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From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
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Date: Mon, 20 Mar 2017 16:16:20 +0000
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Subject: Re: [Qemu-devel] [PATCH v1 1/3] cputlb: ensure tbl_set_dirty1
 updates addr_write atomically
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: peter.maydell@linaro.org, rth@twiddle.net, qemu-devel@nongnu.org, mttcg@listserver.greensocs.com, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, cota@braap.org, bobby.prani@gmail.com, nikunj@linux.vnet.ibm.com, Peter Crosthwaite <crosthwaite.peter@gmail.com>


Paolo Bonzini <pbonzini@redhat.com> writes:

> On 20/03/2017 16:34, Alex Bennée wrote:
>>  static inline void tlb_set_dirty1(CPUTLBEntry *tlb_entry, target_ulong vaddr)
>>  {
>> +#if TCG_OVERSIZED_GUEST
>>      if (tlb_entry->addr_write == (vaddr | TLB_NOTDIRTY)) {
>>          tlb_entry->addr_write = vaddr;
>>      }
>> +#else
>> +    uintptr_t orig_addr = atomic_mb_read(&tlb_entry->addr_write);
>
> atomic_read is enough, since we don't care at all about cases where the
> address doesn't match.  Otherwise

Good catch. Will fix for my pullreq

>
> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
>
> Paolo
>
>> +    if (orig_addr == (vaddr | TLB_NOTDIRTY)) {
>> +        atomic_cmpxchg(&tlb_entry->addr_write, orig_addr, vaddr);
>> +    }
>> +#endif
>>  }


--
Alex Bennée