Re: [PATCH v4 3/4] pci-assign: Use PCI-2.3-based shared legacy interrupts

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-03-08 18:00, Alex Williamson wrote:
> On Thu, 2012-03-08 at 11:10 +0100, Jan Kiszka wrote:
>> Enable the new KVM feature that allows legacy interrupt sharing for
>> PCI-2.3-compliant devices. This requires to synchronize any guest
>> change of the INTx mask bit to the kernel.
>>
>> The feature is controlled by the property 'share_intx' and is off by
>> default for now.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>  hw/device-assignment.c |   25 +++++++++++++++++++++++++
>>  hw/device-assignment.h |   10 ++++++----
>>  qemu-kvm.c             |    9 +++++++++
>>  qemu-kvm.h             |    2 ++
>>  4 files changed, 42 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index a5f1abb..b7cabd4 100644
>> --- a/hw/device-assignment.c
>> +++ b/hw/device-assignment.c
>> @@ -782,6 +782,13 @@ static int assign_device(AssignedDevice *dev)
>>                  "cause host memory corruption if the device issues DMA write "
>>                  "requests!\n");
>>      }
>> +    if (dev->features & ASSIGNED_DEVICE_SHARE_INTX_MASK) {
>> +        assigned_dev_data.flags |= KVM_DEV_ASSIGN_PCI_2_3;
>> +
>> +        /* hide host-side INTx masking from the guest */
>> +        dev->emulate_config_read[PCI_COMMAND + 1] |=
>> +            PCI_COMMAND_INTX_DISABLE >> 8;
>> +    }
> 
> I think this also needs a kvm_has_intx_set_mask() check or else we're
> emulating pci2.3 intx disable support without actually backing it.

Hmm... true.

Jan

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