Re: [Qemu-devel] [PATCH V6 02/10] migration: pass MigrationIncomingState* into migration check functions

[Alexey Perevalov]

On 05/31/2017 08:54 PM, Dr. David Alan Gilbert wrote:
* Alexey Perevalov (a.pereva...@samsung.com) wrote:
That tiny refactoring is necessary to be able to set
UFFD_FEATURE_THREAD_ID while requesting features, and then
to create downtime context in case when kernel supports it.
Signed-off-by: Alexey Perevalov <a.pereva...@samsung.com>
---
  migration/migration.c    |  2 +-
  migration/postcopy-ram.c | 10 +++++-----
  migration/postcopy-ram.h |  2 +-
  migration/savevm.c       |  2 +-
  4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/migration/migration.c b/migration/migration.c
index 0304c01..d735976 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -789,7 +789,7 @@ void 
qmp_migrate_set_capabilities(MigrationCapabilityStatusList *params,
           * special support.
           */
          if (!old_postcopy_cap && runstate_check(RUN_STATE_INMIGRATE) &&
-            !postcopy_ram_supported_by_host()) {
+            !postcopy_ram_supported_by_host(NULL)) {
Why is that NULL rather than migration_incoming_get_current()?
That's on the destination.
In current implementation, AFAIU,
migrate-set-capabilities with postcopy-ram argument should be done on 
source machine only,
and it's not required on destination. And it is unnecessary requirement 
to support userfaultfd on
source and check it there.


Dave

              /* postcopy_ram_supported_by_host will have emitted a more
               * detailed message
               */
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index a0489f6..4adab36 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -59,7 +59,7 @@ struct PostcopyDiscardState {
  #include <sys/eventfd.h>
  #include <linux/userfaultfd.h>
  
-static bool ufd_version_check(int ufd)
+static bool ufd_version_check(int ufd, MigrationIncomingState *mis)
  {
      struct uffdio_api api_struct;
      uint64_t ioctl_mask;
@@ -112,7 +112,7 @@ static int test_range_shared(const char *block_name, void 
*host_addr,
   * normally fine since if the postcopy succeeds it gets turned back on at the
   * end.
   */
-bool postcopy_ram_supported_by_host(void)
+bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
  {
      long pagesize = getpagesize();
      int ufd = -1;
@@ -135,7 +135,7 @@ bool postcopy_ram_supported_by_host(void)
      }
  
      /* Version and features check */
-    if (!ufd_version_check(ufd)) {
+    if (!ufd_version_check(ufd, mis)) {
          goto out;
      }
  
@@ -512,7 +512,7 @@ int postcopy_ram_enable_notify(MigrationIncomingState *mis)
       * Although the host check already tested the API, we need to
       * do the check again as an ABI handshake on the new fd.
       */
-    if (!ufd_version_check(mis->userfault_fd)) {
+    if (!ufd_version_check(mis->userfault_fd, mis)) {
          return -1;
      }
  
@@ -650,7 +650,7 @@ void *postcopy_get_tmp_page(MigrationIncomingState *mis)
  
  #else
  /* No target OS support, stubs just fail */
-bool postcopy_ram_supported_by_host(void)
+bool postcopy_ram_supported_by_host(MigrationIncomingState *mis)
  {
      error_report("%s: No OS support", __func__);
      return false;
diff --git a/migration/postcopy-ram.h b/migration/postcopy-ram.h
index 52d51e8..587a8b8 100644
--- a/migration/postcopy-ram.h
+++ b/migration/postcopy-ram.h
@@ -14,7 +14,7 @@
  #define QEMU_POSTCOPY_RAM_H
  
  /* Return true if the host supports everything we need to do postcopy-ram */
-bool postcopy_ram_supported_by_host(void);
+bool postcopy_ram_supported_by_host(MigrationIncomingState *mis);
  
  /*
   * Make all of RAM sensitive to accesses to areas that haven't yet been 
written
diff --git a/migration/savevm.c b/migration/savevm.c
index f5e8194..61a6df7 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1356,7 +1356,7 @@ static int 
loadvm_postcopy_handle_advise(MigrationIncomingState *mis)
          return -1;
      }
  
-    if (!postcopy_ram_supported_by_host()) {
+    if (!postcopy_ram_supported_by_host(mis)) {
          postcopy_state_set(POSTCOPY_INCOMING_NONE);
          return -1;
      }
--
1.8.3.1

--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK




--
Best regards,
Alexey Perevalov