIST_HEAD(, VTDAddressSpace) vtd_as_with_notifiers;