Re: [Qemu-devel] [PATCH v3 23/23] pci: honor PCI_COMMAND_MASTER

[liu ping fan]

On Thu, Oct 11, 2012 at 4:34 PM, Avi Kivity <address@hidden> wrote:
> On 10/11/2012 05:38 AM, liu ping fan wrote:
>> On Wed, Oct 10, 2012 at 12:32 AM, Avi Kivity <address@hidden> wrote:
>>> Currently we ignore PCI_COMMAND_MASTER completely: DMA succeeds even when
>>> the bit is clear.
>>>
>>> Honor PCI_COMMAND_MASTER by inserting a memory region into the device's
>>> bus master address space, and tying its enable status to PCI_COMMAND_MASTER.
>>>
>>> Tested using
>>>
>>>   setpci -s 03 COMMAND=3
>>>
>>> while a ping was running on a NIC in slot 3.  The kernel (Linux) detected
>>> the stall and recovered after the command
>>>
>>>   setpci -s 03 COMMAND=7
>>>
>>> was issued.
>>>
>>> Signed-off-by: Avi Kivity <address@hidden>
>>> ---
>>>  hw/pci.c | 13 +++++++++++--
>>>  hw/pci.h |  1 +
>>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/hw/pci.c b/hw/pci.c
>>> index 8e8e030..7adf61b 100644
>>> --- a/hw/pci.c
>>> +++ b/hw/pci.c
>>> @@ -782,7 +782,11 @@ static PCIDevice *do_pci_register_device(PCIDevice 
>>> *pci_dev, PCIBus *bus,
>>>          /* FIXME: Make dma_context_fn use MemoryRegions instead, so this 
>>> path is
>>>           * taken unconditionally */
>>>          /* FIXME: inherit memory region from bus creator */
>>> -        address_space_init(&pci_dev->bus_master_as, get_system_memory());
>>> +        memory_region_init_alias(&pci_dev->bus_master_enable_region, "bus 
>>> master",
>>> +                                 get_system_memory(), 0,
>>> +                                 memory_region_size(get_system_memory()));
>>
>> Could we achieve that  hiding special mr from some address space?  I
>> think one approach is to limit the iommu's lookup table, but that is
>> the guest's willing.  The other one is use dummy-mr to overlap some
>> piece of region of system_memory.
>> This method will require changing the render sequence of alias mr.
>>
>> diff --git a/memory.c b/memory.c
>> index 2f68d67..cf67c66 100644
>> --- a/memory.c
>> +++ b/memory.c
>> @@ -499,6 +499,11 @@ static void render_memory_region(FlatView *view,
>>
>>      clip = addrrange_intersection(tmp, clip);
>>
>> +    /* Render subregions in priority order. */
>> +    QTAILQ_FOREACH(subregion, &mr->subregions, subregions_link) {
>> +        render_memory_region(view, subregion, base, clip, readonly);
>> +    }
>> +
>>      if (mr->alias) {
>>          int128_subfrom(&base, int128_make64(mr->alias->addr));
>>          int128_subfrom(&base, int128_make64(mr->alias_offset));
>> @@ -506,11 +511,6 @@ static void render_memory_region(FlatView *view,
>>          return;
>>      }
>>
>> -    /* Render subregions in priority order. */
>> -    QTAILQ_FOREACH(subregion, &mr->subregions, subregions_link) {
>> -        render_memory_region(view, subregion, base, clip, readonly);
>> -    }
>> -
>>
>
> I don't really follow.  We don't have any memory region that is both a
> container and an alias, so this change has no effect.  Can you describe
> what you intend?
>
Suppose iommuA takes over only a subsection of system_memory, and
forbidden to touch other space. How can we achieve this model after
adopting this series?

>
> --
> error compiling committee.c: too many arguments to function