[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1] Set 1-1 P2M for PCI BARs and MCFG regions - if needed.
On 25/10/13 16:03, Konrad Rzeszutek Wilk wrote: 2). Assume that INVALID_P2M_ENTRY is considered 1-1. That would require auditing of the code and also making sure that any xen_privcmd_mmap calls use the m2p_add_override. I'm not sure I understand the concern about the privcmd driver's foreign mapping ioctls (MMAPBATCH_V2 and friends) as these all deal with MFNs directly and don't use the p2m. However there are some valid cases in which we need to check for INVALID_P2M_ENTRY - balloon driver - that might be relaxed. Yes. And this behaviour will be retained. I think we only need to do the INVALID_P2M_ENTRY => 1:1 when constructing PTEs so all other callers will see INVALID_P2M_ENTRY as before. However again the P2M code and the ABI it places are not for the faint of the heart. I have no fear.If the above suggestion does work out it will reduce the amount of p2m code /and/ remove a Xen-specific PTE bit. So I think it is worth pursuing. In the meantime, the following minimal patch is a likely workaround. David 8<------------------------------- x86/mm: set _PAGE_IOMAP in io_remap_pfn_range(). Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx> --- arch/x86/include/asm/pgtable.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 3d19994..d59b22a 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -868,6 +868,9 @@ static inline pte_t pte_swp_clear_soft_dirty(pte_t pte) return pte_clear_flags(pte, _PAGE_SWP_SOFT_DIRTY); } +#define io_remap_pfn_range(vma, addr, pfn, size, prot) \ + remap_pfn_range(vma, addr, pfn, size, (prot) | _PAGE_IOMAP) + #include <asm-generic/pgtable.h> #endif /* __ASSEMBLY__ */ -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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