Hi
On Wed, Jul 7, 2021 at 9:39 PM Steve Sistare <steven.sist...@oracle.com>
wrote:
> Allocate anonymous memory using memfd_create if the memfd-alloc machine
> option is set.
>
Nice, I'd suggest you send this patch separately. (we had discussions about
an option like this several times)
> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> ---
> hw/core/machine.c | 19 +++++++++++++++++++
> include/hw/boards.h | 1 +
> qemu-options.hx | 5 +++++
> softmmu/physmem.c | 42 +++++++++++++++++++++++++++++++++---------
> trace-events | 1 +
> util/qemu-config.c | 4 ++++
> 6 files changed, 63 insertions(+), 9 deletions(-)
>
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 57c18f9..f0656a8 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -383,6 +383,20 @@ 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);
> @@ -917,6 +931,11 @@ 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 accd6ef..299e1ca 100644
> --- a/include/hw/boards.h
> +++ b/include/hw/boards.h
> @@ -305,6 +305,7 @@ 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 8965dab..fa53734 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
> memory 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 +77,10 @@ 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 memory using
> memfd_create.
> + (disabled by default).
> +
> ``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 9b171c9..b149250 100644
> --- a/softmmu/physmem.c
> +++ b/softmmu/physmem.c
> @@ -64,6 +64,7 @@
>
> #include "qemu/pmem.h"
>
> +#include "qemu/memfd.h"
> #include "migration/vmstate.h"
>
> #include "qemu/range.h"
> @@ -1960,35 +1961,58 @@ 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(new_block->mr);
> + if (ms->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;
>
I wonder if ram_backend_memory_alloc() shouldn't be updated to reflect that
the memory backend is "share" = true. And I would say so in the doc as well.
+ 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/trace-events b/trace-events
> index 765fe25..6dbcd0e 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -40,6 +40,7 @@ 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 84ee6dc..6162b4d 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
>
>
>
--
Marc-André Lureau
