[Xen-devel] Re: [Qemu-devel] [PATCH RFC V3 08/12] Intruduce qemu_ram_ptr_unlock.

[Blue Swirl <blauwirbel@xxxxxxxxx>]

On Fri, Sep 17, 2010 at 11:15 AM,  <anthony.perard@xxxxxxxxxx> wrote:
> From: Anthony PERARD <anthony.perard@xxxxxxxxxx>
>
> This function allows to unlock a ram_ptr give by qemu_get_ram_ptr. After
> a call to qemu_ram_ptr_unlock, the pointer may be unmap from QEMU when
> used with Xen.
>
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> ---
>  cpu-common.h   |    1 +
>  exec.c         |   29 ++++++++++++++++++++++++++---
>  xen_mapcache.c |   34 ++++++++++++++++++++++++++++++++++
>  xen_mapcache.h |    1 +
>  4 files changed, 62 insertions(+), 3 deletions(-)
>
> diff --git a/cpu-common.h b/cpu-common.h
> index 0426bc8..378eea8 100644
> --- a/cpu-common.h
> +++ b/cpu-common.h
> @@ -46,6 +46,7 @@ ram_addr_t qemu_ram_alloc(DeviceState *dev, const char 
> *name, ram_addr_t size);
>  void qemu_ram_free(ram_addr_t addr);
>  /* This should only be used for ram local to a device.  */
>  void *qemu_get_ram_ptr(ram_addr_t addr);
> +void qemu_ram_ptr_unlock(void *addr);
>  /* This should not be used by devices.  */
>  ram_addr_t qemu_ram_addr_from_host(void *ptr);
>
> diff --git a/exec.c b/exec.c
> index f5888eb..659db50 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2959,6 +2959,13 @@ void *qemu_get_ram_ptr(ram_addr_t addr)
>     return NULL;
>  }
>
> +void qemu_ram_ptr_unlock(void *addr)
> +{
> +    if (xen_enabled()) {
> +        qemu_map_cache_unlock(addr);

I think there may be linkage problems without CONFIG_XEN, so there
should be a stub for qemu_map_cache_unlock().

> +    }
> +}
> +
>  /* Some of the softmmu routines need to translate from a host pointer
>    (typically a TLB entry) back to a ram offset.  */
>  ram_addr_t qemu_ram_addr_from_host(void *ptr)
> @@ -3064,6 +3071,7 @@ static void notdirty_mem_writeb(void *opaque, 
> target_phys_addr_t ram_addr,
>                                 uint32_t val)
>  {
>     int dirty_flags;
> +    void *vaddr;
>     dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>     if (!(dirty_flags & CODE_DIRTY_FLAG)) {
>  #if !defined(CONFIG_USER_ONLY)
> @@ -3071,19 +3079,21 @@ static void notdirty_mem_writeb(void *opaque, 
> target_phys_addr_t ram_addr,
>         dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
>  #endif
>     }
> -    stb_p(qemu_get_ram_ptr(ram_addr), val);
> +    stb_p(vaddr = qemu_get_ram_ptr(ram_addr), val);

Perhaps 'vaddr = ...'  should be put on a separate line.

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