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Fri, 24 Jul 2020 10:34:50 -0400 X-MC-Unique: WvzseDkuOl2JB5UQZyg1rA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2E5581083E8E; Fri, 24 Jul 2020 14:34:46 +0000 (UTC) Received: from [10.36.113.94] (ovpn-113-94.ams2.redhat.com [10.36.113.94]) by smtp.corp.redhat.com (Postfix) with ESMTP id 228CF10027A6; Fri, 24 Jul 2020 14:34:41 +0000 (UTC) Subject: Re: [PATCH v2 4/4] xen: add helpers to allocate unpopulated memory To: Roger Pau Monne , linux-kernel@vger.kernel.org Cc: Oleksandr Andrushchenko , David Airlie , Daniel Vetter , Boris Ostrovsky , Juergen Gross , Stefano Stabellini , Dan Carpenter , Wei Liu , Yan Yankovskyi , dri-devel@lists.freedesktop.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org, Michal Hocko , Dan Williams References: <20200724124241.48208-1-roger.pau@citrix.com> <20200724124241.48208-5-roger.pau@citrix.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200724124241.48208-5-roger.pau@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Rspamd-Queue-Id: BD8CD18A73 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: CCing Dan On 24.07.20 14:42, Roger Pau Monne wrote: > To be used in order to create foreign mappings. This is based on the > ZONE_DEVICE facility which is used by persistent memory devices in > order to create struct pages and kernel virtual mappings for the IOMEM > areas of such devices. Note that on kernels without support for > ZONE_DEVICE Xen will fallback to use ballooned pages in order to > create foreign mappings. >=20 > The newly added helpers use the same parameters as the existing > {alloc/free}_xenballooned_pages functions, which allows for in-place > replacement of the callers. Once a memory region has been added to be > used as scratch mapping space it will no longer be released, and pages > returned are kept in a linked list. This allows to have a buffer of > pages and prevents resorting to frequent additions and removals of > regions. >=20 > If enabled (because ZONE_DEVICE is supported) the usage of the new > functionality untangles Xen balloon and RAM hotplug from the usage of > unpopulated physical memory ranges to map foreign pages, which is the > correct thing to do in order to avoid mappings of foreign pages depend > on memory hotplug. >=20 > Signed-off-by: Roger Pau Monn=C3=A9 > --- > I've not added a new memory_type type and just used > MEMORY_DEVICE_DEVDAX which seems to be what we want for such memory > regions. I'm unsure whether abusing this type is fine, or if I should > instead add a specific type, maybe MEMORY_DEVICE_GENERIC? I don't > think we should be using a specific Xen type at all. > --- > Cc: Oleksandr Andrushchenko > Cc: David Airlie > Cc: Daniel Vetter > Cc: Boris Ostrovsky > Cc: Juergen Gross > Cc: Stefano Stabellini > Cc: Dan Carpenter > Cc: Roger Pau Monne > Cc: Wei Liu > Cc: Yan Yankovskyi > Cc: dri-devel@lists.freedesktop.org > Cc: xen-devel@lists.xenproject.org > Cc: linux-mm@kvack.org > Cc: David Hildenbrand > Cc: Michal Hocko > --- > drivers/gpu/drm/xen/xen_drm_front_gem.c | 8 +- > drivers/xen/Makefile | 1 + > drivers/xen/balloon.c | 4 +- > drivers/xen/grant-table.c | 4 +- > drivers/xen/privcmd.c | 4 +- > drivers/xen/unpopulated-alloc.c | 222 ++++++++++++++++++++++++ > drivers/xen/xenbus/xenbus_client.c | 6 +- > drivers/xen/xlate_mmu.c | 4 +- > include/xen/xen.h | 8 + > 9 files changed, 246 insertions(+), 15 deletions(-) > create mode 100644 drivers/xen/unpopulated-alloc.c >=20 > diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/= xen/xen_drm_front_gem.c > index f0b85e094111..9dd06eae767a 100644 > --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c > +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c > @@ -99,8 +99,8 @@ static struct xen_gem_object *gem_create(struct drm_d= evice *dev, size_t size) > * allocate ballooned pages which will be used to map > * grant references provided by the backend > */ > - ret =3D alloc_xenballooned_pages(xen_obj->num_pages, > - xen_obj->pages); > + ret =3D xen_alloc_unpopulated_pages(xen_obj->num_pages, > + xen_obj->pages); > if (ret < 0) { > DRM_ERROR("Cannot allocate %zu ballooned pages: %d\n", > xen_obj->num_pages, ret); > @@ -152,8 +152,8 @@ void xen_drm_front_gem_free_object_unlocked(struct = drm_gem_object *gem_obj) > } else { > if (xen_obj->pages) { > if (xen_obj->be_alloc) { > - free_xenballooned_pages(xen_obj->num_pages, > - xen_obj->pages); > + xen_free_unpopulated_pages(xen_obj->num_pages, > + xen_obj->pages); > gem_free_pages_array(xen_obj); > } else { > drm_gem_put_pages(&xen_obj->base, > diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile > index 0d322f3d90cd..788a5d9c8ef0 100644 > --- a/drivers/xen/Makefile > +++ b/drivers/xen/Makefile > @@ -42,3 +42,4 @@ xen-gntdev-$(CONFIG_XEN_GNTDEV_DMABUF) +=3D gntdev-dm= abuf.o > xen-gntalloc-y :=3D gntalloc.o > xen-privcmd-y :=3D privcmd.o privcmd-buf.o > obj-$(CONFIG_XEN_FRONT_PGDIR_SHBUF) +=3D xen-front-pgdir-shbuf.o > +obj-$(CONFIG_ZONE_DEVICE) +=3D unpopulated-alloc.o > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c > index b1d8b028bf80..815ef10eb2ff 100644 > --- a/drivers/xen/balloon.c > +++ b/drivers/xen/balloon.c > @@ -654,7 +654,7 @@ void free_xenballooned_pages(int nr_pages, struct p= age **pages) > } > EXPORT_SYMBOL(free_xenballooned_pages); > =20 > -#ifdef CONFIG_XEN_PV > +#if defined(CONFIG_XEN_PV) && !defined(CONFIG_ZONE_DEVICE) > static void __init balloon_add_region(unsigned long start_pfn, > unsigned long pages) > { > @@ -708,7 +708,7 @@ static int __init balloon_init(void) > register_sysctl_table(xen_root); > #endif > =20 > -#ifdef CONFIG_XEN_PV > +#if defined(CONFIG_XEN_PV) && !defined(CONFIG_ZONE_DEVICE) > { > int i; > =20 > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index 8d06bf1cc347..523dcdf39cc9 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -801,7 +801,7 @@ int gnttab_alloc_pages(int nr_pages, struct page **= pages) > { > int ret; > =20 > - ret =3D alloc_xenballooned_pages(nr_pages, pages); > + ret =3D xen_alloc_unpopulated_pages(nr_pages, pages); > if (ret < 0) > return ret; > =20 > @@ -836,7 +836,7 @@ EXPORT_SYMBOL_GPL(gnttab_pages_clear_private); > void gnttab_free_pages(int nr_pages, struct page **pages) > { > gnttab_pages_clear_private(nr_pages, pages); > - free_xenballooned_pages(nr_pages, pages); > + xen_free_unpopulated_pages(nr_pages, pages); > } > EXPORT_SYMBOL_GPL(gnttab_free_pages); > =20 > diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c > index a250d118144a..56000ab70974 100644 > --- a/drivers/xen/privcmd.c > +++ b/drivers/xen/privcmd.c > @@ -425,7 +425,7 @@ static int alloc_empty_pages(struct vm_area_struct = *vma, int numpgs) > if (pages =3D=3D NULL) > return -ENOMEM; > =20 > - rc =3D alloc_xenballooned_pages(numpgs, pages); > + rc =3D xen_alloc_unpopulated_pages(numpgs, pages); > if (rc !=3D 0) { > pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__, > numpgs, rc); > @@ -900,7 +900,7 @@ static void privcmd_close(struct vm_area_struct *vm= a) > =20 > rc =3D xen_unmap_domain_gfn_range(vma, numgfns, pages); > if (rc =3D=3D 0) > - free_xenballooned_pages(numpgs, pages); > + xen_free_unpopulated_pages(numpgs, pages); > else > pr_crit("unable to unmap MFN range: leaking %d pages. rc=3D%d\n", > numpgs, rc); > diff --git a/drivers/xen/unpopulated-alloc.c b/drivers/xen/unpopulated-= alloc.c > new file mode 100644 > index 000000000000..aaa91cefbbf9 > --- /dev/null > +++ b/drivers/xen/unpopulated-alloc.c > @@ -0,0 +1,222 @@ > +/* > + * Helpers to allocate unpopulated memory for foreign mappings > + * > + * Copyright (c) 2020, Citrix Systems R&D > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License version= 2 > + * as published by the Free Software Foundation; or, when distributed > + * separately from the Linux kernel or incorporated into other > + * software packages, subject to the following license: > + * > + * Permission is hereby granted, free of charge, to any person obtaini= ng a copy > + * of this source file (the "Software"), to deal in the Software witho= ut > + * restriction, including without limitation the rights to use, copy, = modify, > + * merge, publish, distribute, sublicense, and/or sell copies of the S= oftware, > + * and to permit persons to whom the Software is furnished to do so, s= ubject to > + * the following conditions: > + * > + * The above copyright notice and this permission notice shall be incl= uded in > + * all copies or substantial portions of the Software. > + * > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXP= RESS OR > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABI= LITY, > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT S= HALL THE > + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OT= HER > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARI= SING > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER= DEALINGS > + * IN THE SOFTWARE. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > + > +#include > +#include > + > +static DEFINE_MUTEX(lock); > +static LIST_HEAD(list); > +static unsigned int count; > + > +static int fill(unsigned int nr_pages) > +{ > + struct dev_pagemap *pgmap; > + void *vaddr; > + unsigned int i, alloc_pages =3D round_up(nr_pages, PAGES_PER_SECTION)= ; > + int nid, ret; > + > + pgmap =3D kzalloc(sizeof(*pgmap), GFP_KERNEL); > + if (!pgmap) > + return -ENOMEM; > + > + pgmap->type =3D MEMORY_DEVICE_DEVDAX; > + pgmap->res.name =3D "XEN SCRATCH"; > + pgmap->res.flags =3D IORESOURCE_MEM | IORESOURCE_BUSY; > + > + ret =3D allocate_resource(&iomem_resource, &pgmap->res, > + alloc_pages * PAGE_SIZE, 0, -1, > + PAGES_PER_SECTION * PAGE_SIZE, NULL, NULL); > + if (ret < 0) { > + pr_err("Cannot allocate new IOMEM resource\n"); > + kfree(pgmap); > + return ret; > + } > + > + nid =3D memory_add_physaddr_to_nid(pgmap->res.start); > + > +#ifdef CONFIG_XEN_HAVE_PVMMU > + /* > + * We don't support PV MMU when Linux and Xen is using > + * different page granularity. > + */ > + BUILD_BUG_ON(XEN_PAGE_SIZE !=3D PAGE_SIZE); > + > + /* > + * memremap will build page tables for the new memory so > + * the p2m must contain invalid entries so the correct > + * non-present PTEs will be written. > + * > + * If a failure occurs, the original (identity) p2m entries > + * are not restored since this region is now known not to > + * conflict with any devices. > + */ > + if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + xen_pfn_t pfn =3D PFN_DOWN(pgmap->res.start); > + > + for (i =3D 0; i < alloc_pages; i++) { > + if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) { > + pr_warn("set_phys_to_machine() failed, no memory added\n"); > + release_resource(&pgmap->res); > + kfree(pgmap); > + return -ENOMEM; > + } > + } > + } > +#endif > + > + vaddr =3D memremap_pages(pgmap, nid); > + if (IS_ERR(vaddr)) { > + pr_err("Cannot remap memory range\n"); > + release_resource(&pgmap->res); > + kfree(pgmap); > + return PTR_ERR(vaddr); > + } > + > + for (i =3D 0; i < alloc_pages; i++) { > + struct page *pg =3D virt_to_page(vaddr + PAGE_SIZE * i); > + > + BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i)); > + list_add(&pg->lru, &list); > + count++; > + } > + > + return 0; > +} > + > +/** > + * xen_alloc_unpopulated_pages - alloc unpopulated pages > + * @nr_pages: Number of pages > + * @pages: pages returned > + * @return 0 on success, error otherwise > + */ > +int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **p= ages) > +{ > + unsigned int i; > + int ret =3D 0; > + > + mutex_lock(&lock); > + if (count < nr_pages) { > + ret =3D fill(nr_pages); > + if (ret) > + goto out; > + } > + > + for (i =3D 0; i < nr_pages; i++) { > + struct page *pg =3D list_first_entry_or_null(&list, struct page, > + lru); > + > + BUG_ON(!pg); > + list_del(&pg->lru); > + count--; > + pages[i] =3D pg; > + > +#ifdef CONFIG_XEN_HAVE_PVMMU > + /* > + * We don't support PV MMU when Linux and Xen is using > + * different page granularity. > + */ > + BUILD_BUG_ON(XEN_PAGE_SIZE !=3D PAGE_SIZE); > + > + if (!xen_feature(XENFEAT_auto_translated_physmap)) { > + ret =3D xen_alloc_p2m_entry(page_to_pfn(pg)); > + if (ret < 0) { > + unsigned int j; > + > + for (j =3D 0; j <=3D i; j++) { > + list_add(&pages[j]->lru, &list); > + count++; > + } > + goto out; > + } > + } > +#endif > + } > + > +out: > + mutex_unlock(&lock); > + return ret; > +} > +EXPORT_SYMBOL(xen_alloc_unpopulated_pages); > + > +/** > + * xen_free_unpopulated_pages - return unpopulated pages > + * @nr_pages: Number of pages > + * @pages: pages to return > + */ > +void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **p= ages) > +{ > + unsigned int i; > + > + mutex_lock(&lock); > + for (i =3D 0; i < nr_pages; i++) { > + list_add(&pages[i]->lru, &list); > + count++; > + } > + mutex_unlock(&lock); > +} > +EXPORT_SYMBOL(xen_free_unpopulated_pages); > + > +#ifdef CONFIG_XEN_PV > +static int __init init(void) > +{ > + unsigned int i; > + > + if (!xen_domain()) > + return -ENODEV; > + > + /* > + * Initialize with pages from the extra memory regions (see > + * arch/x86/xen/setup.c). > + */ > + for (i =3D 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { > + unsigned int j; > + > + for (j =3D 0; j < xen_extra_mem[i].n_pfns; j++) { > + struct page *pg =3D > + pfn_to_page(xen_extra_mem[i].start_pfn + j); > + > + list_add(&pg->lru, &list); > + count++; > + } > + } > + > + return 0; > +} > +subsys_initcall(init); > +#endif > diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xe= nbus_client.c > index 786fbb7d8be0..70b6c4780fbd 100644 > --- a/drivers/xen/xenbus/xenbus_client.c > +++ b/drivers/xen/xenbus/xenbus_client.c > @@ -615,7 +615,7 @@ static int xenbus_map_ring_hvm(struct xenbus_device= *dev, > bool leaked =3D false; > unsigned int nr_pages =3D XENBUS_PAGES(nr_grefs); > =20 > - err =3D alloc_xenballooned_pages(nr_pages, node->hvm.pages); > + err =3D xen_alloc_unpopulated_pages(nr_pages, node->hvm.pages); > if (err) > goto out_err; > =20 > @@ -656,7 +656,7 @@ static int xenbus_map_ring_hvm(struct xenbus_device= *dev, > addr, nr_pages); > out_free_ballooned_pages: > if (!leaked) > - free_xenballooned_pages(nr_pages, node->hvm.pages); > + xen_free_unpopulated_pages(nr_pages, node->hvm.pages); > out_err: > return err; > } > @@ -852,7 +852,7 @@ static int xenbus_unmap_ring_hvm(struct xenbus_devi= ce *dev, void *vaddr) > info.addrs); > if (!rv) { > vunmap(vaddr); > - free_xenballooned_pages(nr_pages, node->hvm.pages); > + xen_free_unpopulated_pages(nr_pages, node->hvm.pages); > } > else > WARN(1, "Leaking %p, size %u page(s)\n", vaddr, nr_pages); > diff --git a/drivers/xen/xlate_mmu.c b/drivers/xen/xlate_mmu.c > index 7b1077f0abcb..34742c6e189e 100644 > --- a/drivers/xen/xlate_mmu.c > +++ b/drivers/xen/xlate_mmu.c > @@ -232,7 +232,7 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t = **gfns, void **virt, > kfree(pages); > return -ENOMEM; > } > - rc =3D alloc_xenballooned_pages(nr_pages, pages); > + rc =3D xen_alloc_unpopulated_pages(nr_pages, pages); > if (rc) { > pr_warn("%s Couldn't balloon alloc %ld pages rc:%d\n", __func__, > nr_pages, rc); > @@ -249,7 +249,7 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t = **gfns, void **virt, > if (!vaddr) { > pr_warn("%s Couldn't map %ld pages rc:%d\n", __func__, > nr_pages, rc); > - free_xenballooned_pages(nr_pages, pages); > + xen_free_unpopulated_pages(nr_pages, pages); > kfree(pages); > kfree(pfns); > return -ENOMEM; > diff --git a/include/xen/xen.h b/include/xen/xen.h > index 19a72f591e2b..aa33bc0d933c 100644 > --- a/include/xen/xen.h > +++ b/include/xen/xen.h > @@ -52,4 +52,12 @@ bool xen_biovec_phys_mergeable(const struct bio_vec = *vec1, > extern u64 xen_saved_max_mem_size; > #endif > =20 > +#ifdef CONFIG_ZONE_DEVICE > +int xen_alloc_unpopulated_pages(unsigned int nr_pages, struct page **p= ages); > +void xen_free_unpopulated_pages(unsigned int nr_pages, struct page **p= ages); > +#else > +#define xen_alloc_unpopulated_pages alloc_xenballooned_pages > +#define xen_free_unpopulated_pages free_xenballooned_pages > +#endif > + > #endif /* _XEN_XEN_H */ >=20 --=20 Thanks, David / dhildenb