[PATCH v2 19/20] xen/privcmd: Add support for Linux 64KB page granularity
Julien Grall
julien.grall at citrix.com
Thu Jul 9 13:42:31 PDT 2015
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 at citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Cc: David Vrabel <david.vrabel at citrix.com>
---
Changes in v2:
- Use xen_apply_to_page
---
drivers/xen/privcmd.c | 8 +--
drivers/xen/xlate_mmu.c | 127 +++++++++++++++++++++++++++++++++---------------
2 files changed, 92 insertions(+), 43 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 5a29616..e8714b4 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_ULL(m.num, PAGE_SIZE / XEN_PAGE_SIZE);
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 nr_pfn = (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_mfn_range(vma, numpgs, pages);
+ rc = xen_unmap_domain_mfn_range(vma, nr_pfn, 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 58a5389..1fac17c 100644
--- a/drivers/xen/xlate_mmu.c
+++ b/drivers/xen/xlate_mmu.c
@@ -38,31 +38,9 @@
#include <xen/interface/xen.h>
#include <xen/interface/memory.h>
-/* map fgmfn of domid to lpfn in the current domain */
-static int map_foreign_page(unsigned long lpfn, unsigned long fgmfn,
- 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 = fgmfn;
- xen_pfn_t gpfn = lpfn;
- int err = 0;
-
- set_xen_guest_handle(xatp.idxs, &idx);
- set_xen_guest_handle(xatp.gpfns, &gpfn);
- set_xen_guest_handle(xatp.errs, &err);
-
- rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp);
- return rc < 0 ? rc : err;
-}
-
struct remap_data {
xen_pfn_t *fgmfn; /* foreign domain's gmfn */
+ xen_pfn_t *efgmfn; /* pointer to the end of the fgmfn array */
pgprot_t prot;
domid_t domid;
struct vm_area_struct *vma;
@@ -71,24 +49,75 @@ struct remap_data {
struct xen_remap_mfn_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 int setup_hparams(struct page *page, unsigned long pfn, void *data)
+{
+ struct remap_data *info = data;
+
+ /* We may not have enough domain's gmfn to fill a Linux Page */
+ if (info->fgmfn == info->efgmfn)
+ return 0;
+
+ info->h_idxs[info->h_iter] = *info->fgmfn;
+ info->h_gpfns[info->h_iter] = pfn;
+ info->h_errs[info->h_iter] = 0;
+ info->h_iter++;
+
+ info->fgmfn++;
+
+ return 0;
+}
+
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));
+ pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), info->prot));
int rc;
+ 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->fgmfn, info->domid);
- *info->err_ptr++ = rc;
- if (!rc) {
- set_pte_at(info->vma->vm_mm, addr, ptep, pte);
- info->mapped++;
+ info->h_iter = 0;
+
+ /* setup_hparams guarantees ret == 0 */
+ BUG_ON(xen_apply_to_page(page, setup_hparams, info));
+
+ 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 = info->h_iter;
+
+ 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 < info->h_iter; i++) {
+ int err = (rc < 0) ? rc : info->h_errs[i];
+
+ *(info->err_ptr++) = err;
+ if (!err)
+ info->mapped++;
}
- info->fgmfn++;
+
+ /*
+ * 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 +131,14 @@ 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 = round_up(nr, XEN_PFN_PER_PAGE) << XEN_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.fgmfn = mfn;
+ data.efgmfn = mfn + nr;
data.prot = prot;
data.domid = domid;
data.vma = vma;
@@ -123,21 +153,38 @@ int xen_xlate_remap_gfn_array(struct vm_area_struct *vma,
}
EXPORT_SYMBOL_GPL(xen_xlate_remap_gfn_array);
+static int unmap_gfn(struct page *page, unsigned long pfn, void *data)
+{
+ int *nr = data;
+ struct xen_remove_from_physmap xrp;
+
+ /* The Linux Page may not have been fully mapped to Xen */
+ if (!*nr)
+ return 0;
+
+ xrp.domid = DOMID_SELF;
+ xrp.gpfn = pfn;
+ (void)HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrp);
+
+ (*nr)--;
+
+ return 0;
+}
+
int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma,
int nr, struct page **pages)
{
int i;
+ int nr_page = round_up(nr, XEN_PFN_PER_PAGE);
- for (i = 0; i < nr; i++) {
- struct xen_remove_from_physmap xrp;
- unsigned long pfn;
+ for (i = 0; i < nr_page; i++) {
+ /* unmap_gfn guarantees ret == 0 */
+ BUG_ON(xen_apply_to_page(pages[i], unmap_gfn, &nr));
+ }
- pfn = page_to_pfn(pages[i]);
+ /* We should have consume every xen page */
+ BUG_ON(nr != 0);
- 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
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