Re: [Qemu-devel] [PATCH 2/2] memory: hide mr->ram_addr from qemu_get_ram_ptr users

[Paolo Bonzini <pbonzini@redhat.com>]

----- Original Message -----
> From: "Fam Zheng" <famz@redhat.com>
> To: "Paolo Bonzini" <pbonzini@redhat.com>
> Cc: qemu-devel@nongnu.org, "arei gonglei" <arei.gonglei@huawei.com>, mst@redhat.com
> Sent: Friday, March 25, 2016 7:20:38 AM
> Subject: Re: [PATCH 2/2] memory: hide mr->ram_addr from qemu_get_ram_ptr users
> 
> On Thu, 03/24 12:03, Paolo Bonzini wrote:
> > Let users of qemu_get_ram_ptr and qemu_ram_ptr_length pass in an
> > address that is relative to the MemoryRegion.  This basically means
> > what address_space_translate returns.
> > 
> > invalidate_and_set_dirty has to add back mr->ram_addr, but reads do
> > not need it at all.
> > 
> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> > ---
> >  exec.c                       | 40 +++++++++++++++-------------------------
> >  include/exec/memory.h        |  1 -
> >  memory.c                     |  4 ++--
> >  scripts/dump-guest-memory.py | 19 +++----------------
> >  4 files changed, 20 insertions(+), 44 deletions(-)
> > 
> > diff --git a/exec.c b/exec.c
> > index 001b669..ca9e3b6 100644
> > --- a/exec.c
> > +++ b/exec.c
> > @@ -1876,6 +1876,7 @@ void *qemu_get_ram_ptr(RAMBlock *ram_block,
> > ram_addr_t addr)
> 
> Shall we rename the parameter to "offset" then?  I don't know, but that seems
> easier to read for me.

Good question.  I'm not sure about that because of the block == NULL case,
where the address is absolute.

> > @@ -1924,7 +1924,7 @@ static void *qemu_ram_ptr_length(RAMBlock *ram_block,
> > ram_addr_t addr,
> >          block->host = xen_map_cache(block->offset, block->max_length, 1);
> >      }
> >  
> > -    return ramblock_ptr(block, offset_inside_block);
> > +    return ramblock_ptr(block, addr);
> >  }
> >  
> >  /*
> > @@ -2504,6 +2504,8 @@ static void invalidate_and_set_dirty(MemoryRegion
> > *mr, hwaddr addr,
> >                                       hwaddr length)
> >  {
> >      uint8_t dirty_log_mask = memory_region_get_dirty_log_mask(mr);
> > +    addr += memory_region_get_ram_addr(mr);
> > +
> 
> If called by address_space_unmap, is this addition still correct?

No, thanks for the careful review!  That's another opportunity
for cleanup actually, splitting the (few) users of qemu_ram_addr_from_host
that really need a ram_addr_t and those (the majority) that need a
MemoryRegion and offset.  They can use two different functions.  I'll
defer this to 2.7 and post the patches to do so later.

> > @@ -3382,13 +3374,13 @@ void address_space_stl_notdirty(AddressSpace *as,
> > hwaddr addr, uint32_t val,
> >  
> >          r = memory_region_dispatch_write(mr, addr1, val, 4, attrs);
> >      } else {
> > -        addr1 += memory_region_get_ram_addr(mr);
> >          ptr = qemu_get_ram_ptr(mr->ram_block, addr1);
> >          stl_p(ptr, val);
> >  
> >          dirty_log_mask = memory_region_get_dirty_log_mask(mr);
> >          dirty_log_mask &= ~(1 << DIRTY_MEMORY_CODE);
> > -        cpu_physical_memory_set_dirty_range(addr1, 4, dirty_log_mask);
> > +        cpu_physical_memory_set_dirty_range(memory_region_get_ram_addr(mr)
> > + addr,
> 
> Is this line too long?

It's 82 characters

Paolo