Allocate anonymous memory using memfd_create if the memfd-alloc machine
option is set.
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
hw/core/machine.c | 19 +++++++++++++++++++
include/hw/boards.h | 1 +
qemu-options.hx | 6 ++++++
softmmu/physmem.c | 47 ++++++++++++++++++++++++++++++++++++++---------
softmmu/vl.c | 1 +
trace-events | 1 +
util/qemu-config.c | 4 ++++
7 files changed, 70 insertions(+), 9 deletions(-)
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 53a99ab..7739d88 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -392,6 +392,20 @@ static void machine_set_mem_merge(Object *obj, bool value,
Error **errp)
ms->mem_merge = value;
}
+static bool machine_get_memfd_alloc(Object *obj, Error **errp)
+{
+ MachineState *ms = MACHINE(obj);
+
+ return ms->memfd_alloc;
+}
+
+static void machine_set_memfd_alloc(Object *obj, bool value, Error **errp)
+{
+ MachineState *ms = MACHINE(obj);
+
+ ms->memfd_alloc = value;
+}
+
static bool machine_get_usb(Object *obj, Error **errp)
{
MachineState *ms = MACHINE(obj);
@@ -829,6 +843,11 @@ static void machine_class_init(ObjectClass *oc, void *data)
object_class_property_set_description(oc, "mem-merge",
"Enable/disable memory merge support");
+ object_class_property_add_bool(oc, "memfd-alloc",
+ machine_get_memfd_alloc, machine_set_memfd_alloc);
+ object_class_property_set_description(oc, "memfd-alloc",
+ "Enable/disable allocating anonymous memory using memfd_create");
+
object_class_property_add_bool(oc, "usb",
machine_get_usb, machine_set_usb);
object_class_property_set_description(oc, "usb",
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 9c1c190..a57d7a0 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -327,6 +327,7 @@ struct MachineState {
char *dt_compatible;
bool dump_guest_core;
bool mem_merge;
+ bool memfd_alloc;
bool usb;
bool usb_disabled;
char *firmware;
diff --git a/qemu-options.hx b/qemu-options.hx
index 7d47510..33c8173 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -30,6 +30,7 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
" vmport=on|off|auto controls emulation of vmport (default:
auto)\n"
" dump-guest-core=on|off include guest memory in a core
dump (default=on)\n"
" mem-merge=on|off controls memory merge support (default:
on)\n"
+ " memfd-alloc=on|off controls allocating anonymous guest
RAM using memfd_create (default: off)\n"
" aes-key-wrap=on|off controls support for AES key wrapping
(default=on)\n"
" dea-key-wrap=on|off controls support for DEA key wrapping
(default=on)\n"
" suppress-vmdesc=on|off disables self-describing migration
(default=off)\n"
@@ -76,6 +77,11 @@ SRST
supported by the host, de-duplicates identical memory pages
among VMs instances (enabled by default).
+ ``memfd-alloc=on|off``
+ Enables or disables allocation of anonymous guest RAM using
+ memfd_create. Any associated memory-backend objects are created with
+ share=on. The memfd-alloc default is off.
+
``aes-key-wrap=on|off``
Enables or disables AES key wrapping support on s390-ccw hosts.
This feature controls whether AES wrapping keys will be created
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 3524c04..95e2b49 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -41,6 +41,7 @@
#include "qemu/config-file.h"
#include "qemu/error-report.h"
#include "qemu/qemu-print.h"
+#include "qemu/memfd.h"
#include "exec/memory.h"
#include "exec/ioport.h"
#include "sysemu/dma.h"
@@ -1964,35 +1965,63 @@ static void ram_block_add(RAMBlock *new_block, Error
**errp)
const bool shared = qemu_ram_is_shared(new_block);
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;
+ MachineState *ms = MACHINE(qdev_get_machine());
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 = qemu_anon_ram_alloc(new_block->max_length,
- &new_block->mr->align,
- shared, noreserve);
- if (!new_block->host) {
+ name = memory_region_name(mr);
+ if (ms->memfd_alloc) {
+ Object *parent = &mr->parent_obj;
+ 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;
+ }
+ }
+ qemu_set_cloexec(mfd);
+ /* The memory backend already set its desired flags. */
+ if (!object_dynamic_cast(parent, TYPE_MEMORY_BACKEND)) {
+ new_block->flags |= RAM_SHARED;
+ }
+ addr = file_ram_alloc(new_block, maxlen, mfd,
+ false, false, 0, errp);
+ trace_anon_memfd_alloc(name, maxlen, addr, mfd);
+ } else {
+ addr = qemu_anon_ram_alloc(maxlen, &mr->align,
+ shared, noreserve);
+ }
+
+ 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/softmmu/vl.c b/softmmu/vl.c
index 620a1f1..ab3648a 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2440,6 +2440,7 @@ static void create_default_memdev(MachineState *ms, const
char *path)
object_property_set_str(obj, "mem-path", path, &error_fatal);
}
object_property_set_int(obj, "size", ms->ram_size, &error_fatal);
+ object_property_set_bool(obj, "share", ms->memfd_alloc, &error_fatal);
object_property_add_child(object_get_objects_root(), mc->default_ram_id,
obj);
/* Ensure backend's memory region name is equal to mc->default_ram_id */
diff --git a/trace-events b/trace-events
index a637a61..770a9ac 100644
--- a/trace-events
+++ b/trace-events
@@ -45,6 +45,7 @@ ram_block_discard_range(const char *rbname, void *hva, size_t
length, bool need_
# accel/tcg/cputlb.c
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"
# gdbstub.c
gdbstub_op_start(const char *device) "Starting gdbstub using device %s"
diff --git a/util/qemu-config.c b/util/qemu-config.c
index 436ab63..3606e5c 100644
--- a/util/qemu-config.c
+++ b/util/qemu-config.c
@@ -207,6 +207,10 @@ static QemuOptsList machine_opts = {
.type = QEMU_OPT_BOOL,
.help = "enable/disable memory merge support",
},{
+ .name = "memfd-alloc",
+ .type = QEMU_OPT_BOOL,
+ .help = "enable/disable memfd_create for anonymous memory",
+ },{
.name = "usb",
.type = QEMU_OPT_BOOL,
.help = "Set on/off to enable/disable usb",
--
1.8.3.1
