Re: [RFC V1 10/12] migration/ram: old host address

[Steven Sistare]

On 8/16/2024 1:57 PM, Fabiano Rosas wrote:

Steve Sistare <steven.sist...@oracle.com> writes:

Remember the RAMBlock host address as host_old during migration, for use
by CPR.  The iommufd interface to update the virtual address of DMA
mappings requires it.

Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
  hw/core/machine.c       | 6 ++++++
  include/exec/ramblock.h | 1 +
  migration/migration.h   | 2 ++
  migration/options.c     | 2 ++
  migration/ram.c         | 7 +++++++
  5 files changed, 18 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 9676953..0ac16b8 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -35,6 +35,12 @@
  #include "hw/virtio/virtio-iommu.h"
  #include "audio/audio.h"

+/* TBD: register hw_compat_9_1 with machines */

+GlobalProperty hw_compat_9_1[] = {
+    { "migration", "send-host-old", "off"},
+};
+const size_t hw_compat_9_1_len = G_N_ELEMENTS(hw_compat_9_1);
+
  GlobalProperty hw_compat_9_0[] = {
      {"arm-cpu", "backcompat-cntfrq", "true" },
      {"scsi-disk-base", "migrate-emulated-scsi-request", "false" },
diff --git a/include/exec/ramblock.h b/include/exec/ramblock.h
index 64484cd..8f1c535 100644
--- a/include/exec/ramblock.h
+++ b/include/exec/ramblock.h
@@ -28,6 +28,7 @@ struct RAMBlock {
      struct rcu_head rcu;
      struct MemoryRegion *mr;
      uint8_t *host;
+    uint64_t host_old;
      uint8_t *colo_cache; /* For colo, VM's ram cache */
      ram_addr_t offset;
      ram_addr_t used_length;
diff --git a/migration/migration.h b/migration/migration.h
index 38aa140..b5e3151 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -442,6 +442,8 @@ struct MigrationState {
       */
      uint8_t clear_bitmap_shift;

+ bool send_host_old;

+
      /*
       * This save hostname when out-going migration starts
       */
diff --git a/migration/options.c b/migration/options.c
index 7526f9f..197cb86 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -92,6 +92,8 @@ Property migration_properties[] = {
                        clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT),
      DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState,
                       preempt_pre_7_2, false),
+    DEFINE_PROP_BOOL("send-host-old", MigrationState,
+                     send_host_old, true),

/* Migration parameters */

      DEFINE_PROP_UINT8("x-throttle-trigger-threshold", MigrationState,
diff --git a/migration/ram.c b/migration/ram.c
index 1e1e05e..8644917 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3030,6 +3030,9 @@ static int ram_save_setup(QEMUFile *f, void *opaque, 
Error **errp)
              qemu_put_byte(f, strlen(block->idstr));
              qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
              qemu_put_be64(f, block->used_length);
+            if (migrate_get_current()->send_host_old) {
+                qemu_put_be64(f, (uint64_t)block->host);
+            }

This requires an update of scripts/analyze-migration.py. Could be done
on the side.

Indeed.  Thanks.

- Steve

              if (migrate_postcopy_ram() &&
                  block->page_size != max_hg_page_size) {
                  qemu_put_be64(f, block->page_size);
@@ -4021,6 +4024,10 @@ static int parse_ramblock(QEMUFile *f, RAMBlock *block, 
ram_addr_t length)

assert(block); + if (migrate_get_current()->send_host_old) {

+        block->host_old = qemu_get_be64(f);
+    }
+
      if (migrate_mapped_ram()) {
          parse_ramblock_mapped_ram(f, block, length, &local_err);
          if (local_err) {