Hi On Wed, Jul 7, 2021 at 9:39 PM Steve Sistare 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 > --- > 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