Re: [PATCH v3 04/13] irqchip: GICv3: ITS command queue
From: Marc Zyngier
Date: Wed Dec 10 2014 - 06:20:58 EST
On 10/12/14 03:03, Yun Wu (Abel) wrote:
> On 2014/11/24 22:35, Marc Zyngier wrote:
>> +static struct its_collection *its_build_mapd_cmd(struct its_cmd_block *cmd,
>> + struct its_cmd_desc *desc)
>> + unsigned long itt_addr;
>> + u8 size = order_base_2(desc->its_mapd_cmd.dev->nr_ites);
> If @nr_ites is 1, then @size becomes 0, and... (see below)
>> + itt_addr = virt_to_phys(desc->its_mapd_cmd.dev->itt);
>> + itt_addr = ALIGN(itt_addr, ITS_ITT_ALIGN);
>> + its_encode_cmd(cmd, GITS_CMD_MAPD);
>> + its_encode_devid(cmd, desc->its_mapd_cmd.dev->device_id);
>> + its_encode_size(cmd, size - 1);
> here (size - 1) becomes the value of ~0, which will exceed the maximum
> supported bits of identifier.
Well, the problem is that nr_ites should never be 1, as it effectively
means "don't use any bit to index the ITE". And it also means we cannot
have an ITT that's not a strict power of two.
So while this is indeed a bug, the root of the problem is elsewhere.
I'll cook a fix, thanks for the report.
Jazz is not dead. It just smells funny...
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