[SLOF] [PATCH v2 12/19] virtio: add 64-bit virtio helpers for 1.0

[Alexey Kardashevskiy]

On 01/22/2016 05:30 PM, Thomas Huth wrote:
> On 22.01.2016 06:25, Alexey Kardashevskiy wrote:
>> On 01/22/2016 04:18 PM, Nikunj A Dadhania wrote:
>>> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>>>
>>>> On 01/21/2016 06:58 PM, Nikunj A Dadhania wrote:
>>>>> Thomas Huth <thuth at redhat.com> writes:
>>>>>
>>>>>> On 20.01.2016 13:10, Nikunj A Dadhania wrote:
>>>>>>>     } __attribute__ ((packed));
>>>>>>>
>>>>>>> +/* virtio 1.0 Spec: 4.1.3 PCI Device Layout
>>>>>>> + *
>>>>>>> + * Fields of different sizes are present in the device
>>>>>>> configuration regions.
>>>>>>> + * All 64-bit, 32-bit and 16-bit fields are little-endian. 64-bit
>>>>>>> fields are to
>>>>>>> + * be treated as two 32-bit fields, with low 32 bit part followed
>>>>>>> by the high 32
>>>>>>> + * bit part.
>>>>>>> + */
>>>>>>> +static void virtio_write64(void *addr, uint64_t val)
>>>>>>> +{
>>>>>>> +    uint32_t hi = (val >> 32) & 0xFFFFFFFF;
>>>>>>> +    uint32_t lo = val & 0xFFFFFFFF;
>>>>>>> +
>>>>>>> +    ci_write_32(addr, cpu_to_le32(lo));
>>>>>>> +    ci_write_32(addr + 4, cpu_to_le32(hi));
>>>>>>> +}
>>>>>>> +
>>>>>>> +static uint64_t virtio_read64(void *addr)
>>>>>>> +{
>>>>>>> +    uint64_t hi, lo;
>>>>>>> +
>>>>>>> +    lo = le32_to_cpu(ci_read_32(addr));
>>>>>>> +    hi = le32_to_cpu(ci_read_32(addr + 4));
>>>>>>> +    return (hi << 32) | lo;
>>>>>>> +}
>>>>>>
>>>>>> I'd maybe name them "virtio_pci_write64" and "virtio_pci_read64" to
>>>>>> make
>>>>>> it clear that they are only to be used when reading and writing to the
>>>>>> PCI space - otherwise somebody might use them for accessing the virtio
>>>>>> rings one day, for example.
>>>>>
>>>>> Right, will rename.
>>>>
>>>>
>>>> I'd rename these to virtio_ci_write_64/virtio_ci_read_64 as they are
>>>> wrappers on top of ci_read_xx/ci_write_xx. And frankly they can be
>>>> used to
>>>> access any guest physical memory and any MMIO.
>>>
>>> They can be used, but should not be, as the register in MMIO are not
>>> split into two registers (hi,low).This is  very specific to VIRTIO PCI.
>>> IMO, the current naming is correct.
>>
>>
>> This is why I kept "virtio_" prefix. PCI is redundant here - there is no
>> other virtio, and "ci" is what it really does. Thomas?
>
> The split for 2x 32-bit only makes sense for the PCI access, so I'd also
> use "_pci_" here.


Ok, PCI config space cannot be accessed by 8 bytes. Then remove "virtio_" 
from these helpers.



-- 
Alexey