Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752718Ab3JYW7D (ORCPT ); Fri, 25 Oct 2013 18:59:03 -0400 Received: from mail-we0-f181.google.com ([74.125.82.181]:54156 "EHLO mail-we0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514Ab3JYW7B (ORCPT ); Fri, 25 Oct 2013 18:59:01 -0400 Message-ID: <526AF79A.3050002@cantab.net> Date: Fri, 25 Oct 2013 23:58:34 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130922 Icedove/17.0.9 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, Santosh.Jodh@citrix.com, JBeulich@suse.com, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, mukesh.rathor@oracle.com, xhejtman@ics.muni.cz, yuval.shaia@oracle.com Subject: Re: [Xen-devel] [PATCH v1] Set 1-1 P2M for PCI BARs and MCFG regions - if needed. References: <1382713401-4882-1-git-send-email-konrad.wilk@oracle.com> In-Reply-To: <1382713401-4882-1-git-send-email-konrad.wilk@oracle.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2079 Lines: 61 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 --- 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 #endif /* __ASSEMBLY__ */ -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/