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vmw_balloon: simplifying batch access
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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>
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Nadav Amit authored and Greg Kroah-Hartman committed Sep 25, 2018
1 parent 4c9a7d6 commit 6c94875
Showing 1 changed file with 30 additions and 51 deletions.
81 changes: 30 additions & 51 deletions drivers/misc/vmw_balloon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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) | \
Expand All @@ -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;
Expand Down Expand Up @@ -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];

Expand All @@ -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;

Expand Down Expand Up @@ -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);
}
Expand All @@ -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:
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -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) };
}

/*
Expand Down Expand Up @@ -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
Expand Down

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