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Re: [Qemu-devel] [PATCH] exec: revert MemoryRegionCache


From: Paolo Bonzini
Subject: Re: [Qemu-devel] [PATCH] exec: revert MemoryRegionCache
Date: Mon, 3 Apr 2017 18:46:56 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0


On 03/04/2017 18:15, Michael S. Tsirkin wrote:
> On Mon, Apr 03, 2017 at 03:39:01PM +0200, Paolo Bonzini wrote:
>> MemoryRegionCache did not know about virtio support for IOMMUs (because the
>> two features were developed at the same time).  Revert MemoryRegionCache
>> to "normal" address_space_* operations for 2.9, as it is simpler than
>> undoing the virtio patches.
>>
>> Signed-off-by: Paolo Bonzini <address@hidden>
> 
> Reviewed-by: Michael S. Tsirkin <address@hidden>
> 
> who's merging this? Me?

I will send a pull request in a few hours.

Paolo

>> ---
>>  exec.c                | 64 
>> +++++++++------------------------------------------
>>  include/exec/memory.h | 10 ++++----
>>  2 files changed, 15 insertions(+), 59 deletions(-)
>>
>> diff --git a/exec.c b/exec.c
>> index e57a8a2..c97ef4a 100644
>> --- a/exec.c
>> +++ b/exec.c
>> @@ -3236,75 +3236,33 @@ int64_t address_space_cache_init(MemoryRegionCache 
>> *cache,
>>                                   hwaddr len,
>>                                   bool is_write)
>>  {
>> -    hwaddr l, xlat;
>> -    MemoryRegion *mr;
>> -    void *ptr;
>> -
>> -    assert(len > 0);
>> -
>> -    l = len;
>> -    mr = address_space_translate(as, addr, &xlat, &l, is_write);
>> -    if (!memory_access_is_direct(mr, is_write)) {
>> -        return -EINVAL;
>> -    }
>> -
>> -    l = address_space_extend_translation(as, addr, len, mr, xlat, l, 
>> is_write);
>> -    ptr = qemu_ram_ptr_length(mr->ram_block, xlat, &l);
>> -
>> -    cache->xlat = xlat;
>> -    cache->is_write = is_write;
>> -    cache->mr = mr;
>> -    cache->ptr = ptr;
>> -    cache->len = l;
>> -    memory_region_ref(cache->mr);
>> -
>> -    return l;
>> +    cache->len = len;
>> +    cache->as = as;
>> +    cache->xlat = addr;
>> +    return len;
>>  }
>>  
>>  void address_space_cache_invalidate(MemoryRegionCache *cache,
>>                                      hwaddr addr,
>>                                      hwaddr access_len)
>>  {
>> -    assert(cache->is_write);
>> -    invalidate_and_set_dirty(cache->mr, addr + cache->xlat, access_len);
>>  }
>>  
>>  void address_space_cache_destroy(MemoryRegionCache *cache)
>>  {
>> -    if (!cache->mr) {
>> -        return;
>> -    }
>> -
>> -    if (xen_enabled()) {
>> -        xen_invalidate_map_cache_entry(cache->ptr);
>> -    }
>> -    memory_region_unref(cache->mr);
>> -    cache->mr = NULL;
>> -}
>> -
>> -/* Called from RCU critical section.  This function has the same
>> - * semantics as address_space_translate, but it only works on a
>> - * predefined range of a MemoryRegion that was mapped with
>> - * address_space_cache_init.
>> - */
>> -static inline MemoryRegion *address_space_translate_cached(
>> -    MemoryRegionCache *cache, hwaddr addr, hwaddr *xlat,
>> -    hwaddr *plen, bool is_write)
>> -{
>> -    assert(addr < cache->len && *plen <= cache->len - addr);
>> -    *xlat = addr + cache->xlat;
>> -    return cache->mr;
>> +    cache->as = NULL;
>>  }
>>  
>>  #define ARG1_DECL                MemoryRegionCache *cache
>>  #define ARG1                     cache
>>  #define SUFFIX                   _cached
>> -#define TRANSLATE(...)           address_space_translate_cached(cache, 
>> __VA_ARGS__)
>> +#define TRANSLATE(addr, ...)     \
>> +    address_space_translate(cache->as, cache->xlat + (addr), __VA_ARGS__)
>>  #define IS_DIRECT(mr, is_write)  true
>> -#define MAP_RAM(mr, ofs)         (cache->ptr + (ofs - cache->xlat))
>> -#define INVALIDATE(mr, ofs, len) ((void)0)
>> -#define RCU_READ_LOCK()          ((void)0)
>> -#define RCU_READ_UNLOCK()        ((void)0)
>> +#define MAP_RAM(mr, ofs)         qemu_map_ram_ptr((mr)->ram_block, ofs)
>> +#define INVALIDATE(mr, ofs, len) invalidate_and_set_dirty(mr, ofs, len)
>> +#define RCU_READ_LOCK()          rcu_read_lock()
>> +#define RCU_READ_UNLOCK()        rcu_read_unlock()
>>  #include "memory_ldst.inc.c"
>>  
>>  /* virtual memory access for debug (includes writing to ROM) */
>> diff --git a/include/exec/memory.h b/include/exec/memory.h
>> index e39256a..f20b191 100644
>> --- a/include/exec/memory.h
>> +++ b/include/exec/memory.h
>> @@ -1426,13 +1426,11 @@ void stq_be_phys(AddressSpace *as, hwaddr addr, 
>> uint64_t val);
>>  
>>  struct MemoryRegionCache {
>>      hwaddr xlat;
>> -    void *ptr;
>>      hwaddr len;
>> -    MemoryRegion *mr;
>> -    bool is_write;
>> +    AddressSpace *as;
>>  };
>>  
>> -#define MEMORY_REGION_CACHE_INVALID ((MemoryRegionCache) { .mr = NULL })
>> +#define MEMORY_REGION_CACHE_INVALID ((MemoryRegionCache) { .as = NULL })
>>  
>>  /* address_space_cache_init: prepare for repeated access to a physical
>>   * memory region
>> @@ -1688,7 +1686,7 @@ address_space_read_cached(MemoryRegionCache *cache, 
>> hwaddr addr,
>>                            void *buf, int len)
>>  {
>>      assert(addr < cache->len && len <= cache->len - addr);
>> -    memcpy(buf, cache->ptr + addr, len);
>> +    address_space_read(cache->as, cache->xlat + addr, 
>> MEMTXATTRS_UNSPECIFIED, buf, len);
>>  }
>>  
>>  /**
>> @@ -1704,7 +1702,7 @@ address_space_write_cached(MemoryRegionCache *cache, 
>> hwaddr addr,
>>                             void *buf, int len)
>>  {
>>      assert(addr < cache->len && len <= cache->len - addr);
>> -    memcpy(cache->ptr + addr, buf, len);
>> +    address_space_write(cache->as, cache->xlat + addr, 
>> MEMTXATTRS_UNSPECIFIED, buf, len);
>>  }
>>  
>>  #endif
>> -- 
>> 2.9.3
> 



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