AMD/IOMMU: make phantom functions share interrupt remapping tables

Rather than duplicating entries in amd_iommu_msi_msg_update_ire(), share
the tables. This mainly requires some care while freeing them, to avoid
freeing memory blocks twice.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>

xen/drivers/passthrough/amd/iommu_init.c

@@ -1111,7 +1111,7 @@ static void __init amd_iommu_init_cleanup(void)
         amd_iommu_free_intremap_table(list_first_entry(&amd_iommu_head,
                                                        struct amd_iommu,
                                                        list),
-                                      NULL);
+                                      NULL, 0);
 
     /* free amd iommu list */
     list_for_each_entry_safe ( iommu, next, &amd_iommu_head, list )
@@ -1176,7 +1176,7 @@ int iterate_ivrs_mappings(int (*handler)(u16 seg, struct ivrs_mappings *))
 }
 
 int iterate_ivrs_entries(int (*handler)(const struct amd_iommu *,
-                                        struct ivrs_mappings *))
+                                        struct ivrs_mappings *, uint16_t bdf))
 {
     u16 seg = 0;
     int rc = 0;
@@ -1193,7 +1193,7 @@ int iterate_ivrs_entries(int (*handler)(const struct amd_iommu *,
             const struct amd_iommu *iommu = map[bdf].iommu;
 
             if ( iommu && map[bdf].dte_requestor_id == bdf )
-                rc = handler(iommu, &map[bdf]);
+                rc = handler(iommu, &map[bdf], bdf);
         }
     } while ( !rc && ++seg );
 
@@ -1286,20 +1286,29 @@ static int __init amd_iommu_setup_device_table(
 
             if ( pdev )
             {
-                unsigned int req_id = bdf;
+                ivrs_mappings[bdf].intremap_table =
+                    amd_iommu_alloc_intremap_table(
+                        ivrs_mappings[bdf].iommu,
+                        &ivrs_mappings[bdf].intremap_inuse);
+                if ( !ivrs_mappings[bdf].intremap_table )
+                    return -ENOMEM;
 
-                do {
-                    ivrs_mappings[req_id].intremap_table =
-                        amd_iommu_alloc_intremap_table(
-                            ivrs_mappings[bdf].iommu,
-                            &ivrs_mappings[req_id].intremap_inuse);
-                    if ( !ivrs_mappings[req_id].intremap_table )
-                        return -ENOMEM;
+                if ( pdev->phantom_stride )
+                {
+                    unsigned int req_id = bdf;
 
-                    if ( !pdev->phantom_stride )
-                        break;
-                    req_id += pdev->phantom_stride;
-                } while ( PCI_SLOT(req_id) == pdev->sbdf.dev );
+                    for ( ; ; )
+                    {
+                        req_id += pdev->phantom_stride;
+                        if ( PCI_SLOT(req_id) != pdev->sbdf.dev )
+                            break;
+
+                        ivrs_mappings[req_id].intremap_table =
+                            ivrs_mappings[bdf].intremap_table;
+                        ivrs_mappings[req_id].intremap_inuse =
+                            ivrs_mappings[bdf].intremap_inuse;
+                    }
+                }
             }
 
             amd_iommu_set_intremap_table(

xen/drivers/passthrough/amd/iommu_intr.c

@@ -711,33 +711,20 @@ int amd_iommu_msi_msg_update_ire(
 
     if ( msi_desc->remap_index >= 0 && !msg )
     {
-        do {
-            update_intremap_entry_from_msi_msg(iommu, bdf, nr,
-                                               &msi_desc->remap_index,
-                                               NULL, NULL);
-            if ( !pdev || !pdev->phantom_stride )
-                break;
-            bdf += pdev->phantom_stride;
-        } while ( PCI_SLOT(bdf) == PCI_SLOT(pdev->devfn) );
+        update_intremap_entry_from_msi_msg(iommu, bdf, nr,
+                                           &msi_desc->remap_index,
+                                           NULL, NULL);
 
         for ( i = 0; i < nr; ++i )
             msi_desc[i].remap_index = -1;
-        if ( pdev )
-            bdf = PCI_BDF2(pdev->bus, pdev->devfn);
     }
 
     if ( !msg )
         return 0;
 
-    do {
-        rc = update_intremap_entry_from_msi_msg(iommu, bdf, nr,
-                                                &msi_desc->remap_index,
-                                                msg, &data);
-        if ( rc || !pdev || !pdev->phantom_stride )
-            break;
-        bdf += pdev->phantom_stride;
-    } while ( PCI_SLOT(bdf) == PCI_SLOT(pdev->devfn) );
-
+    rc = update_intremap_entry_from_msi_msg(iommu, bdf, nr,
+                                            &msi_desc->remap_index,
+                                            msg, &data);
     if ( !rc )
     {
         for ( i = 1; i < nr; ++i )
@@ -790,12 +777,27 @@ void amd_iommu_read_msi_from_ire(
 }
 
 int amd_iommu_free_intremap_table(
-    const struct amd_iommu *iommu, struct ivrs_mappings *ivrs_mapping)
+    const struct amd_iommu *iommu, struct ivrs_mappings *ivrs_mapping,
+    uint16_t bdf)
 {
     void **tblp;
 
     if ( ivrs_mapping )
     {
+        unsigned int i;
+
+        /*
+         * PCI device phantom functions use the same tables as their "base"
+         * function: Look ahead to zap the pointers.
+         */
+        for ( i = 1; PCI_FUNC(bdf + i) && bdf + i < ivrs_bdf_entries; ++i )
+            if ( ivrs_mapping[i].intremap_table ==
+                 ivrs_mapping->intremap_table )
+            {
+                ivrs_mapping[i].intremap_table = NULL;
+                ivrs_mapping[i].intremap_inuse = NULL;
+            }
+
         XFREE(ivrs_mapping->intremap_inuse);
         tblp = &ivrs_mapping->intremap_table;
     }
@@ -934,7 +936,8 @@ static void dump_intremap_table(const struct amd_iommu *iommu,
 }
 
 static int dump_intremap_mapping(const struct amd_iommu *iommu,
-                                 struct ivrs_mappings *ivrs_mapping)
+                                 struct ivrs_mappings *ivrs_mapping,
+                                 uint16_t unused)
 {
     unsigned long flags;
 

xen/drivers/passthrough/amd/pci_amd_iommu.c

@@ -519,7 +519,7 @@ static int amd_iommu_remove_device(u8 devfn, struct pci_dev *pdev)
     if ( amd_iommu_perdev_intremap &&
          ivrs_mappings[bdf].dte_requestor_id == bdf &&
          ivrs_mappings[bdf].intremap_table )
-        amd_iommu_free_intremap_table(iommu, &ivrs_mappings[bdf]);
+        amd_iommu_free_intremap_table(iommu, &ivrs_mappings[bdf], bdf);
 
     return 0;
 }

xen/include/asm-x86/amd-iommu.h

@@ -131,7 +131,7 @@ extern u8 ivhd_type;
 struct ivrs_mappings *get_ivrs_mappings(u16 seg);
 int iterate_ivrs_mappings(int (*)(u16 seg, struct ivrs_mappings *));
 int iterate_ivrs_entries(int (*)(const struct amd_iommu *,
-                                 struct ivrs_mappings *));
+                                 struct ivrs_mappings *, uint16_t));
 
 /* iommu tables in guest space */
 struct mmio_reg {

xen/include/asm-x86/hvm/svm/amd-iommu-proto.h

@@ -101,7 +101,7 @@ int amd_iommu_setup_ioapic_remapping(void);
 void *amd_iommu_alloc_intremap_table(
     const struct amd_iommu *, unsigned long **);
 int amd_iommu_free_intremap_table(
-    const struct amd_iommu *, struct ivrs_mappings *);
+    const struct amd_iommu *, struct ivrs_mappings *, uint16_t);
 void amd_iommu_ioapic_update_ire(
     unsigned int apic, unsigned int reg, unsigned int value);
 unsigned int amd_iommu_read_ioapic_from_ire(