Re: [PATCH v1 3/6] xen/arm: create dom0less virtio-pci DT node

[Stewart Hildebrand <stewart.hildebrand@xxxxxxx>]

On 9/24/24 19:55, Stefano Stabellini wrote:
> On Tue, 24 Sep 2024, Edgar E. Iglesias wrote:
>> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
>> index 09b65e44ae..dab24fa9e2 100644
>> --- a/xen/arch/arm/dom0less-build.c
>> +++ b/xen/arch/arm/dom0less-build.c
>> @@ -744,11 +934,24 @@ static int __init alloc_xenstore_evtchn(struct domain 
>> *d)
>>      return 0;
>>  }
>>  
>> +static u64 combine_u64(u32 v[2])
> 
> Let's make this a static inline or a macro. I can't believe we don't
> have one already.

We have dt_read_number(). You'd need to use it with dt_get_property().
In this case, it might look something like:

__be32 *val = dt_get_property(node, "virtio-pci-ranges", &len);

/* TODO: check len */

...ecam.base = dt_read_number(&val[0], 2);
...mem.base = dt_read_number(&val[2], 2);
...pf_mem.base = dt_read_number(&val[4], 2);

>> +{
>> +    u64 v64;
>> +
>> +    v64 = v[0];
>> +    v64 <<= 32;
>> +    v64 |= v[1];
>> +    return v64;
>> +}
>> +
>>  static int __init construct_domU(struct domain *d,
>>                                   const struct dt_device_node *node)
>>  {
>>      struct kernel_info kinfo = KERNEL_INFO_INIT;
>>      const char *dom0less_enhanced;
>> +    const char *virtio_pci;
>> +    /* virtio-pci ECAM, MEM, PF-MEM each carrying 2 x Address cells.  */
>> +    u32 virtio_pci_ranges[3 * 2];
>>      int rc;
>>      u64 mem;
>>      u32 p2m_mem_mb;
>> @@ -779,6 +982,41 @@ static int __init construct_domU(struct domain *d,
>>  
>>      kinfo.vpl011 = dt_property_read_bool(node, "vpl011");
>>  
>> +    rc = dt_property_read_string(node, "virtio-pci", &virtio_pci);
>> +    if ( !rc )
>> +    {
>> +        if ( !strcmp(virtio_pci, "enabled") )
>> +            kinfo.virtio_pci.mode = VIRTIO_PCI;
>> +        else if ( !strcmp(virtio_pci, "grants") )
>> +            kinfo.virtio_pci.mode = VIRTIO_PCI_GRANTS;
>> +        else
>> +        {
>> +            printk("Invalid \"virtio-pci\" property value (%s)\n", 
>> virtio_pci);
>> +            return -EINVAL;
>> +        }
>> +    }
>> +    else if ( rc == -ENODATA )
>> +    {
>> +        /* Handle missing property value */
>> +        kinfo.virtio_pci.mode = dt_property_read_bool(node, "virtio-pci");
>> +    }
>> +
>> +    if ( kinfo.virtio_pci.mode != VIRTIO_PCI_NONE )
>> +    {
>> +        rc = dt_property_read_u32_array(node, "virtio-pci-ranges",
>> +                                        virtio_pci_ranges,
>> +                                        ARRAY_SIZE(virtio_pci_ranges));
>> +        if ( rc == 0 ) {
>> +            kinfo.virtio_pci.ecam.base = combine_u64(&virtio_pci_ranges[0]);
>> +            kinfo.virtio_pci.mem.base = combine_u64(&virtio_pci_ranges[2]);
>> +            kinfo.virtio_pci.pf_mem.base = 
>> combine_u64(&virtio_pci_ranges[4]);
>> +        } else {
>> +            kinfo.virtio_pci.ecam.base = GUEST_VIRTIO_PCI_ECAM_BASE;
>> +            kinfo.virtio_pci.mem.base = GUEST_VIRTIO_PCI_MEM_BASE;
>> +            kinfo.virtio_pci.pf_mem.base = 
>> GUEST_VIRTIO_PCI_PREFETCH_MEM_BASE;
>> +        }
>> +    }
>> +
>>      rc = dt_property_read_string(node, "xen,enhanced", &dom0less_enhanced);
>>      if ( rc == -EILSEQ ||
>>           rc == -ENODATA ||