Re: [PATCH] hw/ide/ahci: Check for PCI device once in ahci_init()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 3/12/24 07:46, Bernhard Beschow wrote:
> Am 21. November 2024 10:01:52 UTC schrieb "Philippe Mathieu-Daudé" <philmd@linaro.org>:
>> object_dynamic_cast() is expensive; IRQ helpers are certainly
>> a bad place to call it. Since the device type won't change at
>> runtime, resolve it once when the AHCI context is initialized
>> in ahci_init().
>>
>> Reported-by: Peter Xu <peterx@redhat.com>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>> ---
>> include/hw/ide/ahci.h |  2 +-
>> hw/ide/ahci.c         | 17 +++++------------
>> 2 files changed, 6 insertions(+), 13 deletions(-)


>> @@ -196,13 +192,9 @@ static void ahci_irq_raise(AHCIState *s)
>>
>> static void ahci_irq_lower(AHCIState *s)
>> {
>> -    DeviceState *dev_state = s->container;
>> -    PCIDevice *pci_dev = (PCIDevice *) object_dynamic_cast(OBJECT(dev_state),
>> -                                                           TYPE_PCI_DEVICE);
>> -
>>      trace_ahci_irq_lower(s);
>>
>> -    if (!pci_dev || !msi_enabled(pci_dev)) {
>> +    if (!s->pci_dev || !msi_enabled(s->pci_dev)) {
>>          qemu_irq_lower(s->irq);
>>      }
>> }
> 
> By always triggering the "irq" property, it might be possible to push out the above two methods to the caller, i.e. the parent PCI device. This would make this device model independent from PCI, essentially turning it into an "IP block". At the same time this eliminates the need for the dynamic casts and AFAICS would also fix the missing PCI dependency in the Kconfig file. I could send a patch.

Oh. Please go ahead, that is appreciated!

> 
> Best regards,
> Bernhard