[Xen-devel] [PATCH] VT-d: make scope parsing code type safe

["Jan Beulich" <JBeulich@xxxxxxxx>]

Rather than requiring the scopes to be the first members of their
respective structures (so that casts can be used to switch between the
different views), properly use types and container_of().

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/drivers/passthrough/vtd/dmar.c
+++ b/xen/drivers/passthrough/vtd/dmar.c
@@ -304,13 +304,15 @@ static int __init scope_device_count(con
 
 
 static int __init acpi_parse_dev_scope(
-    const void *start, const void *end, void *acpi_entry, int type, u16 seg)
+    const void *start, const void *end, struct dmar_scope *scope,
+    int type, u16 seg)
 {
-    struct dmar_scope *scope = acpi_entry;
     struct acpi_ioapic_unit *acpi_ioapic_unit;
     const struct acpi_dmar_device_scope *acpi_scope;
     u16 bus, sub_bus, sec_bus;
     const struct acpi_dmar_pci_path *path;
+    struct acpi_drhd_unit *drhd = type == DMAR_TYPE ?
+        container_of(scope, struct acpi_drhd_unit, scope) : NULL;
     int depth, cnt, didx = 0;
 
     if ( (cnt = scope_device_count(start, end)) < 0 )
@@ -359,9 +361,8 @@ static int __init acpi_parse_dev_scope(
                 dprintk(VTDPREFIX, " MSI HPET: %04x:%02x:%02x.%u\n",
                         seg, bus, path->dev, path->fn);
 
-            if ( type == DMAR_TYPE )
+            if ( drhd )
             {
-                struct acpi_drhd_unit *drhd = acpi_entry;
                 struct acpi_hpet_unit *acpi_hpet_unit;
 
                 acpi_hpet_unit = xmalloc(struct acpi_hpet_unit);
@@ -381,10 +382,8 @@ static int __init acpi_parse_dev_scope(
                 dprintk(VTDPREFIX, " endpoint: %04x:%02x:%02x.%u\n",
                         seg, bus, path->dev, path->fn);
 
-            if ( type == DMAR_TYPE )
+            if ( drhd )
             {
-                struct acpi_drhd_unit *drhd = acpi_entry;
-
                 if ( (seg == 0) && (bus == 0) && (path->dev == 2) &&
                      (path->fn == 0) )
                     igd_drhd_address = drhd->address;
@@ -397,9 +396,8 @@ static int __init acpi_parse_dev_scope(
                 dprintk(VTDPREFIX, " IOAPIC: %04x:%02x:%02x.%u\n",
                         seg, bus, path->dev, path->fn);
 
-            if ( type == DMAR_TYPE )
+            if ( drhd )
             {
-                struct acpi_drhd_unit *drhd = acpi_entry;
                 acpi_ioapic_unit = xmalloc(struct acpi_ioapic_unit);
                 if ( !acpi_ioapic_unit )
                     return -ENOMEM;
@@ -463,7 +461,7 @@ acpi_parse_one_drhd(struct acpi_dmar_hea
     dev_scope_start = (void *)(drhd + 1);
     dev_scope_end = ((void *)drhd) + header->length;
     ret = acpi_parse_dev_scope(dev_scope_start, dev_scope_end,
-                               dmaru, DMAR_TYPE, drhd->segment);
+                               &dmaru->scope, DMAR_TYPE, drhd->segment);
 
     if ( dmaru->include_all )
     {
@@ -590,7 +588,7 @@ acpi_parse_one_rmrr(struct acpi_dmar_hea
     dev_scope_start = (void *)(rmrr + 1);
     dev_scope_end   = ((void *)rmrr) + header->length;
     ret = acpi_parse_dev_scope(dev_scope_start, dev_scope_end,
-                               rmrru, RMRR_TYPE, rmrr->segment);
+                               &rmrru->scope, RMRR_TYPE, rmrr->segment);
 
     if ( ret || (rmrru->scope.devices_cnt == 0) )
         xfree(rmrru);
@@ -683,7 +681,7 @@ acpi_parse_one_atsr(struct acpi_dmar_hea
         dev_scope_start = (void *)(atsr + 1);
         dev_scope_end   = ((void *)atsr) + header->length;
         ret = acpi_parse_dev_scope(dev_scope_start, dev_scope_end,
-                                   atsru, ATSR_TYPE, atsr->segment);
+                                   &atsru->scope, ATSR_TYPE, atsr->segment);
     }
     else
     {
--- a/xen/drivers/passthrough/vtd/dmar.h
+++ b/xen/drivers/passthrough/vtd/dmar.h
@@ -59,7 +59,7 @@ struct dmar_scope {
 };
 
 struct acpi_drhd_unit {
-    struct dmar_scope scope;            /* must be first member of struct */
+    struct dmar_scope scope;
     struct list_head list;
     u64    address;                     /* register base address of the unit */
     u16    segment;
@@ -70,7 +70,7 @@ struct acpi_drhd_unit {
 };
 
 struct acpi_rmrr_unit {
-    struct dmar_scope scope;            /* must be first member of struct */
+    struct dmar_scope scope;
     struct list_head list;
     u64    base_address;
     u64    end_address;
@@ -79,7 +79,7 @@ struct acpi_rmrr_unit {
 };
 
 struct acpi_atsr_unit {
-    struct dmar_scope scope;            /* must be first member of struct */
+    struct dmar_scope scope;
     struct list_head list;
     u16    segment;
     u8     all_ports:1;

Attachment: VT-d-scope-types.patch
Description: Text document

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel