Re: [PATCH 5/5] pci-assign: Use PCI-2.3-based shared legacy interrupts

[Jan Kiszka <jan.kiszka@web.de>]

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Am 14.12.2010 01:16, Alex Williamson wrote:
> On Tue, 2010-12-14 at 00:25 +0100, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> 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.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> ---
>>  hw/device-assignment.c |   38 +++++++++++++++++++++++++++++++++-----
>>  qemu-kvm.c             |    8 ++++++++
>>  qemu-kvm.h             |    3 +++
>>  3 files changed, 44 insertions(+), 5 deletions(-)
>>
>> diff --git a/hw/device-assignment.c b/hw/device-assignment.c
>> index 26d3bd7..cf75c52 100644
>> --- a/hw/device-assignment.c
>> +++ b/hw/device-assignment.c
>> @@ -423,12 +423,21 @@ static uint8_t pci_find_cap_offset(PCIDevice *d, uint8_t cap, uint8_t start)
>>      return 0;
>>  }
>>  
>> +static uint32_t calc_assigned_dev_id(uint16_t seg, uint8_t bus, uint8_t devfn)
>> +{
>> +    return (uint32_t)seg << 16 | (uint32_t)bus << 8 | (uint32_t)devfn;
>> +}
>> +
>>  static void assigned_dev_pci_write_config(PCIDevice *d, uint32_t address,
>>                                            uint32_t val, int len)
>>  {
>>      int fd;
>>      ssize_t ret;
>>      AssignedDevice *pci_dev = container_of(d, AssignedDevice, dev);
>> +    struct kvm_assigned_pci_dev assigned_dev_data;
>> +#ifdef KVM_CAP_PCI_2_3
>> +    bool intx_masked, update_intx_mask;
>> +#endif /* KVM_CAP_PCI_2_3 */
>>  
>>      DEBUG("(%x.%x): address=%04x val=0x%08x len=%d\n",
>>            ((d->devfn >> 3) & 0x1F), (d->devfn & 0x7),
>> @@ -439,6 +448,26 @@ static void assigned_dev_pci_write_config(PCIDevice *d, uint32_t address,
>>      }
>>  
>>      if (ranges_overlap(address, len, PCI_COMMAND, 2)) {
>> +#ifdef KVM_CAP_PCI_2_3
>> +        update_intx_mask = false;
>> +        if (address == PCI_COMMAND+1) {
>> +            intx_masked = val & (PCI_COMMAND_INTX_DISABLE >> 8);
>> +            update_intx_mask = true;
>> +        } else if (len >= 2) {
>> +            intx_masked = val & PCI_COMMAND_INTX_DISABLE;
>> +            update_intx_mask = true;
>> +        }
> 
> I wonder if this might be a little cleaner as something like this.
> 
>     if (ranges_overlap(address, len, PCI_COMMAND + 1, 1) {
>         update_intx_mask = true;
>         intx_masked = (len == 1 ? val << 8 : val) & PCI_COMMAND_INTX_DISABLE;
>     }

That should even obsolete update_intx_mask - will look into this, and
also the merge bits thing.

Thanks!
Jan


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