@@ -297,6 +297,45 @@ static int vhost_verify_ring_mappings(struct vhost_dev *dev,
return 0;
}
+static struct vhost_memory_region *vhost_dev_find_reg(struct vhost_dev *dev,
+ uint64_t start_addr,
+ uint64_t size)
+{
+ int i, n = dev->mem->nregions;
+ for (i = 0; i < n; ++i) {
+ struct vhost_memory_region *reg = dev->mem->regions + i;
+ if (ranges_overlap(reg->guest_phys_addr, reg->memory_size,
+ start_addr, size)) {
+ return reg;
+ }
+ }
+ return NULL;
+}
+
+static bool vhost_dev_cmp_memory(struct vhost_dev *dev,
+ uint64_t start_addr,
+ uint64_t size,
+ uint64_t uaddr)
+{
+ struct vhost_memory_region *reg = vhost_dev_find_reg(dev, start_addr, size);
+ uint64_t reglast;
+ uint64_t memlast;
+
+ if (!reg) {
+ return true;
+ }
+
+ reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);
+ memlast = range_get_last(start_addr, size);
+
+ /* Need to extend region? */
+ if (start_addr < reg->guest_phys_addr || memlast > reglast) {
+ return true;
+ }
+ /* userspace_addr changed? */
+ return uaddr != reg->userspace_addr + start_addr - reg->guest_phys_addr;
+}
+
static void vhost_client_set_memory(CPUPhysMemoryClient *client,
target_phys_addr_t start_addr,
ram_addr_t size,
@@ -309,6 +348,7 @@ static void vhost_client_set_memory(CPUPhysMemoryClient *client,
(dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
uint64_t log_size;
int r;
+
dev->mem = qemu_realloc(dev->mem, s);
if (log_dirty) {
@@ -317,6 +357,20 @@ static void vhost_client_set_memory(CPUPhysMemoryClient *client,
assert(size);
+ /* Optimize no-change case. At least cirrus_vga does this a lot at this time. */
+ if (flags == IO_MEM_RAM) {
+ if (!vhost_dev_cmp_memory(dev, start_addr, size,
+ (uintptr_t)qemu_get_ram_ptr(phys_offset))) {
+ /* Region exists with same address. Nothing to do. */
+ return;
+ }
+ } else {
+ if (!vhost_dev_find_reg(dev, start_addr, size)) {
+ /* Removing region that we don't access. Nothing to do. */
+ return;
+ }
+ }
+
vhost_dev_unassign_memory(dev, start_addr, size);
if (flags == IO_MEM_RAM) {
/* Add given mapping, merging adjacent regions if any */
Cirrus VGA (at least) calls register memory region with the same values again and again. The registration in vhost-net slows this a lot, optimize by checking that the same data is already registered. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- hw/vhost.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 54 insertions(+), 0 deletions(-)