[Xen-devel] [PATCH v7 2/3] AMD/IOMMU: allow callers to request allocate_buffer() to skip its memset()

[Jan Beulich <jbeulich@xxxxxxxx>]

The command ring buffer doesn't need clearing up front in any event.
Subsequently we'll also want to avoid clearing the device tables.

While playing with functions signatures replace undue use of fixed width
types at the same time, and extend this to deallocate_buffer() as well.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v7: New.

--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -994,12 +994,12 @@ static unsigned int __init dt_alloc_size
                                              IOMMU_DEV_TABLE_ENTRY_SIZE);
 }
 
-static void __init deallocate_buffer(void *buf, uint32_t sz)
+static void __init deallocate_buffer(void *buf, unsigned long sz)
 {
-    int order = 0;
     if ( buf )
     {
-        order = get_order_from_bytes(sz);
+        unsigned int order = get_order_from_bytes(sz);
+
         __free_amd_iommu_tables(buf, order);
     }
 }
@@ -1012,10 +1012,11 @@ static void __init deallocate_ring_buffe
     ring_buf->tail = 0;
 }
 
-static void * __init allocate_buffer(uint32_t alloc_size, const char *name)
+static void *__init allocate_buffer(unsigned long alloc_size,
+                                    const char *name, bool clear)
 {
-    void * buffer;
-    int order = get_order_from_bytes(alloc_size);
+    void *buffer;
+    unsigned int order = get_order_from_bytes(alloc_size);
 
     buffer = __alloc_amd_iommu_tables(order);
 
@@ -1025,13 +1026,16 @@ static void * __init allocate_buffer(uin
         return NULL;
     }
 
-    memset(buffer, 0, PAGE_SIZE * (1UL << order));
+    if ( clear )
+        memset(buffer, 0, PAGE_SIZE << order);
+
     return buffer;
 }
 
-static void * __init allocate_ring_buffer(struct ring_buffer *ring_buf,
-                                          uint32_t entry_size,
-                                          uint64_t entries, const char *name)
+static void *__init allocate_ring_buffer(struct ring_buffer *ring_buf,
+                                         unsigned int entry_size,
+                                         unsigned long entries,
+                                         const char *name, bool clear)
 {
     ring_buf->head = 0;
     ring_buf->tail = 0;
@@ -1041,7 +1045,8 @@ static void * __init allocate_ring_buffe
     ring_buf->alloc_size = PAGE_SIZE << get_order_from_bytes(entries *
                                                              entry_size);
     ring_buf->entries = ring_buf->alloc_size / entry_size;
-    ring_buf->buffer = allocate_buffer(ring_buf->alloc_size, name);
+    ring_buf->buffer = allocate_buffer(ring_buf->alloc_size, name, clear);
+
     return ring_buf->buffer;
 }
 
@@ -1050,21 +1055,23 @@ static void * __init allocate_cmd_buffer
     /* allocate 'command buffer' in power of 2 increments of 4K */
     return allocate_ring_buffer(&iommu->cmd_buffer, sizeof(cmd_entry_t),
                                 IOMMU_CMD_BUFFER_DEFAULT_ENTRIES,
-                                "Command Buffer");
+                                "Command Buffer", false);
 }
 
 static void * __init allocate_event_log(struct amd_iommu *iommu)
 {
     /* allocate 'event log' in power of 2 increments of 4K */
     return allocate_ring_buffer(&iommu->event_log, sizeof(event_entry_t),
-                                IOMMU_EVENT_LOG_DEFAULT_ENTRIES, "Event Log");
+                                IOMMU_EVENT_LOG_DEFAULT_ENTRIES, "Event Log",
+                                true);
 }
 
 static void * __init allocate_ppr_log(struct amd_iommu *iommu)
 {
     /* allocate 'ppr log' in power of 2 increments of 4K */
     return allocate_ring_buffer(&iommu->ppr_log, sizeof(ppr_entry_t),
-                                IOMMU_PPR_LOG_DEFAULT_ENTRIES, "PPR Log");
+                                IOMMU_PPR_LOG_DEFAULT_ENTRIES, "PPR Log",
+                                true);
 }
 
 /*
@@ -1257,7 +1264,7 @@ static int __init amd_iommu_setup_device
     {
         /* allocate 'device table' on a 4K boundary */
         dt = IVRS_MAPPINGS_DEVTAB(ivrs_mappings) =
-            allocate_buffer(dt_alloc_size(), "Device Table");
+            allocate_buffer(dt_alloc_size(), "Device Table", true);
     }
     if ( !dt )
         return -ENOMEM;


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