Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751642AbbHJME5 (ORCPT ); Mon, 10 Aug 2015 08:04:57 -0400 Received: from smtp.citrix.com ([66.165.176.89]:35186 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750966AbbHJMEz (ORCPT ); Mon, 10 Aug 2015 08:04:55 -0400 X-IronPort-AV: E=Sophos;i="5.15,645,1432598400"; d="scan'208";a="289616892" Date: Mon, 10 Aug 2015 13:03:13 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Julien Grall CC: , , , , , Konrad Rzeszutek Wilk , Boris Ostrovsky , "David Vrabel" Subject: Re: [PATCH v3 19/20] xen/privcmd: Add support for Linux 64KB page granularity In-Reply-To: <1438966019-19322-20-git-send-email-julien.grall@citrix.com> Message-ID: References: <1438966019-19322-1-git-send-email-julien.grall@citrix.com> <1438966019-19322-20-git-send-email-julien.grall@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9311 Lines: 286 On Fri, 7 Aug 2015, Julien Grall wrote: > The hypercall interface (as well as the toolstack) is always using 4KB > page granularity. When the toolstack is asking for mapping a series of > guest PFN in a batch, it expects to have the page map contiguously in > its virtual memory. > > When Linux is using 64KB page granularity, the privcmd driver will have > to map multiple Xen PFN in a single Linux page. > > Note that this solution works on page granularity which is a multiple of > 4KB. > > Signed-off-by: Julien Grall > > --- > Cc: Konrad Rzeszutek Wilk > Cc: Boris Ostrovsky > Cc: David Vrabel > > I kept the hypercall arguments in remap_data to avoid allocating them on > the stack every time that remap_pte_fn is called. > I will keep like that unless someone is strongly disagree. > > Changes in v3: > - The function to split a Linux page in mutiple Xen page has > been moved internally. It was the only use (not used anymore in > the balloon) and it's not quite clear what should be the common > interface. Differ the question until someone need to use it. > - s/nr_pfn/numgfns/ to make clear that we are dealing with GFN > - Use DIV_ROUND_UP rather round_up and fix the usage in > xen_xlate_unmap_gfn_range > > Changes in v2: > - Use xen_apply_to_page > --- > drivers/xen/privcmd.c | 8 ++-- > drivers/xen/xlate_mmu.c | 124 ++++++++++++++++++++++++++++++++---------------- > 2 files changed, 89 insertions(+), 43 deletions(-) > > diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c > index c6deb87..c8798ee 100644 > --- a/drivers/xen/privcmd.c > +++ b/drivers/xen/privcmd.c > @@ -446,7 +446,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) > return -EINVAL; > } > > - nr_pages = m.num; > + nr_pages = DIV_ROUND_UP(m.num, XEN_PFN_PER_PAGE); > if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT))) > return -EINVAL; > > @@ -494,7 +494,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) > goto out_unlock; > } > if (xen_feature(XENFEAT_auto_translated_physmap)) { > - ret = alloc_empty_pages(vma, m.num); > + ret = alloc_empty_pages(vma, nr_pages); > if (ret < 0) > goto out_unlock; > } else > @@ -518,6 +518,7 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) > state.global_error = 0; > state.version = version; > > + BUILD_BUG_ON(((PAGE_SIZE / sizeof(xen_pfn_t)) % XEN_PFN_PER_PAGE) != 0); > /* mmap_batch_fn guarantees ret == 0 */ > BUG_ON(traverse_pages_block(m.num, sizeof(xen_pfn_t), > &pagelist, mmap_batch_fn, &state)); > @@ -582,12 +583,13 @@ static void privcmd_close(struct vm_area_struct *vma) > { > struct page **pages = vma->vm_private_data; > int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; > + int numgfns = (vma->vm_end - vma->vm_start) >> XEN_PAGE_SHIFT; > int rc; > > if (!xen_feature(XENFEAT_auto_translated_physmap) || !numpgs || !pages) > return; > > - rc = xen_unmap_domain_gfn_range(vma, numpgs, pages); > + rc = xen_unmap_domain_gfn_range(vma, numgfns, pages); > if (rc == 0) > free_xenballooned_pages(numpgs, pages); > else > diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c > index cff2387..a1d3904 100644 > --- a/drivers/xen/xlate_mmu.c > +++ b/drivers/xen/xlate_mmu.c > @@ -38,31 +38,28 @@ > #include > #include > > -/* map fgfn of domid to lpfn in the current domain */ > -static int map_foreign_page(unsigned long lpfn, unsigned long fgfn, > - unsigned int domid) > -{ > - int rc; > - struct xen_add_to_physmap_range xatp = { > - .domid = DOMID_SELF, > - .foreign_domid = domid, > - .size = 1, > - .space = XENMAPSPACE_gmfn_foreign, > - }; > - xen_ulong_t idx = fgfn; > - xen_pfn_t gpfn = lpfn; > - int err = 0; > +typedef void (*xen_gfn_fn_t)(unsigned long gfn, void *data); > > - set_xen_guest_handle(xatp.idxs, &idx); > - set_xen_guest_handle(xatp.gpfns, &gpfn); > - set_xen_guest_handle(xatp.errs, &err); > +/* Break down the pages in 4KB chunk and call fn for each gfn */ > +static void xen_for_each_gfn(struct page **pages, unsigned nr_gfn, > + xen_gfn_fn_t fn, void *data) > +{ > + unsigned long xen_pfn = 0; > + struct page *page; > + int i; > > - rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp); > - return rc < 0 ? rc : err; > + for (i = 0; i < nr_gfn; i++) { > + if ((i % XEN_PFN_PER_PAGE) == 0) { > + page = pages[i / XEN_PFN_PER_PAGE]; If this function is going to be called very frequently you might want to consider using a shift instead. page = pages[i >> 4]; With an appropriate macro of course. > + xen_pfn = xen_page_to_pfn(page); > + } > + fn(pfn_to_gfn(xen_pfn++), data); What is the purpose of incrementing xen_pfn here? > + } > } > > struct remap_data { > xen_pfn_t *fgfn; /* foreign domain's gfn */ > + int nr_fgfn; /* Number of foreign gfn left to map */ > pgprot_t prot; > domid_t domid; > struct vm_area_struct *vma; > @@ -71,24 +68,71 @@ struct remap_data { > struct xen_remap_gfn_info *info; > int *err_ptr; > int mapped; > + > + /* Hypercall parameters */ > + int h_errs[XEN_PFN_PER_PAGE]; > + xen_ulong_t h_idxs[XEN_PFN_PER_PAGE]; > + xen_pfn_t h_gpfns[XEN_PFN_PER_PAGE]; > + > + int h_iter; /* Iterator */ > }; > > +static void setup_hparams(unsigned long gfn, void *data) > +{ > + struct remap_data *info = data; > + > + info->h_idxs[info->h_iter] = *info->fgfn; > + info->h_gpfns[info->h_iter] = gfn; > + info->h_errs[info->h_iter] = 0; > + > + info->h_iter++; > + info->fgfn++; > +} > + > static int remap_pte_fn(pte_t *ptep, pgtable_t token, unsigned long addr, > void *data) > { > struct remap_data *info = data; > struct page *page = info->pages[info->index++]; > - unsigned long pfn = page_to_pfn(page); > - pte_t pte = pte_mkspecial(pfn_pte(pfn, info->prot)); > - int rc; > + pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), info->prot)); > + int rc, nr_gfn; > + uint32_t i; > + struct xen_add_to_physmap_range xatp = { > + .domid = DOMID_SELF, > + .foreign_domid = info->domid, > + .space = XENMAPSPACE_gmfn_foreign, > + }; > > - rc = map_foreign_page(pfn, *info->fgfn, info->domid); > - *info->err_ptr++ = rc; > - if (!rc) { > - set_pte_at(info->vma->vm_mm, addr, ptep, pte); > - info->mapped++; > + nr_gfn = min_t(typeof(info->nr_fgfn), XEN_PFN_PER_PAGE, info->nr_fgfn); > + info->nr_fgfn -= nr_gfn; > + > + info->h_iter = 0; > + xen_for_each_gfn(&page, nr_gfn, setup_hparams, info); > + BUG_ON(info->h_iter != nr_gfn); > + > + set_xen_guest_handle(xatp.idxs, info->h_idxs); > + set_xen_guest_handle(xatp.gpfns, info->h_gpfns); > + set_xen_guest_handle(xatp.errs, info->h_errs); > + xatp.size = nr_gfn; > + > + rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp); > + > + /* info->err_ptr expect to have one error status per Xen PFN */ > + for (i = 0; i < nr_gfn; i++) { > + int err = (rc < 0) ? rc : info->h_errs[i]; > + > + *(info->err_ptr++) = err; > + if (!err) > + info->mapped++; > } > - info->fgfn++; > + > + /* > + * Note: The hypercall will return 0 in most of the case if even if > + * all the fgmfn are not mapped. We still have to update the pte > + * as the userspace may decide to continue. > + */ > + if (!rc) > + set_pte_at(info->vma->vm_mm, addr, ptep, pte); > > return 0; > } > @@ -102,13 +146,14 @@ int xen_xlate_remap_gfn_array(struct vm_area_struct *vma, > { > int err; > struct remap_data data; > - unsigned long range = nr << PAGE_SHIFT; > + unsigned long range = DIV_ROUND_UP(nr, XEN_PFN_PER_PAGE) << PAGE_SHIFT; > > /* Kept here for the purpose of making sure code doesn't break > x86 PVOPS */ > BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO))); > > data.fgfn = gfn; > + data.nr_fgfn = nr; > data.prot = prot; > data.domid = domid; > data.vma = vma; > @@ -123,21 +168,20 @@ int xen_xlate_remap_gfn_array(struct vm_area_struct *vma, > } > EXPORT_SYMBOL_GPL(xen_xlate_remap_gfn_array); > > -int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma, > - int nr, struct page **pages) > +static void unmap_gfn(unsigned long gfn, void *data) > { > - int i; > + struct xen_remove_from_physmap xrp; > > - for (i = 0; i < nr; i++) { > - struct xen_remove_from_physmap xrp; > - unsigned long pfn; > + xrp.domid = DOMID_SELF; > + xrp.gpfn = gfn; > + (void)HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp); > +} > > - pfn = page_to_pfn(pages[i]); > +int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma, > + int nr, struct page **pages) > +{ > + xen_for_each_gfn(pages, nr, unmap_gfn, NULL); > > - xrp.domid = DOMID_SELF; > - xrp.gpfn = pfn; > - (void)HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp); > - } > return 0; > } > EXPORT_SYMBOL_GPL(xen_xlate_unmap_gfn_range); > -- > 2.1.4 > -- 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/