Re: [Qemu-devel] [RFC 1/1] ide: bug #1777315: io_buffer_size and sg.size can represent partial sector sizes

[John Snow <jsnow@redhat.com>]

On 06/18/2018 02:02 PM, Amol Surati wrote:
> On Mon, Jun 18, 2018 at 12:05:15AM +0530, Amol Surati wrote:
>> This patch fixes the assumption that io_buffer_size is always a perfect
>> multiple of the sector size. The assumption is the cause of the firing
>> of 'assert(n * 512 == s->sg.size);'.
>>
>> Signed-off-by: Amol Surati <suratiamol@gmail.com>
>> ---
> 
> The repository https://github.com/asurati/1777315 contains a module for
> QEMU's 8086:7010 ATA controller, which exercises the code path
> described in [RFC 0/1] of this series.
> 
> Loading the module reproduces the bug. Tested on the latest master
> branch.
> 
> Steps:
> - Install a Linux distribution as a guest, ensuring that the boot disk
>   resides on non-IDE controllers (such as virtio)
> - Attach another disk as a master device on the primary
>   IDE controller (i.e. attach at -hda.)
> - Blacklist ata_piix, pata_acpi and ata_generic modules, and reboot.
> - Copy the source files into the guest and build the module.
> - Load the module. QEMU process should die with the message:
>   qemu-system-x86_64: hw/ide/core.c:871: ide_dma_cb:
>   Assertion `n * 512 == s->sg.size' failed.
> 
> 
> -Amol
> 

Are you the original reporter as well?

I'm looking at the patch and the reproducer now, thanks.

--js