On 2025/4/10 20:34, Jan Beulich wrote: > On 09.04.2025 08:45, Jiqian Chen wrote: >> --- a/xen/drivers/pci/pci.c >> +++ b/xen/drivers/pci/pci.c >> @@ -40,7 +40,7 @@ unsigned int pci_find_cap_offset(pci_sbdf_t sbdf, unsigned >> int cap) >> } >> >> unsigned int pci_find_next_cap_ttl(pci_sbdf_t sbdf, unsigned int pos, >> - const unsigned int caps[], unsigned int >> n, >> + const unsigned int *caps, unsigned int n, > > I don't follow the need for this change. This changed is for my next patch "vpci/header: Emulate legacy capability list for host". Currently, vpci only emulates capability list for domU, not for dom0. For domU, vpci exposes a fixed capability array which calls "supported_caps". My changes want to emulate capability list for dom0. I think vpci should expose all devices capabilities to dom0. When I emulate it, I need to iterate over all capabilities without another fixed array, so I need this function to return the position of next capability directly when passing a zero length array to this function.
> >> @@ -55,6 +55,10 @@ unsigned int pci_find_next_cap_ttl(pci_sbdf_t sbdf, >> unsigned int pos, >> >> if ( id == 0xff ) >> break; >> + >> + if ( !caps || n == 0 ) >> + return pos; > > Checking n to be zero ought to suffice here? In that case it doesn't matter > what caps is. Plus if n is non-zero, it clearly is an error if caps was NULL. Two checking is to prevent null pointer errors. But as you said, if checking n to be zero is enough, then I don't need to change the definition of this function. I will change in next version. > > Jan -- Best regards, Jiqian Chen.
