vmw_balloon: simplifying batch access

The use of accessors for batch entries complicates the code and makes it
less readable. Remove it an instead use bit-fields.

Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 5e5f61f..7af70fc 100644 (file)
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -121,24 +121,6 @@ enum vmwballoon_capabilities {
 
 #define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES  (0x03000000)
 
-/* Batch page description */
-
-/*
- * Layout of a page in the batch page:
- *
- * +-------------+----------+--------+
- * |             |          |        |
- * | Page number | Reserved | Status |
- * |             |          |        |
- * +-------------+----------+--------+
- * 64  PAGE_SHIFT          6         0
- *
- * The reserved field should be set to 0.
- */
-#define VMW_BALLOON_BATCH_MAX_PAGES    (PAGE_SIZE / sizeof(u64))
-#define VMW_BALLOON_BATCH_STATUS_MASK  ((1UL << 5) - 1)
-#define VMW_BALLOON_BATCH_PAGE_MASK    (~((1UL << PAGE_SHIFT) - 1))
-
 #define VMW_BALLOON_CMD_WITH_TARGET_MASK                       \
        ((1UL << VMW_BALLOON_CMD_GET_TARGET)            |       \
         (1UL << VMW_BALLOON_CMD_LOCK)                  |       \
@@ -161,27 +143,6 @@ static const char * const vmballoon_cmd_names[] = {
        [VMW_BALLOON_CMD_VMCI_DOORBELL_SET]     = "doorbellSet"
 };
 
-struct vmballoon_batch_page {
-       u64 pages[VMW_BALLOON_BATCH_MAX_PAGES];
-};
-
-static u64 vmballoon_batch_get_pa(struct vmballoon_batch_page *batch, int idx)
-{
-       return batch->pages[idx] & VMW_BALLOON_BATCH_PAGE_MASK;
-}
-
-static int vmballoon_batch_get_status(struct vmballoon_batch_page *batch,
-                               int idx)
-{
-       return (int)(batch->pages[idx] & VMW_BALLOON_BATCH_STATUS_MASK);
-}
-
-static void vmballoon_batch_set_pa(struct vmballoon_batch_page *batch, int idx,
-                               u64 pa)
-{
-       batch->pages[idx] = pa;
-}
-
 #ifdef CONFIG_DEBUG_FS
 struct vmballoon_stats {
        unsigned int timer;
@@ -225,6 +186,19 @@ struct vmballoon_page_size {
        unsigned int n_refused_pages;
 };
 
+/**
+ * struct vmballoon_batch_entry - a batch entry for lock or unlock.
+ *
+ * @status: the status of the operation, which is written by the hypervisor.
+ * @reserved: reserved for future use. Must be set to zero.
+ * @pfn: the physical frame number of the page to be locked or unlocked.
+ */
+struct vmballoon_batch_entry {
+       u64 status : 5;
+       u64 reserved : PAGE_SHIFT - 5;
+       u64 pfn : 52;
+} __packed;
+
 struct vmballoon {
        struct vmballoon_page_size page_sizes[VMW_BALLOON_NUM_PAGE_SIZES];
 
@@ -240,7 +214,14 @@ struct vmballoon {
 
        unsigned long capabilities;
 
-       struct vmballoon_batch_page *batch_page;
+       /**
+        * @batch_page: pointer to communication batch page.
+        *
+        * When batching is used, batch_page points to a page, which holds up to
+        * %VMW_BALLOON_BATCH_MAX_PAGES entries for locking or unlocking.
+        */
+       struct vmballoon_batch_entry *batch_page;
+
        unsigned int batch_max_pages;
        struct page *page;
 
@@ -568,8 +549,7 @@ static int vmballoon_lock_batched_page(struct vmballoon *b,
 
        if (locked > 0) {
                for (i = 0; i < num_pages; i++) {
-                       u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
-                       struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
+                       struct page *p = pfn_to_page(b->batch_page[i].pfn);
 
                        vmballoon_free_page(p, is_2m_pages);
                }
@@ -578,12 +558,11 @@ static int vmballoon_lock_batched_page(struct vmballoon *b,
        }
 
        for (i = 0; i < num_pages; i++) {
-               u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
-               struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
+               struct page *p = pfn_to_page(b->batch_page[i].pfn);
                struct vmballoon_page_size *page_size =
                                &b->page_sizes[is_2m_pages];
 
-               locked = vmballoon_batch_get_status(b->batch_page, i);
+               locked = b->batch_page[i].status;
 
                switch (locked) {
                case VMW_BALLOON_SUCCESS:
@@ -656,12 +635,11 @@ static int vmballoon_unlock_batched_page(struct vmballoon *b,
                ret = -EIO;
 
        for (i = 0; i < num_pages; i++) {
-               u64 pa = vmballoon_batch_get_pa(b->batch_page, i);
-               struct page *p = pfn_to_page(pa >> PAGE_SHIFT);
+               struct page *p = pfn_to_page(b->batch_page[i].pfn);
                struct vmballoon_page_size *page_size =
                                &b->page_sizes[is_2m_pages];
 
-               locked = vmballoon_batch_get_status(b->batch_page, i);
+               locked = b->batch_page[i].status;
                if (!hv_success || locked != VMW_BALLOON_SUCCESS) {
                        /*
                         * That page wasn't successfully unlocked by the
@@ -710,8 +688,8 @@ static void vmballoon_add_page(struct vmballoon *b, int idx, struct page *p)
 static void vmballoon_add_batched_page(struct vmballoon *b, int idx,
                                struct page *p)
 {
-       vmballoon_batch_set_pa(b->batch_page, idx,
-                       (u64)page_to_pfn(p) << PAGE_SHIFT);
+       b->batch_page[idx] = (struct vmballoon_batch_entry)
+                                       { .pfn = page_to_pfn(p) };
 }
 
 /*
@@ -967,7 +945,8 @@ static void vmballoon_reset(struct vmballoon *b)
 
        if ((b->capabilities & VMW_BALLOON_BATCHED_CMDS) != 0) {
                b->ops = &vmballoon_batched_ops;
-               b->batch_max_pages = VMW_BALLOON_BATCH_MAX_PAGES;
+               b->batch_max_pages = PAGE_SIZE / sizeof(struct
+                                                       vmballoon_batch_entry);
                if (!vmballoon_init_batching(b)) {
                        /*
                         * We failed to initialize batching, inform the monitor