Re: [Qemu-devel] [PATCH master/stable-1.0] pci: fix corrupted pci conf index register by unaligned write

[Stefan Weil <sw@weilnetz.de>]

Am 04.01.2012 15:47, schrieb Michael S. Tsirkin:
> On Wed, Jan 04, 2012 at 04:28:42PM +0200, Avi Kivity wrote:
>> Commit d0ed8076cbdc261 converted the PCI config access to the memory
>> API, but also inadvertantly changed it to accept unaligned writes,
>> and corrupt the index register in the process. This causes a regression
>> booting NetBSD.
>>
>> Fix by ignoring unaligned or non-dword writes.
>>
>> https://bugs.launchpad.net/qemu/+bug/897771
>>
>> Reported-by: Andreas Gustafsson <gson@gson.org>
>> Signed-off-by: Avi Kivity <avi@redhat.com>
>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>
>
>> ---
>>
>> hw/pci_host.c | 3 +++
>> 1 files changed, 3 insertions(+), 0 deletions(-)
>>
>> diff --git a/hw/pci_host.c b/hw/pci_host.c
>> index 44c6c20..8041778 100644
>> --- a/hw/pci_host.c
>> +++ b/hw/pci_host.c
>> @@ -101,6 +101,9 @@ static void pci_host_config_write(void *opaque, 
>> target_phys_addr_t addr,
>>
>> PCI_DPRINTF("%s addr " TARGET_FMT_plx " len %d val %"PRIx64"\n",
>> __func__, addr, len, val);
>> + if (addr != 0 || len != 4) {
>> + return;
>> + }
>> s->config_reg = val;
>> }
>>
>> -- 
>> 1.7.7.1

Non dword writes are quite common. I get them with Linux kernels, too.
Do you really want to ignore them?

And the check for unaligned writes is, well, unusual :-)

Regards,
Stefan