Skip to content

Commit

Permalink
xen/privcmd: Add support for Linux 64KB page granularity
Browse files Browse the repository at this point in the history 
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 <julien.grall@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
  • Loading branch information
Julien Grall authored and David Vrabel committed Oct 23, 2015
1 parent d0089e8 commit 5995a68
Show file tree
Hide file tree
Showing 2 changed files with 89 additions and 43 deletions.
8 changes: 5 additions & 3 deletions drivers/xen/privcmd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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
Expand All @@ -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));
Expand Down Expand Up @@ -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
Expand Down
124 changes: 84 additions & 40 deletions drivers/xen/xlate_mmu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -38,31 +38,28 @@
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>

/* 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];
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;
Expand All @@ -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;
}
Expand All @@ -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;
Expand All @@ -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);

0 comments on commit 5995a68

Please sign in to comment.