[PATCH 4/8] xen: Use the correctly the Xen memory terminologies
boris.ostrovsky at oracle.com
Wed Jul 29 05:12:11 AEST 2015
On 07/28/2015 11:02 AM, Julien Grall wrote:
> Based on include/xen/mm.h , 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 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.
> @@ -730,7 +730,7 @@ static void xen_do_pin(unsigned level, unsigned long pfn)
> struct mmuext_op op;
> op.cmd = level;
> - op.arg1.mfn = pfn_to_mfn(pfn);
> + op.arg1.mfn = pfn_to_gfn(pfn);
This looks slightly odd. It is correct but given that purpose of this
series is to make things more clear perhaps we can add another union
member (gfn) to mmuext_op.arg1?
(Of course, the hypervisor will continue referring to mfn which could
still be confusing)
> @@ -1323,7 +1323,7 @@ static void __xen_write_cr3(bool kernel, unsigned long cr3)
> trace_xen_mmu_write_cr3(kernel, cr3);
> if (cr3)
> - mfn = pfn_to_mfn(PFN_DOWN(cr3));
> + mfn = pfn_to_gfn(PFN_DOWN(cr3));
Here too. And further down, thoughout this patch.
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