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virtio-mem: Simplify bitmap handling and virtio_mem_set_block_state() 
Let's separate plug and unplug handling to prepare for future changes
and make the code a bit easier to read -- working on block states
(plugged/unplugged) instead of on a bitmap.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20230523183036.517957-1-david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@davidhildenbrand @mstsirkin
davidhildenbrand authored and mstsirkin committed Jun 23, 2023
1 parent 8eb85fb commit 25c8930
Showing 1 changed file with 66 additions and 50 deletions.
116 changes: 66 additions & 50 deletions hw/virtio/virtio-mem.c
View file
Expand Up @@ -398,33 +398,46 @@ static void virtio_mem_notify_unplug_all(VirtIOMEM *vmem)
}
}

static bool virtio_mem_test_bitmap(const VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size, bool plugged)
static bool virtio_mem_is_range_plugged(const VirtIOMEM *vmem,
uint64_t start_gpa, uint64_t size)
{
const unsigned long first_bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long last_bit = first_bit + (size / vmem->block_size) - 1;
unsigned long found_bit;

/* We fake a shorter bitmap to avoid searching too far. */
if (plugged) {
found_bit = find_next_zero_bit(vmem->bitmap, last_bit + 1, first_bit);
} else {
found_bit = find_next_bit(vmem->bitmap, last_bit + 1, first_bit);
}
found_bit = find_next_zero_bit(vmem->bitmap, last_bit + 1, first_bit);
return found_bit > last_bit;
}

static void virtio_mem_set_bitmap(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size, bool plugged)
static bool virtio_mem_is_range_unplugged(const VirtIOMEM *vmem,
uint64_t start_gpa, uint64_t size)
{
const unsigned long first_bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long last_bit = first_bit + (size / vmem->block_size) - 1;
unsigned long found_bit;

/* We fake a shorter bitmap to avoid searching too far. */
found_bit = find_next_bit(vmem->bitmap, last_bit + 1, first_bit);
return found_bit > last_bit;
}

static void virtio_mem_set_range_plugged(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size)
{
const unsigned long bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long nbits = size / vmem->block_size;

if (plugged) {
bitmap_set(vmem->bitmap, bit, nbits);
} else {
bitmap_clear(vmem->bitmap, bit, nbits);
}
bitmap_set(vmem->bitmap, bit, nbits);
}

static void virtio_mem_set_range_unplugged(VirtIOMEM *vmem, uint64_t start_gpa,
uint64_t size)
{
const unsigned long bit = (start_gpa - vmem->addr) / vmem->block_size;
const unsigned long nbits = size / vmem->block_size;

bitmap_clear(vmem->bitmap, bit, nbits);
}

static void virtio_mem_send_response(VirtIOMEM *vmem, VirtQueueElement *elem,
Expand Down Expand Up @@ -474,6 +487,7 @@ static int virtio_mem_set_block_state(VirtIOMEM *vmem, uint64_t start_gpa,
{
const uint64_t offset = start_gpa - vmem->addr;
RAMBlock *rb = vmem->memdev->mr.ram_block;
int ret = 0;

if (virtio_mem_is_busy()) {
return -EBUSY;
Expand All @@ -484,42 +498,43 @@ static int virtio_mem_set_block_state(VirtIOMEM *vmem, uint64_t start_gpa,
return -EBUSY;
}
virtio_mem_notify_unplug(vmem, offset, size);
} else {
int ret = 0;

if (vmem->prealloc) {
void *area = memory_region_get_ram_ptr(&vmem->memdev->mr) + offset;
int fd = memory_region_get_fd(&vmem->memdev->mr);
Error *local_err = NULL;

qemu_prealloc_mem(fd, area, size, 1, NULL, &local_err);
if (local_err) {
static bool warned;

/*
* Warn only once, we don't want to fill the log with these
* warnings.
*/
if (!warned) {
warn_report_err(local_err);
warned = true;
} else {
error_free(local_err);
}
ret = -EBUSY;
virtio_mem_set_range_unplugged(vmem, start_gpa, size);
return 0;
}

if (vmem->prealloc) {
void *area = memory_region_get_ram_ptr(&vmem->memdev->mr) + offset;
int fd = memory_region_get_fd(&vmem->memdev->mr);
Error *local_err = NULL;

qemu_prealloc_mem(fd, area, size, 1, NULL, &local_err);
if (local_err) {
static bool warned;

/*
* Warn only once, we don't want to fill the log with these
* warnings.
*/
if (!warned) {
warn_report_err(local_err);
warned = true;
} else {
error_free(local_err);
}
ret = -EBUSY;
}
if (!ret) {
ret = virtio_mem_notify_plug(vmem, offset, size);
}
}

if (ret) {
/* Could be preallocation or a notifier populated memory. */
ram_block_discard_range(vmem->memdev->mr.ram_block, offset, size);
return -EBUSY;
}
if (!ret) {
ret = virtio_mem_notify_plug(vmem, offset, size);
}
virtio_mem_set_bitmap(vmem, start_gpa, size, plug);
if (ret) {
/* Could be preallocation or a notifier populated memory. */
ram_block_discard_range(vmem->memdev->mr.ram_block, offset, size);
return -EBUSY;
}

virtio_mem_set_range_plugged(vmem, start_gpa, size);
return 0;
}

Expand All @@ -538,7 +553,8 @@ static int virtio_mem_state_change_request(VirtIOMEM *vmem, uint64_t gpa,
}

/* test if really all blocks are in the opposite state */
if (!virtio_mem_test_bitmap(vmem, gpa, size, !plug)) {
if ((plug && !virtio_mem_is_range_unplugged(vmem, gpa, size)) ||
(!plug && !virtio_mem_is_range_plugged(vmem, gpa, size))) {
return VIRTIO_MEM_RESP_ERROR;
}

Expand Down Expand Up @@ -651,9 +667,9 @@ static void virtio_mem_state_request(VirtIOMEM *vmem, VirtQueueElement *elem,
return;
}

if (virtio_mem_test_bitmap(vmem, gpa, size, true)) {
if (virtio_mem_is_range_plugged(vmem, gpa, size)) {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_PLUGGED);
} else if (virtio_mem_test_bitmap(vmem, gpa, size, false)) {
} else if (virtio_mem_is_range_unplugged(vmem, gpa, size)) {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_UNPLUGGED);
} else {
resp.u.state.state = cpu_to_le16(VIRTIO_MEM_STATE_MIXED);
Expand Down Expand Up @@ -1372,7 +1388,7 @@ static bool virtio_mem_rdm_is_populated(const RamDiscardManager *rdm,
return false;
}

return virtio_mem_test_bitmap(vmem, start_gpa, end_gpa - start_gpa, true);
return virtio_mem_is_range_plugged(vmem, start_gpa, end_gpa - start_gpa);
}

struct VirtIOMEMReplayData {
Expand Down

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