Re: [Qemu-stable] [PATCH v2 for-2.11 0/2] Fix TCG atomic writes to nondirty pages

[Peter Maydell]

On 20 November 2017 at 20:54, Paolo Bonzini <address@hidden> wrote:
> On 20/11/2017 19:08, Peter Maydell wrote:
>> To do a write to memory that is marked as notdirty, we need
>> to invalidate any TBs we have cached for that memory, and
>> update the cpu physical memory dirty flags for VGA and migration.
>> The slowpath code in notdirty_mem_write() does all this correctly,
>> but the new atomic handling code in atomic_mmu_lookup() doesn't
>> do anything at all, it just clears the dirty bit in the TLB.
>>
>> The effect of this bug is that if the first write to a notdirty
>> page for which we have cached TBs is by a guest atomic access,
>> we fail to invalidate the TBs and subsequently will execute
>> incorrect code. This can be seen by trying to run 'javac' on AArch64.
>>
>> The first patch here refactors notdirty_mem_write() to pull out
>> the "correctly handle dirty bit updates" parts of the code into
>> two new functions memory_notdirty_write_prepare() and
>> memory_notdirty_write_complete(). The second patch then uses
>> those functions to fix the atomic helpers.
>
> Reviewed-by: Paolo Bonzini <address@hidden>

Thanks; applied to master for rc2.

-- PMM