Alexander Bulekov <alxndr@bu.edu> 于2020年9月9日周三 下午10:28写道：
On 200909 1258, Li Qiang wrote:
Gerd Hoffmann <kraxel@redhat.com> 于2020年9月9日周三 下午12:49写道：
On Wed, Sep 09, 2020 at 10:15:47AM +0800, Jason Wang wrote:
On 2020/9/9 上午12:41, Li Qiang wrote:
Currently the MR is not explicitly connecting with its device instead of
a opaque. In most situation this opaque is the deivce but it is not an
enforcement. This patch adds a DeviceState member of to MemoryRegion
we will use it in later patch.
I don't have a deep investigation. But I wonder whether we could make sure
of owner instead of adding a new field here.
Should be possible. There is object_dynamic_cast() which can be used to
figure whenever a given owner object is a device.
I found most caller of 'memory_region_init_io' will set the owner to
the device object.
But some of them will just set it to NULL. Do will have a clear rule
that the device's MR
'owner' should be the device object? If yes, we can use this field.
Those seem to be devices that havent't been QOM-imfied yet? Maybe those
devices are unlikely to be affected by these issues, though...
No it seems not related QOM-ified.
For i386, it seems like parallel, port80, portF0, pckbd, and xen_pvdevice .. ?
I'm guessing none of these do DMA.
In fact xen_pvdevice is MMIO but the handlers does nothing.
There are some other example than i386 such as the riscv in
hw/riscv/sifive_uart.c
If we have a rule to force the 'MR's owner to the device then we can
fix these NULL owner MR.
Thanks,
Li Qiang