Allocate anonymous memory using memfd_create if the memfd-alloc option is
set.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
exec.c | 38 ++++++++++++++++++++++++++++++--------
include/sysemu/sysemu.h | 1 +
qemu-options.hx | 11 +++++++++++
softmmu/vl.c | 4 ++++
trace-events | 1 +
5 files changed, 47 insertions(+), 8 deletions(-)
diff --git a/exec.c b/exec.c
index d1f31b4..6da6590 100644
--- a/exec.c
+++ b/exec.c
@@ -67,6 +67,7 @@
#include "exec/log.h"
#include "qemu/pmem.h"
+#include "qemu/memfd.h"
#include "migration/vmstate.h"
@@ -2231,34 +2232,55 @@ static void ram_block_add(RAMBlock *new_block, Error
**errp, bool shared)
{
RAMBlock *block;
RAMBlock *last_block = NULL;
+ struct MemoryRegion *mr = new_block->mr;
ram_addr_t old_ram_size, new_ram_size;
Error *err = NULL;
+ const char *name;
+ void *addr = 0;
+ size_t maxlen;
old_ram_size = last_ram_page();
qemu_mutex_lock_ramlist();
- new_block->offset = find_ram_offset(new_block->max_length);
+ maxlen = new_block->max_length;
+ new_block->offset = find_ram_offset(maxlen);
if (!new_block->host) {
if (xen_enabled()) {
- xen_ram_alloc(new_block->offset, new_block->max_length,
- new_block->mr, &err);
+ xen_ram_alloc(new_block->offset, maxlen, new_block->mr, &err);
if (err) {
error_propagate(errp, err);
qemu_mutex_unlock_ramlist();
return;
}
} else {
- new_block->host = phys_mem_alloc(new_block->max_length,
- &new_block->mr->align, shared);
- if (!new_block->host) {
+ name = memory_region_name(new_block->mr);
+ if (memfd_alloc) {
+ int mfd = -1; /* placeholder until next patch */
+ mr->align = QEMU_VMALLOC_ALIGN;
+ if (mfd < 0) {
+ mfd = qemu_memfd_create(name, maxlen + mr->align,
+ 0, 0, 0, &err);
+ if (mfd < 0) {
+ return;
+ }
+ }
+ new_block->flags |= RAM_SHARED;
+ addr = file_ram_alloc(new_block, maxlen, mfd, false, errp);
+ trace_anon_memfd_alloc(name, maxlen, addr, mfd);
+ } else {
+ addr = phys_mem_alloc(maxlen, &mr->align, shared);
+ }
+
+ if (!addr) {
error_setg_errno(errp, errno,
"cannot set up guest memory '%s'",
- memory_region_name(new_block->mr));
+ name);
qemu_mutex_unlock_ramlist();
return;
}
- memory_try_enable_merging(new_block->host, new_block->max_length);
+ memory_try_enable_merging(addr, maxlen);
+ new_block->host = addr;
}
}
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 4b6a5c4..408eb56 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -13,6 +13,7 @@ extern int only_migratable;
extern const char *qemu_name;
extern QemuUUID qemu_uuid;
extern bool qemu_uuid_set;
+extern bool memfd_alloc;
void qemu_add_data_dir(const char *path);
diff --git a/qemu-options.hx b/qemu-options.hx
index 708583b..455b43b7 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4094,6 +4094,17 @@ SRST
an unmigratable state.
ERST
+#ifdef __linux__
+DEF("memfd-alloc", 0, QEMU_OPTION_memfd_alloc, \
+ "-memfd-alloc allocate anonymous memory using memfd_create\n",
+ QEMU_ARCH_ALL)
+#endif
+
+SRST
+``-memfd-alloc``
+ Allocate anonymous memory using memfd_create (Linux only).
+ERST
+
DEF("nodefaults", 0, QEMU_OPTION_nodefaults, \
"-nodefaults don't create default devices\n", QEMU_ARCH_ALL)
SRST
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 4eb9d1f..5668e2b 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -164,6 +164,7 @@ bool boot_strict;
uint8_t *boot_splash_filedata;
int only_migratable; /* turn it off unless user states otherwise */
bool wakeup_suspend_enabled;
+bool memfd_alloc;
int icount_align_option;
@@ -3635,6 +3636,9 @@ void qemu_init(int argc, char **argv, char **envp)
case QEMU_OPTION_only_migratable:
only_migratable = 1;
break;
+ case QEMU_OPTION_memfd_alloc:
+ memfd_alloc = true;
+ break;
case QEMU_OPTION_nodefaults:
has_defaults = 0;
break;
diff --git a/trace-events b/trace-events
index 42107eb..ed46c4d 100644
--- a/trace-events
+++ b/trace-events
@@ -54,6 +54,7 @@ find_ram_offset_loop(uint64_t size, uint64_t candidate,
uint64_t offset, uint64_
ram_block_discard_range(const char *rbname, void *hva, size_t length, bool
need_madvise, bool need_fallocate, int ret) "%s@%p + 0x%zx: madvise: %d
fallocate: %d ret: %d"
memory_notdirty_write_access(uint64_t vaddr, uint64_t ram_addr, unsigned size)
"0x%" PRIx64 " ram_addr 0x%" PRIx64 " size %u"
memory_notdirty_set_dirty(uint64_t vaddr) "0x%" PRIx64
+anon_memfd_alloc(const char *name, size_t size, void *ptr, int fd) "%s size
%zu ptr %p fd %d"
# memory.c
memory_region_ops_read(int cpu_index, void *mr, uint64_t addr, uint64_t value,
unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"
--
1.8.3.1
