From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= Subject: Re: [PATCH RFC 1/2] gnttab: add IOMMU entries for grant mappings on auto-translated guests Date: Mon, 7 Apr 2014 13:51:58 +0200 Message-ID: <5342915E.1090900@citrix.com> References: <1396622254-13069-1-git-send-email-roger.pau@citrix.com> <1396622254-13069-2-git-send-email-roger.pau@citrix.com> <533EED620200007800005C88@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WX860-00055M-Ry for xen-devel@lists.xenproject.org; Mon, 07 Apr 2014 11:52:13 +0000 In-Reply-To: <533EED620200007800005C88@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel@lists.xenproject.org, Keir Fraser List-Id: xen-devel@lists.xenproject.org On 04/04/14 17:35, Jan Beulich wrote: >>>> On 04.04.14 at 16:37, wrote: >> --- a/xen/common/grant_table.c >> +++ b/xen/common/grant_table.c >> @@ -749,6 +749,22 @@ __gnttab_map_grant_ref( >> goto undo_out; >> } >> } >> + else if ( need_iommu(ld) ) >> + { >> + int err; >> + >> + BUG_ON(!paging_mode_translate(ld)); >> + err = iommu_map_page(ld, op->host_addr >> PAGE_SHIFT, frame, >> + op->flags & GNTMAP_readonly ? >> + IOMMUF_readable : >> + IOMMUF_readable|IOMMUF_writable); >> + if ( err ) >> + { >> + double_gt_unlock(lgt, rgt); >> + rc = GNTST_general_error; >> + goto undo_out; >> + } >> + } > > As much of this as possible should be folded with the if() branch. > And looking at the PV code, I think it makes no sense for the > conditions whether to map the page r/o or r/w to be different > between PV and non-PV. > > Plus - wouldn't it be better to have this taken care of via > create_grant_host_mapping(), by not blindly calling > iommu_unmap_page() on anything other than p2m_ram_rw in > ept_set_entry() and p2m_set_entry(), the more that this should > already be taken care of in the iommu_hap_pt_share case. Thanks for the comment, it indeed makes much more sense to fix this in ept_set_entry/p2m_set_entry, the following patch adds IOMMU support for all page types except p2m_mmio_direct (when the hap memory map is not shared with IOMMU): --- diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c index beb7288..611c8e2 100644 --- a/xen/arch/x86/mm/p2m-ept.c +++ b/xen/arch/x86/mm/p2m-ept.c @@ -475,18 +475,22 @@ out: iommu_pte_flush(d, gfn, (u64*)ept_entry, order, vtd_pte_present); else { - if ( p2mt == p2m_ram_rw ) + if ( (p2mt != p2m_invalid) && (p2mt != p2m_mmio_direct) ) { + unsigned int flags; + + flags = ( (p2mt == p2m_grant_map_ro) || (p2mt == p2m_ram_ro) ) ? + IOMMUF_readable : IOMMUF_readable | IOMMUF_writable; if ( order > 0 ) { for ( i = 0; i < (1 << order); i++ ) iommu_map_page( p2m->domain, gfn - offset + i, mfn_x(mfn) - offset + i, - IOMMUF_readable | IOMMUF_writable); + flags); } else if ( !order ) iommu_map_page( - p2m->domain, gfn, mfn_x(mfn), IOMMUF_readable | IOMMUF_writable); + p2m->domain, gfn, mfn_x(mfn), flags); } else { diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c index 766fd67..c564cb6 100644 --- a/xen/arch/x86/mm/p2m-pt.c +++ b/xen/arch/x86/mm/p2m-pt.c @@ -450,11 +450,15 @@ p2m_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn, } else { - if ( p2mt == p2m_ram_rw ) + if ( (p2mt != p2m_invalid) && (p2mt != p2m_mmio_direct) ) + { + unsigned int flags; + + flags = ( (p2mt == p2m_grant_map_ro) || (p2mt == p2m_ram_ro) ) ? + IOMMUF_readable : IOMMUF_readable | IOMMUF_writable; for ( i = 0; i < (1UL << page_order); i++ ) - iommu_map_page(p2m->domain, gfn+i, mfn_x(mfn)+i, - IOMMUF_readable|IOMMUF_writable); - else + iommu_map_page(p2m->domain, gfn+i, mfn_x(mfn)+i, flags); + } else for ( int i = 0; i < (1UL << page_order); i++ ) iommu_unmap_page(p2m->domain, gfn+i); }