Re: [PATCH] accel/tcg: test CPUJumpCache in tb_jmp_cache_clear_page()

[Eric Auger]

Hi Philippe,
On 2/3/23 18:21, Philippe Mathieu-Daudé wrote:
> On 3/2/23 18:15, Eric Auger wrote:
>> After commit 4e4fa6c12d ("accel/tcg: Complete cpu initialization
>> before registration"), it looks the CPUJumpCache handle can be NULL.
>> This causes a SIGSEV when running debug-wp-migration kvm unit test.
>
> Do you mean commit a976a99a29 ("include/hw/core: Create struct
> CPUJumpCache") instead?
No as reported in
d91ccc02-a963-946d-169a-fd4da2610861@redhat.com/">https://lore.kernel.org/all/d91ccc02-a963-946d-169a-fd4da2610861@redhat.com/
my bisection pointed to 4e4fa6c12d ("accel/tcg: Complete cpu initialization
before registration")
>
>> At the first place it should be clarified why this TCG code is called
>> with KVM acceleration. This may hide another bug.
>>
>> Fixes: 4e4fa6c12d ("accel/tcg: Complete cpu initialization before
>> registration")
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>>   accel/tcg/cputlb.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/accel/tcg/cputlb.c b/accel/tcg/cputlb.c
>> index 4e040a1cb9..ac0245ee6c 100644
>> --- a/accel/tcg/cputlb.c
>> +++ b/accel/tcg/cputlb.c
>> @@ -103,6 +103,10 @@ static void tb_jmp_cache_clear_page(CPUState
>> *cpu, target_ulong page_addr)
>>       int i, i0 = tb_jmp_cache_hash_page(page_addr);
>>       CPUJumpCache *jc = cpu->tb_jmp_cache;
>>   +    if (!jc) {
>
> unlikely()?
yes maybe

Thanks

Eric
>
>> +        return;
>> +    }
>> +
>>       for (i = 0; i < TB_JMP_PAGE_SIZE; i++) {
>>           qatomic_set(&jc->array[i0 + i].tb, NULL);
>>       }
>