[Qemu-devel] [PATCH v3 1/5] exec: Change RAMBlockIterFunc definition

[Yury Kotov <yury-kotov@yandex-team.ru>]

Currently, qemu_ram_foreach_* calls RAMBlockIterFunc with many
block-specific arguments. But often iter func needs RAMBlock*.
This refactoring is needed for fast access to RAMBlock flags from
qemu_ram_foreach_block's callback. The only way to achieve this now
is to call qemu_ram_block_from_host (which also enumerates blocks).

So, this patch reduces complexity of
qemu_ram_foreach_block() -> cb() -> qemu_ram_block_from_host()
from O(n^2) to O(n).

Fix RAMBlockIterFunc definition and add some functions to read
RAMBlock* fields witch were passed.

Signed-off-by: Yury Kotov <yury-kotov@yandex-team.ru>
---
 exec.c                    | 21 +++++++++++++++++----
 include/exec/cpu-common.h |  6 ++++--
 migration/postcopy-ram.c  | 36 +++++++++++++++++++++---------------
 migration/rdma.c          |  7 +++++--
 stubs/ram-block.c         | 15 +++++++++++++++
 util/vfio-helpers.c       |  6 +++---
 6 files changed, 65 insertions(+), 26 deletions(-)

diff --git a/exec.c b/exec.c
index 518064530b..bf71462929 100644
--- a/exec.c
+++ b/exec.c
@@ -1972,6 +1972,21 @@ const char *qemu_ram_get_idstr(RAMBlock *rb)
     return rb->idstr;
 }
 
+void *qemu_ram_get_host_addr(RAMBlock *rb)
+{
+    return rb->host;
+}
+
+ram_addr_t qemu_ram_get_offset(RAMBlock *rb)
+{
+    return rb->offset;
+}
+
+ram_addr_t qemu_ram_get_used_length(RAMBlock *rb)
+{
+    return rb->used_length;
+}
+
 bool qemu_ram_is_shared(RAMBlock *rb)
 {
     return rb->flags & RAM_SHARED;
@@ -3961,8 +3976,7 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque)
 
     rcu_read_lock();
     RAMBLOCK_FOREACH(block) {
-        ret = func(block->idstr, block->host, block->offset,
-                   block->used_length, opaque);
+        ret = func(block, opaque);
         if (ret) {
             break;
         }
@@ -3981,8 +3995,7 @@ int qemu_ram_foreach_migratable_block(RAMBlockIterFunc func, void *opaque)
         if (!qemu_ram_is_migratable(block)) {
             continue;
         }
-        ret = func(block->idstr, block->host, block->offset,
-                   block->used_length, opaque);
+        ret = func(block, opaque);
         if (ret) {
             break;
         }
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 63ec1f9b37..9cd1f94bc5 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -72,6 +72,9 @@ ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host);
 void qemu_ram_set_idstr(RAMBlock *block, const char *name, DeviceState *dev);
 void qemu_ram_unset_idstr(RAMBlock *block);
 const char *qemu_ram_get_idstr(RAMBlock *rb);
+void *qemu_ram_get_host_addr(RAMBlock *rb);
+ram_addr_t qemu_ram_get_offset(RAMBlock *rb);
+ram_addr_t qemu_ram_get_used_length(RAMBlock *rb);
 bool qemu_ram_is_shared(RAMBlock *rb);
 bool qemu_ram_is_uf_zeroable(RAMBlock *rb);
 void qemu_ram_set_uf_zeroable(RAMBlock *rb);
@@ -116,8 +119,7 @@ void cpu_flush_icache_range(hwaddr start, hwaddr len);
 extern struct MemoryRegion io_mem_rom;
 extern struct MemoryRegion io_mem_notdirty;
 
-typedef int (RAMBlockIterFunc)(const char *block_name, void *host_addr,
-    ram_addr_t offset, ram_addr_t length, void *opaque);
+typedef int (RAMBlockIterFunc)(RAMBlock *rb, void *opaque);
 
 int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque);
 int qemu_ram_foreach_migratable_block(RAMBlockIterFunc func, void *opaque);
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index fa09dba534..b098816221 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -319,10 +319,10 @@ static bool ufd_check_and_apply(int ufd, MigrationIncomingState *mis)
 
 /* Callback from postcopy_ram_supported_by_host block iterator.
  */
-static int test_ramblock_postcopiable(const char *block_name, void *host_addr,
-                             ram_addr_t offset, ram_addr_t length, void *opaque)
+static int test_ramblock_postcopiable(RAMBlock *rb, void *opaque)
 {
-    RAMBlock *rb = qemu_ram_block_by_name(block_name);
+    const char *block_name = qemu_ram_get_idstr(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     size_t pagesize = qemu_ram_pagesize(rb);
 
     if (length % pagesize) {
@@ -443,9 +443,12 @@ out:
  * must be done right at the start prior to pre-copy.
  * opaque should be the MIS.
  */
-static int init_range(const char *block_name, void *host_addr,
-                      ram_addr_t offset, ram_addr_t length, void *opaque)
+static int init_range(RAMBlock *rb, void *opaque)
 {
+    const char *block_name = qemu_ram_get_idstr(rb);
+    void *host_addr = qemu_ram_get_host_addr(rb);
+    ram_addr_t offset = qemu_ram_get_offset(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     trace_postcopy_init_range(block_name, host_addr, offset, length);
 
     /*
@@ -465,9 +468,12 @@ static int init_range(const char *block_name, void *host_addr,
  * At the end of migration, undo the effects of init_range
  * opaque should be the MIS.
  */
-static int cleanup_range(const char *block_name, void *host_addr,
-                        ram_addr_t offset, ram_addr_t length, void *opaque)
+static int cleanup_range(RAMBlock *rb, void *opaque)
 {
+    const char *block_name = qemu_ram_get_idstr(rb);
+    void *host_addr = qemu_ram_get_host_addr(rb);
+    ram_addr_t offset = qemu_ram_get_offset(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     MigrationIncomingState *mis = opaque;
     struct uffdio_range range_struct;
     trace_postcopy_cleanup_range(block_name, host_addr, offset, length);
@@ -586,9 +592,12 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
 /*
  * Disable huge pages on an area
  */
-static int nhp_range(const char *block_name, void *host_addr,
-                    ram_addr_t offset, ram_addr_t length, void *opaque)
+static int nhp_range(RAMBlock *rb, void *opaque)
 {
+    const char *block_name = qemu_ram_get_idstr(rb);
+    void *host_addr = qemu_ram_get_host_addr(rb);
+    ram_addr_t offset = qemu_ram_get_offset(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     trace_postcopy_nhp_range(block_name, host_addr, offset, length);
 
     /*
@@ -626,15 +635,13 @@ int postcopy_ram_prepare_discard(MigrationIncomingState *mis)
  *   opaque: MigrationIncomingState pointer
  * Returns 0 on success
  */
-static int ram_block_enable_notify(const char *block_name, void *host_addr,
-                                   ram_addr_t offset, ram_addr_t length,
-                                   void *opaque)
+static int ram_block_enable_notify(RAMBlock *rb, void *opaque)
 {
     MigrationIncomingState *mis = opaque;
     struct uffdio_register reg_struct;
 
-    reg_struct.range.start = (uintptr_t)host_addr;
-    reg_struct.range.len = length;
+    reg_struct.range.start = (uintptr_t)qemu_ram_get_host_addr(rb);
+    reg_struct.range.len = qemu_ram_get_used_length(rb);
     reg_struct.mode = UFFDIO_REGISTER_MODE_MISSING;
 
     /* Now tell our userfault_fd that it's responsible for this area */
@@ -647,7 +654,6 @@ static int ram_block_enable_notify(const char *block_name, void *host_addr,
         return -1;
     }
     if (reg_struct.ioctls & ((__u64)1 << _UFFDIO_ZEROPAGE)) {
-        RAMBlock *rb = qemu_ram_block_by_name(block_name);
         qemu_ram_set_uf_zeroable(rb);
     }
 
diff --git a/migration/rdma.c b/migration/rdma.c
index 54a3c11540..7eb38ee764 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -624,9 +624,12 @@ static int rdma_add_block(RDMAContext *rdma, const char *block_name,
  * in advanced before the migration starts. This tells us where the RAM blocks
  * are so that we can register them individually.
  */
-static int qemu_rdma_init_one_block(const char *block_name, void *host_addr,
-    ram_addr_t block_offset, ram_addr_t length, void *opaque)
+static int qemu_rdma_init_one_block(RAMBlock *rb, void *opaque)
 {
+    const char *block_name = qemu_ram_get_idstr(rb);
+    void *host_addr = qemu_ram_get_host_addr(rb);
+    ram_addr_t block_offset = qemu_ram_get_offset(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     return rdma_add_block(opaque, block_name, host_addr, block_offset, length);
 }
 
diff --git a/stubs/ram-block.c b/stubs/ram-block.c
index cfa5d8678f..73c0a3ee08 100644
--- a/stubs/ram-block.c
+++ b/stubs/ram-block.c
@@ -2,6 +2,21 @@
 #include "exec/ramlist.h"
 #include "exec/cpu-common.h"
 
+void *qemu_ram_get_host_addr(RAMBlock *rb)
+{
+    return 0;
+}
+
+ram_addr_t qemu_ram_get_offset(RAMBlock *rb)
+{
+    return 0;
+}
+
+ram_addr_t qemu_ram_get_used_length(RAMBlock *rb)
+{
+    return 0;
+}
+
 void ram_block_notifier_add(RAMBlockNotifier *n)
 {
 }
diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c
index 342d4a2285..2367fe8f7f 100644
--- a/util/vfio-helpers.c
+++ b/util/vfio-helpers.c
@@ -391,10 +391,10 @@ static void qemu_vfio_ram_block_removed(RAMBlockNotifier *n,
     }
 }
 
-static int qemu_vfio_init_ramblock(const char *block_name, void *host_addr,
-                                   ram_addr_t offset, ram_addr_t length,
-                                   void *opaque)
+static int qemu_vfio_init_ramblock(RAMBlock *rb, void *opaque)
 {
+    void *host_addr = qemu_ram_get_host_addr(rb);
+    ram_addr_t length = qemu_ram_get_used_length(rb);
     int ret;
     QEMUVFIOState *s = opaque;
 
-- 
2.20.1