Re: [PATCH v5 13/14] xen/arm: account IO handlers for emulated PCI MSI-X

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

Hi, Roger!

On 13.01.22 15:23, Roger Pau Monné wrote:
> On Thu, Nov 25, 2021 at 01:02:50PM +0200, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>>
>> At the moment, we always allocate an extra 16 slots for IO handlers
>> (see MAX_IO_HANDLER). So while adding IO trap handlers for the emulated
>> MSI-X registers we need to explicitly tell that we have additional IO
>> handlers, so those are accounted.
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> LGTM, just one comment below. This will require an Ack from the Arm
> guys.
>
>> ---
>> Cc: Julien Grall <julien@xxxxxxx>
>> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> ---
>> This actually moved here from the part 2 of the prep work for PCI
>> passthrough on Arm as it seems to be the proper place for it.
>>
>> New in v5
>> ---
>>   xen/arch/arm/vpci.c | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/vpci.c b/xen/arch/arm/vpci.c
>> index 3d134f42d07e..902f8491e030 100644
>> --- a/xen/arch/arm/vpci.c
>> +++ b/xen/arch/arm/vpci.c
>> @@ -134,6 +134,8 @@ static int vpci_get_num_handlers_cb(struct domain *d,
>>   
>>   unsigned int domain_vpci_get_num_mmio_handlers(struct domain *d)
>>   {
>> +    unsigned int count;
>> +
>>       if ( !has_vpci(d) )
>>           return 0;
>>   
>> @@ -145,7 +147,18 @@ unsigned int domain_vpci_get_num_mmio_handlers(struct 
>> domain *d)
>>       }
>>   
>>       /* For a single emulated host bridge's configuration space. */
>> -    return 1;
>> +    count = 1;
>> +
>> +#ifdef CONFIG_HAS_PCI_MSI
>> +    /*
>> +     * There's a single MSI-X MMIO handler that deals with both PBA
>> +     * and MSI-X tables per each PCI device being passed through.
>> +     * Maximum number of emulated virtual devices is VPCI_MAX_VIRT_DEV.
>> +     */
>> +    count += VPCI_MAX_VIRT_DEV;
> You could also use IS_ENABLED(CONFIG_HAS_PCI_MSI) since
> VPCI_MAX_VIRT_DEV is defined unconditionally.
Yes, will use, thank you
>
> Thanks, Roger.
Thank you,
Oleksandr