Re: [PATCH v2] firmware: qemu_fw_cfg.c: hold ACPI global lock during device access

[Paolo Bonzini]

On 16/03/2016 17:57, Michael S. Tsirkin wrote:
> On Tue, Mar 08, 2016 at 01:30:50PM -0500, Gabriel Somlo wrote:
>> Allowing for the future possibility of implementing AML-based
>> (i.e., firmware-triggered) access to the QEMU fw_cfg device,
>> acquire the global ACPI lock when accessing the device on behalf
>> of the guest-side sysfs driver, to prevent any potential race
>> conditions.
>>
>> Suggested-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>> Signed-off-by: Gabriel Somlo <somlo@xxxxxxx>
> 
> So this patch makes sense of course.
> 
> 
> Given the recent discussion on QEMU mailing list,
> I think there is an additional patch that we need:
> filter the files exposed to userspace by "opt/" prefix.
> 
> This will ensure that we can change all other fw cfg files
> at will without breaking guest scripts.

That makes no sense, all other fw_cfg files are firmware ABI so we
cannot change them anyway.

Paolo