Re: [PATCH v1 1/7] softmmu: fix watchpoint-interrupt races

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> On 11/23/21 9:57 PM, Alex Bennée wrote:
>> From: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
>> Watchpoint may be processed in two phases. First one is detecting
>> the instruction with target memory access. And the second one is
>> executing only one instruction and setting the debug interrupt flag.
>> Hardware interrupts can break this sequence when they happen after
>> the first watchpoint phase.
>> This patch postpones the interrupt request until watchpoint is
>> processed.
>> Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
>> Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
>> Reviewed-by: David Hildenbrand <david@redhat.com>
>> Message-Id: <163662451431.125458.14945698834107669531.stgit@pasha-ThinkPad-X280>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> ---
>>   accel/tcg/cpu-exec.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
>> index 2d14d02f6c..9cb892e326 100644
>> --- a/accel/tcg/cpu-exec.c
>> +++ b/accel/tcg/cpu-exec.c
>> @@ -742,6 +742,11 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
>>               qemu_mutex_unlock_iothread();
>>               return true;
>>           }
>> +        /* Process watchpoints first, or interrupts will ruin everything */
>> +        if (cpu->watchpoint_hit) {
>> +            qemu_mutex_unlock_iothread();
>> +            return false;
>> +        }
>
> I think this is redundant with the next patch.

OK I'll drop it. The function is getting messy anyway.

-- 
Alex Bennée