[Xen-devel] Re: [Qemu-devel] [PATCH V9 12/16] Introduce qemu_ram_ptr_unlock.

[Anthony Liguori <anthony@xxxxxxxxxxxxx>]

On 01/25/2011 08:29 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         |   10 ++++++++++
>   xen-mapcache.c |   34 ++++++++++++++++++++++++++++++++++
>   3 files changed, 45 insertions(+), 0 deletions(-)
>
> diff --git a/cpu-common.h b/cpu-common.h
> index 6d4a898..8fa6d80 100644
> --- a/cpu-common.h
> +++ b/cpu-common.h
> @@ -55,6 +55,7 @@ void *qemu_get_ram_ptr(ram_addr_t addr);
>   /* Same but slower, to use for migration, where the order of
>    * RAMBlocks must not change. */
>   void *qemu_safe_ram_ptr(ram_addr_t addr);
> +void qemu_ram_ptr_unlock(void *addr);
>   /* This should not be used by devices.  */
>   int qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr);
>   ram_addr_t qemu_ram_addr_from_host_nofail(void *ptr);
> diff --git a/exec.c b/exec.c
> index 3b137dc..8acf2a9 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2977,6 +2977,13 @@ void *qemu_safe_ram_ptr(ram_addr_t addr)
>       return NULL;
>   }
>
> +void qemu_ram_ptr_unlock(void *addr)
> +{
> +    if (xen_mapcache_enabled()) {
> +        qemu_map_cache_unlock(addr);
> +    }
> +}
> +
>    
qemu_put_ram_ptr() would be a better name.

Regards,

Anthony Liguori

>   int qemu_ram_addr_from_host(void *ptr, ram_addr_t *ram_addr)
>   {
>       RAMBlock *block;
> @@ -3692,6 +3699,7 @@ void cpu_physical_memory_rw(target_phys_addr_t addr, 
> uint8_t *buf,
>                       cpu_physical_memory_set_dirty_flags(
>                           addr1, (0xff&  ~CODE_DIRTY_FLAG));
>                   }
> +                qemu_ram_ptr_unlock(ptr);
>               }
>           } else {
>               if ((pd&  ~TARGET_PAGE_MASK)>  IO_MEM_ROM&&
> @@ -3722,6 +3730,7 @@ void cpu_physical_memory_rw(target_phys_addr_t addr, 
> uint8_t *buf,
>                   ptr = qemu_get_ram_ptr(pd&  TARGET_PAGE_MASK) +
>                       (addr&  ~TARGET_PAGE_MASK);
>                   memcpy(buf, ptr, l);
> +                qemu_ram_ptr_unlock(ptr);
>               }
>           }
>           len -= l;
> @@ -3762,6 +3771,7 @@ void cpu_physical_memory_write_rom(target_phys_addr_t 
> addr,
>               /* ROM/RAM case */
>               ptr = qemu_get_ram_ptr(addr1);
>               memcpy(ptr, buf, l);
> +            qemu_ram_ptr_unlock(ptr);
>           }
>           len -= l;
>           buf += l;
> diff --git a/xen-mapcache.c b/xen-mapcache.c
> index 3e1cca9..23a23f9 100644
> --- a/xen-mapcache.c
> +++ b/xen-mapcache.c
> @@ -187,6 +187,40 @@ uint8_t *qemu_map_cache(target_phys_addr_t phys_addr, 
> target_phys_addr_t size, u
>       return mapcache->last_address_vaddr + address_offset;
>   }
>
> +void qemu_map_cache_unlock(void *buffer)
> +{
> +    MapCacheEntry *entry = NULL, *pentry = NULL;
> +    MapCacheRev *reventry;
> +    target_phys_addr_t paddr_index;
> +    int found = 0;
> +
> +    QTAILQ_FOREACH(reventry,&mapcache->locked_entries, next) {
> +        if (reventry->vaddr_req == buffer) {
> +            paddr_index = reventry->paddr_index;
> +            found = 1;
> +            break;
> +        }
> +    }
> +    if (!found) {
> +        return;
> +    }
> +    QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
> +    qemu_free(reventry);
> +
> +    entry =&mapcache->entry[paddr_index % mapcache->nr_buckets];
> +    while (entry&&  entry->paddr_index != paddr_index) {
> +        pentry = entry;
> +        entry = entry->next;
> +    }
> +    if (!entry) {
> +        return;
> +    }
> +    entry->lock--;
> +    if (entry->lock>  0) {
> +        entry->lock--;
> +    }
> +}
> +
>   ram_addr_t qemu_ram_addr_from_mapcache(void *ptr)
>   {
>       MapCacheRev *reventry;
>    

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