On 28/07/15 18:16, David Vrabel wrote: > On 28/07/15 16:02, Julien Grall wrote: >> Based on include/xen/mm.h [1], Linux is mistakenly using MFN when GFN >> is meant, I suspect this is because the first support for Xen was for >> PV. This brough some misimplementation of helpers on ARM and make the >> developper confused the expected behavior. > > For the benefit of other subsystem maintainers, this is a purely > mechanical change in Xen-specific terminology. It doesn't need reviews > or acks from non-Xen people (IMO). > >> For instance, with pfn_to_mfn, we expect to get an MFN based on the name. >> Although, if we look at the implementation on x86, it's returning a GFN. >> >> For clarity and avoid new confusion, replace any reference of mfn into >> gnf in any helpers used by PV drivers. >> >> Take also the opportunity to simplify simple construction such >> as pfn_to_mfn(page_to_pfn(page)) into page_to_gfn. More complex clean up >> will come in follow-up patches. >> >> I think it may be possible to do further clean up in the x86 code to >> ensure that helpers returning machine address (such as virt_address) is >> not used by no auto-translated guests. I will let x86 xen expert doing >> it. > > Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx> > > It looks a bit odd to use GFN in some of the PV code where the > hypervisor API uses MFN but overall I think using the correct > terminology where possible is best. But I'd like to have Boris's or > Konrad's opinion on this. I was thinking to introduce mfn_to_pfn & co which would be used only for PV-guest (a BUG_ON would be here to ensure it) and hypercall related. I didn't do it as I haven't much knowledge on x86 Xen and was able to decide where I have to use pfn_to_mfn. Regards, -- Julien Grall -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
