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[Qemu-devel] [PATCH v2 09/16] postcopy: Use temporary for placing zero h
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PATCH v2 09/16] postcopy: Use temporary for placing zero huge pages |
Date: |
Mon, 6 Feb 2017 17:32:59 +0000 |
From: "Dr. David Alan Gilbert" <address@hidden>
The kernel can't do UFFDIO_ZEROPAGE for huge pages, so we have
to allocate a temporary (always zero) page and use UFFDIO_COPYPAGE
on it.
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
Reviewed-by: Juan Quintela <address@hidden>
---
include/migration/migration.h | 1 +
migration/postcopy-ram.c | 23 +++++++++++++++++++++--
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/include/migration/migration.h b/include/migration/migration.h
index c9c1d5f..bd399fc 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -108,6 +108,7 @@ struct MigrationIncomingState {
QEMUFile *to_src_file;
QemuMutex rp_mutex; /* We send replies from multiple threads */
void *postcopy_tmp_page;
+ void *postcopy_tmp_zero_page;
QEMUBH *bh;
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index a8b7fed..4c736d2 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -324,6 +324,10 @@ int postcopy_ram_incoming_cleanup(MigrationIncomingState
*mis)
munmap(mis->postcopy_tmp_page, mis->largest_page_size);
mis->postcopy_tmp_page = NULL;
}
+ if (mis->postcopy_tmp_zero_page) {
+ munmap(mis->postcopy_tmp_zero_page, mis->largest_page_size);
+ mis->postcopy_tmp_zero_page = NULL;
+ }
trace_postcopy_ram_incoming_cleanup_exit();
return 0;
}
@@ -593,8 +597,23 @@ int postcopy_place_page_zero(MigrationIncomingState *mis,
void *host,
return -e;
}
} else {
- /* TODO: The kernel can't use UFFDIO_ZEROPAGE for hugepages */
- assert(0);
+ /* The kernel can't use UFFDIO_ZEROPAGE for hugepages */
+ if (!mis->postcopy_tmp_zero_page) {
+ mis->postcopy_tmp_zero_page = mmap(NULL, mis->largest_page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS,
+ -1, 0);
+ if (mis->postcopy_tmp_zero_page == MAP_FAILED) {
+ int e = errno;
+ mis->postcopy_tmp_zero_page = NULL;
+ error_report("%s: %s mapping large zero page",
+ __func__, strerror(e));
+ return -e;
+ }
+ memset(mis->postcopy_tmp_zero_page, '\0', mis->largest_page_size);
+ }
+ return postcopy_place_page(mis, host, mis->postcopy_tmp_zero_page,
+ pagesize);
}
return 0;
--
2.9.3
[Qemu-devel] [PATCH v2 07/16] postcopy: Record largest page size, Dr. David Alan Gilbert (git), 2017/02/06