Messages in this thread | | | Date | Wed, 10 Dec 2014 11:20:31 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v3 04/13] irqchip: GICv3: ITS command queue |
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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.
M. -- Jazz is not dead. It just smells funny...
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