Re: [PATCH 0/6] Add various undefined MMIO r/w functions

[P J P]

+-- On Wed, 17 Jun 2020, Paolo Bonzini wrote --+
| On 17/06/20 15:20, Philippe Mathieu-Daudé wrote:
| > On 6/17/20 3:06 PM, Alex Williamson wrote:
| >> On Wed, 17 Jun 2020 16:39:56 +1000
| >> David Gibson <david@gibson.dropbear.id.au> wrote:
| >>> Hrm.  If this is such a common problem, maybe we should just add a NULL 
| >>> check in the common paths.
| >>
| >> +1, clearly the behavior is already expected.  Thanks,
| >
| > 20 months ago Peter suggested:
| > 
| > "assert that every MemoryRegionOps has pointers to callbacks
| >  in it, when it is registered in memory_region_init_io() and
| >  memory_region_init_rom_device_nomigrate()."
| > 
| > https://www.mail-archive.com/qemu-devel@nongnu.org/msg573310.html
| > 
| > Li Qiang refers to this post from Paolo:
| > 
| >>  static const MemoryRegionOps notdirty_mem_ops = {
| >> +    .read = notdirty_mem_read,
| >>      .write = notdirty_mem_write,
| >>      .valid.accepts = notdirty_mem_accepts,
| >>      .endianness = DEVICE_NATIVE_ENDIAN,
| > 
| > "This cannot happen, since TLB_NOTDIRTY is only added
| >  to the addr_write member (see accel/tcg/cputlb.c)."
| 
| I'm now okay with asserting it, as long as notdirty_mem_read abort()s.

Okay, I'm preparing a revised patch.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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