Re: [PATCH RFC 09/21] ramblock: Add RAM_READONLY

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Peter Xu (peterx@redhat.com) wrote:
> This allows us to have RAM_READONLY to be set in ram_flags to show that
> this ramblock can only be read not write.
> 
> We used to pass in readonly boolean along the way for allocating the
> ramblock, now let it be together with the rest ramblock flags.
> 
> The main purpose of this patch is not for clean up though, it's for caching
> mapping information of each ramblock so when we want to mmap() it again for
> whatever reason we can have all the information on hand.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  backends/hostmem-file.c |  3 ++-
>  include/exec/memory.h   |  4 ++--
>  include/exec/ram_addr.h |  5 ++---
>  softmmu/memory.c        |  8 +++-----
>  softmmu/physmem.c       | 16 +++++++---------
>  5 files changed, 16 insertions(+), 20 deletions(-)
> 
> diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
> index 25141283c4..1daf00d2da 100644
> --- a/backends/hostmem-file.c
> +++ b/backends/hostmem-file.c
> @@ -56,9 +56,10 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
>      ram_flags = backend->share ? RAM_SHARED : 0;
>      ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
>      ram_flags |= fb->is_pmem ? RAM_PMEM : 0;
> +    ram_flags |= fb->readonly ? RAM_READONLY : 0;
>      memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), name,
>                                       backend->size, fb->align, ram_flags,
> -                                     fb->mem_path, fb->readonly, errp);
> +                                     fb->mem_path, errp);
>      g_free(name);
>  #endif
>  }
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index c37ffdbcd1..006ba77ede 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -188,6 +188,8 @@ typedef struct IOMMUTLBEvent {
>  /* RAM is a persistent kind memory */
>  #define RAM_PMEM (1 << 5)
>  
> +/* RAM is read-only */
> +#define RAM_READONLY (1 << 6)
>  
>  /*
>   * UFFDIO_WRITEPROTECT is used on this RAMBlock to
> @@ -1292,7 +1294,6 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr,
>   * @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM,
>   *             RAM_NORESERVE,
>   * @path: the path in which to allocate the RAM.
> - * @readonly: true to open @path for reading, false for read/write.
>   * @errp: pointer to Error*, to store an error if it happens.
>   *
>   * Note that this function does not do anything to cause the data in the
> @@ -1305,7 +1306,6 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
>                                        uint64_t align,
>                                        uint32_t ram_flags,
>                                        const char *path,
> -                                      bool readonly,
>                                        Error **errp);
>  
>  /**
> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> index f4fb6a2111..0bf9cfc659 100644
> --- a/include/exec/ram_addr.h
> +++ b/include/exec/ram_addr.h
> @@ -110,7 +110,6 @@ long qemu_maxrampagesize(void);
>   *  @ram_flags: RamBlock flags. Supported flags: RAM_SHARED, RAM_PMEM,
>   *              RAM_NORESERVE.
>   *  @mem_path or @fd: specify the backing file or device
> - *  @readonly: true to open @path for reading, false for read/write.
>   *  @errp: pointer to Error*, to store an error if it happens
>   *
>   * Return:
> @@ -119,10 +118,10 @@ long qemu_maxrampagesize(void);
>   */
>  RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
>                                     uint32_t ram_flags, const char *mem_path,
> -                                   bool readonly, Error **errp);
> +                                   Error **errp);
>  RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>                                   uint32_t ram_flags, int fd, off_t offset,
> -                                 bool readonly, Error **errp);
> +                                 Error **errp);
>  
>  RAMBlock *qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
>                                    MemoryRegion *mr, Error **errp);
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index e05332d07f..2137028773 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -1601,18 +1601,16 @@ void memory_region_init_ram_from_file(MemoryRegion *mr,
>                                        uint64_t align,
>                                        uint32_t ram_flags,
>                                        const char *path,
> -                                      bool readonly,
>                                        Error **errp)
>  {
>      Error *err = NULL;
>      memory_region_init(mr, owner, name, size);
>      mr->ram = true;
> -    mr->readonly = readonly;
> +    mr->readonly = ram_flags & RAM_READONLY;
>      mr->terminates = true;
>      mr->destructor = memory_region_destructor_ram;
>      mr->align = align;
> -    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path,
> -                                             readonly, &err);
> +    mr->ram_block = qemu_ram_alloc_from_file(size, mr, ram_flags, path, &err);
>      if (err) {
>          mr->size = int128_zero();
>          object_unparent(OBJECT(mr));
> @@ -1635,7 +1633,7 @@ void memory_region_init_ram_from_fd(MemoryRegion *mr,
>      mr->terminates = true;
>      mr->destructor = memory_region_destructor_ram;
>      mr->ram_block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, offset,
> -                                           false, &err);
> +                                           &err);
>      if (err) {
>          mr->size = int128_zero();
>          object_unparent(OBJECT(mr));
> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> index b5be02f1cb..6096eac286 100644
> --- a/softmmu/physmem.c
> +++ b/softmmu/physmem.c
> @@ -1534,7 +1534,6 @@ static int file_ram_open(const char *path,
>  
>  static void *file_ram_alloc(RAMBlock *block,
>                              int fd,
> -                            bool readonly,
>                              bool truncate,
>                              off_t offset,
>                              Error **errp)
> @@ -1589,7 +1588,7 @@ static void *file_ram_alloc(RAMBlock *block,
>          perror("ftruncate");
>      }
>  
> -    qemu_map_flags = readonly ? QEMU_MAP_READONLY : 0;
> +    qemu_map_flags = (block->flags & RAM_READONLY) ? QEMU_MAP_READONLY : 0;
>      qemu_map_flags |= (block->flags & RAM_SHARED) ? QEMU_MAP_SHARED : 0;
>      qemu_map_flags |= (block->flags & RAM_PMEM) ? QEMU_MAP_SYNC : 0;
>      qemu_map_flags |= (block->flags & RAM_NORESERVE) ? QEMU_MAP_NORESERVE : 0;
> @@ -2057,7 +2056,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
>  #ifdef CONFIG_POSIX
>  RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>                                   uint32_t ram_flags, int fd, off_t offset,
> -                                 bool readonly, Error **errp)
> +                                 Error **errp)
>  {
>      RAMBlock *new_block;
>      Error *local_err = NULL;
> @@ -2065,7 +2064,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>  
>      /* Just support these ram flags by now. */
>      assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
> -                          RAM_PROTECTED)) == 0);
> +                          RAM_PROTECTED | RAM_READONLY)) == 0);
>  
>      if (xen_enabled()) {
>          error_setg(errp, "-mem-path not supported with Xen");
> @@ -2100,8 +2099,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>      new_block->used_length = size;
>      new_block->max_length = size;
>      new_block->flags = ram_flags;
> -    new_block->host = file_ram_alloc(new_block, fd, readonly,
> -                                     !file_size, offset, errp);
> +    new_block->host = file_ram_alloc(new_block, fd, !file_size, offset, errp);
>      if (!new_block->host) {
>          g_free(new_block);
>          return NULL;
> @@ -2120,11 +2118,11 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
>  
>  RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
>                                     uint32_t ram_flags, const char *mem_path,
> -                                   bool readonly, Error **errp)
> +                                   Error **errp)
>  {
>      int fd;
> -    bool created;
>      RAMBlock *block;
> +    bool created, readonly = ram_flags & RAM_READONLY;
>  
>      fd = file_ram_open(mem_path, memory_region_name(mr), readonly, &created,
>                         errp);
> @@ -2132,7 +2130,7 @@ RAMBlock *qemu_ram_alloc_from_file(ram_addr_t size, MemoryRegion *mr,
>          return NULL;
>      }
>  
> -    block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, 0, readonly, errp);
> +    block = qemu_ram_alloc_from_fd(size, mr, ram_flags, fd, 0, errp);
>      if (!block) {
>          if (created) {
>              unlink(mem_path);
> -- 
> 2.37.3
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK