linux/drivers/xen/xlate_mmu.c
Roger Pau Monne 9e2369c06c xen: add helpers to allocate unpopulated memory
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.

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.

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.

Note the driver is currently not enabled on Arm platforms because it
would interfere with the identity mapping required on some platforms.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20200901083326.21264-4-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
2020-09-04 10:00:01 +02:00

297 lines
7.8 KiB
C

/*
* MMU operations common to all auto-translated physmap guests.
*
* Copyright (C) 2015 Citrix Systems R&D Ltd.
*
* 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 obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/xen.h>
#include <xen/xen-ops.h>
#include <xen/page.h>
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
#include <xen/balloon.h>
typedef void (*xen_gfn_fn_t)(unsigned long gfn, void *data);
/* 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;
for (i = 0; i < nr_gfn; i++) {
if ((i % XEN_PFN_PER_PAGE) == 0) {
page = pages[i / XEN_PFN_PER_PAGE];
xen_pfn = page_to_xen_pfn(page);
}
fn(pfn_to_gfn(xen_pfn++), data);
}
}
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;
int index;
struct page **pages;
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, unsigned long addr, void *data)
{
struct remap_data *info = data;
struct page *page = info->pages[info->index++];
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,
};
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++;
}
/*
* 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;
}
int xen_xlate_remap_gfn_array(struct vm_area_struct *vma,
unsigned long addr,
xen_pfn_t *gfn, int nr,
int *err_ptr, pgprot_t prot,
unsigned domid,
struct page **pages)
{
int err;
struct remap_data data;
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;
data.pages = pages;
data.index = 0;
data.err_ptr = err_ptr;
data.mapped = 0;
err = apply_to_page_range(vma->vm_mm, addr, range,
remap_pte_fn, &data);
return err < 0 ? err : data.mapped;
}
EXPORT_SYMBOL_GPL(xen_xlate_remap_gfn_array);
static void unmap_gfn(unsigned long gfn, void *data)
{
struct xen_remove_from_physmap xrp;
xrp.domid = DOMID_SELF;
xrp.gpfn = gfn;
(void)HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp);
}
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);
return 0;
}
EXPORT_SYMBOL_GPL(xen_xlate_unmap_gfn_range);
struct map_balloon_pages {
xen_pfn_t *pfns;
unsigned int idx;
};
static void setup_balloon_gfn(unsigned long gfn, void *data)
{
struct map_balloon_pages *info = data;
info->pfns[info->idx++] = gfn;
}
/**
* xen_xlate_map_ballooned_pages - map a new set of ballooned pages
* @gfns: returns the array of corresponding GFNs
* @virt: returns the virtual address of the mapped region
* @nr_grant_frames: number of GFNs
* @return 0 on success, error otherwise
*
* This allocates a set of ballooned pages and maps them into the
* kernel's address space.
*/
int __init xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt,
unsigned long nr_grant_frames)
{
struct page **pages;
xen_pfn_t *pfns;
void *vaddr;
struct map_balloon_pages data;
int rc;
unsigned long nr_pages;
BUG_ON(nr_grant_frames == 0);
nr_pages = DIV_ROUND_UP(nr_grant_frames, XEN_PFN_PER_PAGE);
pages = kcalloc(nr_pages, sizeof(pages[0]), GFP_KERNEL);
if (!pages)
return -ENOMEM;
pfns = kcalloc(nr_grant_frames, sizeof(pfns[0]), GFP_KERNEL);
if (!pfns) {
kfree(pages);
return -ENOMEM;
}
rc = 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);
kfree(pages);
kfree(pfns);
return rc;
}
data.pfns = pfns;
data.idx = 0;
xen_for_each_gfn(pages, nr_grant_frames, setup_balloon_gfn, &data);
vaddr = vmap(pages, nr_pages, 0, PAGE_KERNEL);
if (!vaddr) {
pr_warn("%s Couldn't map %ld pages rc:%d\n", __func__,
nr_pages, rc);
xen_free_unpopulated_pages(nr_pages, pages);
kfree(pages);
kfree(pfns);
return -ENOMEM;
}
kfree(pages);
*gfns = pfns;
*virt = vaddr;
return 0;
}
EXPORT_SYMBOL_GPL(xen_xlate_map_ballooned_pages);
struct remap_pfn {
struct mm_struct *mm;
struct page **pages;
pgprot_t prot;
unsigned long i;
};
static int remap_pfn_fn(pte_t *ptep, unsigned long addr, void *data)
{
struct remap_pfn *r = data;
struct page *page = r->pages[r->i];
pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
set_pte_at(r->mm, addr, ptep, pte);
r->i++;
return 0;
}
/* Used by the privcmd module, but has to be built-in on ARM */
int xen_remap_vma_range(struct vm_area_struct *vma, unsigned long addr, unsigned long len)
{
struct remap_pfn r = {
.mm = vma->vm_mm,
.pages = vma->vm_private_data,
.prot = vma->vm_page_prot,
};
return apply_to_page_range(vma->vm_mm, addr, len, remap_pfn_fn, &r);
}
EXPORT_SYMBOL_GPL(xen_remap_vma_range);