Re: [Qemu-devel] [PATCH 1/4] memory: remove qemu_get_ram_fd, qemu_set_ram_fd, qemu_ram_block_host_ptr

[Marc-André Lureau]

Hi

On Thu, May 26, 2016 at 10:49 AM, Paolo Bonzini <address@hidden> wrote:
> Remove direct uses of ram_addr_t and optimize memory_region_{get,set}_fd
> now that a MemoryRegion knows its RAMBlock directly.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  exec.c                  | 34 ----------------------------------
>  hw/misc/ivshmem.c       |  5 ++---
>  hw/virtio/vhost-user.c  | 15 +++++++--------
>  include/exec/memory.h   | 11 +++++++++++
>  include/exec/ram_addr.h |  3 ---
>  memory.c                | 21 +++++++++++++++++----
>  6 files changed, 37 insertions(+), 52 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index a3a93ae..3330e7d 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1815,40 +1815,6 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length)
>  }
>  #endif /* !_WIN32 */
>
> -int qemu_get_ram_fd(ram_addr_t addr)
> -{
> -    RAMBlock *block;
> -    int fd;
> -
> -    rcu_read_lock();
> -    block = qemu_get_ram_block(addr);
> -    fd = block->fd;
> -    rcu_read_unlock();
> -    return fd;
> -}
> -
> -void qemu_set_ram_fd(ram_addr_t addr, int fd)
> -{
> -    RAMBlock *block;
> -
> -    rcu_read_lock();
> -    block = qemu_get_ram_block(addr);
> -    block->fd = fd;
> -    rcu_read_unlock();
> -}
> -
> -void *qemu_get_ram_block_host_ptr(ram_addr_t addr)
> -{
> -    RAMBlock *block;
> -    void *ptr;
> -
> -    rcu_read_lock();
> -    block = qemu_get_ram_block(addr);
> -    ptr = ramblock_ptr(block, 0);
> -    rcu_read_unlock();
> -    return ptr;
> -}
> -
>  /* Return a host pointer to ram allocated with qemu_ram_alloc.
>   * This should not be used for general purpose DMA.  Use address_space_map
>   * or address_space_rw instead. For local memory (e.g. video ram) that the
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index e40f23b..90be9f7 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -33,7 +33,6 @@
>  #include "sysemu/hostmem.h"
>  #include "sysemu/qtest.h"
>  #include "qapi/visitor.h"
> -#include "exec/ram_addr.h"
>
>  #include "hw/misc/ivshmem.h"
>
> @@ -533,7 +532,7 @@ static void process_msg_shmem(IVShmemState *s, int fd, 
> Error **errp)
>      }
>      memory_region_init_ram_ptr(&s->server_bar2, OBJECT(s),
>                                 "ivshmem.bar2", size, ptr);
> -    qemu_set_ram_fd(memory_region_get_ram_addr(&s->server_bar2), fd);
> +    memory_region_set_fd(&s->server_bar2, fd);
>      s->ivshmem_bar2 = &s->server_bar2;
>  }
>
> @@ -940,7 +939,7 @@ static void ivshmem_exit(PCIDevice *dev)
>                               strerror(errno));
>              }
>
> -            fd = 
> qemu_get_ram_fd(memory_region_get_ram_addr(s->ivshmem_bar2));
> +            fd = memory_region_get_fd(s->ivshmem_bar2);
>              close(fd);
>          }
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 5914e85..41908c0 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -248,17 +248,18 @@ static int vhost_user_set_mem_table(struct vhost_dev 
> *dev,
>      for (i = 0; i < dev->mem->nregions; ++i) {
>          struct vhost_memory_region *reg = dev->mem->regions + i;
>          ram_addr_t ram_addr;
> +        MemoryRegion *mr;
>
>          assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
> -        qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr,
> -                                &ram_addr);
> -        fd = qemu_get_ram_fd(ram_addr);
> +        mr = qemu_ram_addr_from_host((void *)(uintptr_t)reg->userspace_addr,
> +                                     &ram_addr);
> +        fd = memory_region_get_fd(mr);
>          if (fd > 0) {
>              msg.payload.memory.regions[fd_num].userspace_addr = 
> reg->userspace_addr;
>              msg.payload.memory.regions[fd_num].memory_size  = 
> reg->memory_size;
>              msg.payload.memory.regions[fd_num].guest_phys_addr = 
> reg->guest_phys_addr;
>              msg.payload.memory.regions[fd_num].mmap_offset = 
> reg->userspace_addr -
> -                (uintptr_t) qemu_get_ram_block_host_ptr(ram_addr);
> +                (uintptr_t) memory_region_get_ram_ptr(mr);
>              assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
>              fds[fd_num++] = fd;
>          }
> @@ -621,12 +622,10 @@ static bool vhost_user_can_merge(struct vhost_dev *dev,
>      MemoryRegion *mr;
>
>      mr = qemu_ram_addr_from_host((void *)(uintptr_t)start1, &ram_addr);
> -    assert(mr);
> -    mfd = qemu_get_ram_fd(ram_addr);
> +    mfd = memory_region_get_fd(mr);
>
>      mr = qemu_ram_addr_from_host((void *)(uintptr_t)start2, &ram_addr);
> -    assert(mr);
> -    rfd = qemu_get_ram_fd(ram_addr);
> +    rfd = memory_region_get_fd(mr);
>

You get rid of a few assert in the patch, any particular reason?

>      return mfd == rfd;
>  }
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index f649697..1678494 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -667,6 +667,17 @@ static inline bool memory_region_is_rom(MemoryRegion *mr)
>  int memory_region_get_fd(MemoryRegion *mr);
>
>  /**
> + * memory_region_set_fd: Mark a RAM memory region as backed by a
> + * file descriptor.
> + *
> + * This function is typically used after memory_region_init_ram_ptr().
> + *
> + * @mr: the memory region being queried.

...being updated

> + * @fd: the file descriptor that backs @mr.
> + */
> +void memory_region_set_fd(MemoryRegion *mr, int fd);
> +
> +/**
>   * memory_region_get_ram_ptr: Get a pointer into a RAM memory region.
>   *
>   * Returns a host pointer to a RAM memory region (created with
> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> index 5b6e1b8..2a9465d 100644
> --- a/include/exec/ram_addr.h
> +++ b/include/exec/ram_addr.h
> @@ -105,9 +105,6 @@ RAMBlock *qemu_ram_alloc_resizeable(ram_addr_t size, 
> ram_addr_t max_size,
>                                                      uint64_t length,
>                                                      void *host),
>                                      MemoryRegion *mr, Error **errp);
> -int qemu_get_ram_fd(ram_addr_t addr);
> -void qemu_set_ram_fd(ram_addr_t addr, int fd);
> -void *qemu_get_ram_block_host_ptr(ram_addr_t addr);
>  void qemu_ram_free(RAMBlock *block);
>
>  int qemu_ram_resize(RAMBlock *block, ram_addr_t newsize, Error **errp);
> diff --git a/memory.c b/memory.c
> index 0f52522..d6a4a68 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1626,13 +1626,26 @@ void memory_region_reset_dirty(MemoryRegion *mr, 
> hwaddr addr,
>
>  int memory_region_get_fd(MemoryRegion *mr)
>  {
> -    if (mr->alias) {
> -        return memory_region_get_fd(mr->alias);
> +    int fd;
> +
> +    rcu_read_lock();
> +    while (mr->alias) {
> +        mr = mr->alias;
>      }
> +    fd = mr->ram_block->fd;
> +    rcu_read_unlock();
>
> -    assert(mr->ram_block);
> +    return fd;
> +}
>
> -    return qemu_get_ram_fd(memory_region_get_ram_addr(mr));
> +void memory_region_set_fd(MemoryRegion *mr, int fd)
> +{
> +    rcu_read_lock();
> +    while (mr->alias) {
> +        mr = mr->alias;
> +    }
> +    mr->ram_block->fd = fd;
> +    rcu_read_unlock();
>  }
>
>  void *memory_region_get_ram_ptr(MemoryRegion *mr)
> --
> 2.5.5
>
>
>

Reviewed-by: Marc-André Lureau <address@hidden>




-- 
Marc-André Lureau