* [PATCH 1/2] migration: Receiving a zero page non zero is an error
2023-10-19 8:52 [PATCH 0/2] migration: Simplify handling of zero pages Juan Quintela
@ 2023-10-19 8:52 ` Juan Quintela
2023-10-19 21:22 ` Fabiano Rosas
2023-10-19 8:52 ` [PATCH 2/2] migration: Rename ram_handle_compressed() to ram_handle_zero() Juan Quintela
2023-10-23 15:03 ` [PATCH 0/2] migration: Simplify handling of zero pages Peter Xu
2 siblings, 1 reply; 6+ messages in thread
From: Juan Quintela @ 2023-10-19 8:52 UTC (permalink / raw)
To: qemu-devel
Cc: Li Zhijian, Juan Quintela, Leonardo Bras, Fabiano Rosas, Peter Xu
We don't allow non zero compressed pages since:
commit 3edcd7e6ebae3ef0ac178eed5f4225803159562d
Author: Peter Lieven <pl@kamp.de>
Date: Tue Mar 26 10:58:35 2013 +0100
migration: search for zero instead of dup pages
RDMA case is a bit more complicated, but they don't handle it since:
commit a1febc4950f2c6232c002f401d7cd409f6fa6a88
Author: Richard Henderson <rth@twiddle.net>
Date: Mon Aug 29 11:46:14 2016 -0700
cutils: Export only buffer_is_zero
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
migration/ram.c | 15 +++++++++++----
migration/rdma.c | 6 +++++-
2 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/migration/ram.c b/migration/ram.c
index c844151ee9..0dd8bbb339 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3730,16 +3730,18 @@ int ram_load_postcopy(QEMUFile *f, int channel)
switch (flags & ~RAM_SAVE_FLAG_CONTINUE) {
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
+ if (ch != 0) {
+ error_report("Found a zero page with value %d", ch);
+ ret = -EINVAL;
+ break;
+ }
/*
* Can skip to set page_buffer when
* this is a zero page and (block->page_size == TARGET_PAGE_SIZE).
*/
- if (ch || !matches_target_page_size) {
+ if (!matches_target_page_size) {
memset(page_buffer, ch, TARGET_PAGE_SIZE);
}
- if (ch) {
- tmp_page->all_zero = false;
- }
break;
case RAM_SAVE_FLAG_PAGE:
@@ -4044,6 +4046,11 @@ static int ram_load_precopy(QEMUFile *f)
case RAM_SAVE_FLAG_ZERO:
ch = qemu_get_byte(f);
+ if (ch != 0) {
+ error_report("Found a zero page with value %d", ch);
+ ret = -EINVAL;
+ break;
+ }
ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
break;
diff --git a/migration/rdma.c b/migration/rdma.c
index 2a1852ec7f..2d963fd147 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3592,7 +3592,11 @@ int rdma_registration_handle(QEMUFile *f)
host_addr = block->local_host_addr +
(comp->offset - block->offset);
-
+ if (comp->value) {
+ error_report("rdma: Zero page with non-zero (%d) value",
+ comp->value);
+ goto err;
+ }
ram_handle_compressed(host_addr, comp->value, comp->length);
break;
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/2] migration: Rename ram_handle_compressed() to ram_handle_zero()
2023-10-19 8:52 [PATCH 0/2] migration: Simplify handling of zero pages Juan Quintela
2023-10-19 8:52 ` [PATCH 1/2] migration: Receiving a zero page non zero is an error Juan Quintela
@ 2023-10-19 8:52 ` Juan Quintela
2023-10-19 21:23 ` Fabiano Rosas
2023-10-23 15:03 ` [PATCH 0/2] migration: Simplify handling of zero pages Peter Xu
2 siblings, 1 reply; 6+ messages in thread
From: Juan Quintela @ 2023-10-19 8:52 UTC (permalink / raw)
To: qemu-devel
Cc: Li Zhijian, Juan Quintela, Leonardo Bras, Fabiano Rosas, Peter Xu
Now that we know it only handles zero, we can remove the ch parameter.
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
migration/ram.h | 2 +-
migration/ram.c | 10 +++++-----
migration/rdma.c | 2 +-
3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/migration/ram.h b/migration/ram.h
index 145c915ca7..3f724b2f02 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -60,7 +60,7 @@ int ram_discard_range(const char *block_name, uint64_t start, size_t length);
int ram_postcopy_incoming_init(MigrationIncomingState *mis);
int ram_load_postcopy(QEMUFile *f, int channel);
-void ram_handle_compressed(void *host, uint8_t ch, uint64_t size);
+void ram_handle_zero(void *host, uint64_t size);
void ram_transferred_add(uint64_t bytes);
void ram_release_page(const char *rbname, uint64_t offset);
diff --git a/migration/ram.c b/migration/ram.c
index 0dd8bbb339..132662818b 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3461,7 +3461,7 @@ static inline void *colo_cache_from_block_offset(RAMBlock *block,
}
/**
- * ram_handle_compressed: handle the zero page case
+ * ram_handle_zero: handle the zero page case
*
* If a page (or a whole RDMA chunk) has been
* determined to be zero, then zap it.
@@ -3470,10 +3470,10 @@ static inline void *colo_cache_from_block_offset(RAMBlock *block,
* @ch: what the page is filled from. We only support zero
* @size: size of the zero page
*/
-void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
+void ram_handle_zero(void *host, uint64_t size)
{
- if (ch != 0 || !buffer_is_zero(host, size)) {
- memset(host, ch, size);
+ if (!buffer_is_zero(host, size)) {
+ memset(host, 0, size);
}
}
@@ -4051,7 +4051,7 @@ static int ram_load_precopy(QEMUFile *f)
ret = -EINVAL;
break;
}
- ram_handle_compressed(host, ch, TARGET_PAGE_SIZE);
+ ram_handle_zero(host, TARGET_PAGE_SIZE);
break;
case RAM_SAVE_FLAG_PAGE:
diff --git a/migration/rdma.c b/migration/rdma.c
index 2d963fd147..e3493e3b3e 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -3597,7 +3597,7 @@ int rdma_registration_handle(QEMUFile *f)
comp->value);
goto err;
}
- ram_handle_compressed(host_addr, comp->value, comp->length);
+ ram_handle_zero(host_addr, comp->length);
break;
case RDMA_CONTROL_REGISTER_FINISHED:
--
2.41.0
^ permalink raw reply related [flat|nested] 6+ messages in thread