Re: [Qemu-devel] [PATCH v4 18/29] hostmem: add file-based HostMemoryBackend

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 9 Jun 2014 18:25:23 +0800
Hu Tao <hutao@cn.fujitsu.com> wrote:

> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>  backends/Makefile.objs  |   1 +
>  backends/hostmem-file.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 108 insertions(+)
>  create mode 100644 backends/hostmem-file.c
> 
> diff --git a/backends/Makefile.objs b/backends/Makefile.objs
> index 7fb7acd..506a46c 100644
> --- a/backends/Makefile.objs
> +++ b/backends/Makefile.objs
> @@ -8,3 +8,4 @@ baum.o-cflags := $(SDL_CFLAGS)
>  common-obj-$(CONFIG_TPM) += tpm.o
>  
>  common-obj-y += hostmem.o hostmem-ram.o
> +common-obj-$(CONFIG_LINUX) += hostmem-file.o
> diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
> new file mode 100644
> index 0000000..b8df933
> --- /dev/null
> +++ b/backends/hostmem-file.c
> @@ -0,0 +1,107 @@
> +/*
> + * QEMU Host Memory Backend for hugetlbfs
> + *
> + * Copyright (C) 2013 Red Hat Inc
> + *
> + * Authors:
> + *   Paolo Bonzini <pbonzini@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +#include "sysemu/hostmem.h"
> +#include "qom/object_interfaces.h"
> +
> +/* hostmem-file.c */
> +/**
> + * @TYPE_MEMORY_BACKEND_FILE:
> + * name of backend that uses mmap on a file descriptor
> + */
> +#define TYPE_MEMORY_BACKEND_FILE "memory-backend-file"
how about naming it after what it really is? "memory-backend-hugepage"
Later we could split it into generic superclass mmap-ed "memory-backend-file"
and have TPH specific code moved into this backend.

> +
> +#define MEMORY_BACKEND_FILE(obj) \
> +    OBJECT_CHECK(HostMemoryBackendFile, (obj), TYPE_MEMORY_BACKEND_FILE)
> +
> +typedef struct HostMemoryBackendFile HostMemoryBackendFile;
> +
> +struct HostMemoryBackendFile {
> +    HostMemoryBackend parent_obj;
> +    char *mem_path;
> +};
> +
> +static void
> +file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
> +{
> +    HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
> +
> +    if (!backend->size) {
> +        error_setg(errp, "can't create backend with size 0");
> +        return;
> +    }
> +    if (!fb->mem_path) {
> +        error_setg(errp, "mem-path property not set");
> +        return;
> +    }
> +#ifndef CONFIG_LINUX
> +    error_setg(errp, "-mem-path not supported on this host");
Is it possible to not compile this backend on non linux host at all, instead
of ifdefs.

> +#else
> +    if (!memory_region_size(&backend->mr)) {
> +        memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
> +                                 object_get_canonical_path(OBJECT(backend)),
> +                                 backend->size,
> +                                 fb->mem_path, errp);
> +    }
> +#endif
> +}
> +
> +static void
> +file_backend_class_init(ObjectClass *oc, void *data)
> +{
> +    HostMemoryBackendClass *bc = MEMORY_BACKEND_CLASS(oc);
> +
> +    bc->alloc = file_backend_memory_alloc;
> +}
> +
> +static char *get_mem_path(Object *o, Error **errp)
> +{
> +    HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
> +
> +    return g_strdup(fb->mem_path);
> +}
> +
> +static void set_mem_path(Object *o, const char *str, Error **errp)
> +{
> +    HostMemoryBackend *backend = MEMORY_BACKEND(o);
> +    HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o);
> +
> +    if (memory_region_size(&backend->mr)) {
> +        error_setg(errp, "cannot change property value");
> +        return;
> +    }
> +    if (fb->mem_path) {
> +        g_free(fb->mem_path);
> +    }
> +    fb->mem_path = g_strdup(str);
> +}
> +
> +static void
> +file_backend_instance_init(Object *o)
> +{
> +    object_property_add_str(o, "mem-path", get_mem_path,
> +                            set_mem_path, NULL);
s/"mem-path"/"path"/


> +}
> +
> +static const TypeInfo file_backend_info = {
> +    .name = TYPE_MEMORY_BACKEND_FILE,
> +    .parent = TYPE_MEMORY_BACKEND,
> +    .class_init = file_backend_class_init,
> +    .instance_init = file_backend_instance_init,
> +    .instance_size = sizeof(HostMemoryBackendFile),
> +};
> +
> +static void register_types(void)
> +{
> +    type_register_static(&file_backend_info);
> +}
> +
> +type_init(register_types);
> -- 
> 1.9.3
> 


-- 
Regards,
  Igor