Re: [PATCH v3 2/3] pci-assign: Use PCI-2.3-based shared legacy interrupts

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

On 2012-03-07 19:32, Alex Williamson wrote:
> On Wed, 2012-03-07 at 19:18 +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>
>> ---
>>
>> Changes in v3:
>>  - fixed nit :)
>>
>>  hw/device-assignment.c |   24 ++++++++++++++++++++++++
>>  hw/device-assignment.h |   10 ++++++----
>>  qemu-kvm.c             |    9 +++++++++
>>  qemu-kvm.h             |    2 ++
>>  4 files changed, 41 insertions(+), 4 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index a5f1abb..e2a8479 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;
>> +    }
>>  
>>      r = kvm_assign_pci_device(kvm_state, &assigned_dev_data);
>>      if (r < 0) {
>> @@ -1121,10 +1128,25 @@ static void assigned_dev_pci_write_config(PCIDevice *pci_dev, uint32_t address,
>>                                            uint32_t val, int len)
>>  {
>>      AssignedDevice *assigned_dev = DO_UPCAST(AssignedDevice, dev, pci_dev);
>> +    uint16_t old_cmd = pci_get_word(pci_dev->config + PCI_COMMAND);
>>      uint32_t emulate_mask, full_emulation_mask;
>> +    int ret;
>>  
>>      pci_default_write_config(pci_dev, address, val, len);
>>  
>> +    if (range_covers_byte(address, len, PCI_COMMAND + 1)) {
> 
> Hmm, now that I've acked this... shouldn't we have a feature check here
> to avoid the ioctl when share_intx=false or when the host kernel doesn't
> support this?  Thanks,

Hmm, I thought I handled this, somehow. But it's not there. v4 follows...

Thanks,
Jan

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