# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1179998045 -3600
# Node ID 46095d5a59a9d268c247b2b1bf747024759b1f8e
# Parent 17f6163ae930c007d13abc1e3dbc06a624fb5a21
blktap: Small changes to blktap + add a hook to clear ptes on implicit release
of VMAs.
* free memory on release
* invalidate p2m entry when unmapping grants
* check for alloc failure of idx_map
* add DONTCOPY vma flag
* hook for clearing ptes when a vma is freed by the kernel
From: Geoffrey Lefebvre <geoffrey@xxxxxxxxx>
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c | 117 ++++++++++++++++++++++-
1 files changed, 115 insertions(+), 2 deletions(-)
diff -r 17f6163ae930 -r 46095d5a59a9
linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c
--- a/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c Thu May 24 09:54:03
2007 +0100
+++ b/linux-2.6-xen-sparse/drivers/xen/blktap/blktap.c Thu May 24 10:14:05
2007 +0100
@@ -269,6 +269,16 @@ static inline int GET_NEXT_REQ(unsigned
return INVALID_REQ;
}
+static inline int OFFSET_TO_USR_IDX(int offset)
+{
+ return offset / BLKIF_MAX_SEGMENTS_PER_REQUEST;
+}
+
+static inline int OFFSET_TO_SEG(int offset)
+{
+ return offset % BLKIF_MAX_SEGMENTS_PER_REQUEST;
+}
+
#define BLKTAP_INVALID_HANDLE(_g) \
(((_g->kernel) == INVALID_GRANT_HANDLE) && \
@@ -295,8 +305,90 @@ static struct page *blktap_nopage(struct
return NOPAGE_SIGBUS;
}
+static pte_t blktap_clear_pte(struct vm_area_struct *vma,
+ unsigned long uvaddr,
+ pte_t *ptep, int is_fullmm)
+{
+ pte_t copy = *ptep;
+ tap_blkif_t *info;
+ int offset, seg, usr_idx, pending_idx, mmap_idx;
+ unsigned long uvstart = vma->vm_start + (RING_PAGES << PAGE_SHIFT);
+ unsigned long kvaddr;
+ struct page **map;
+ struct page *pg;
+ struct grant_handle_pair *khandle;
+ struct gnttab_unmap_grant_ref unmap[2];
+ int count = 0;
+ static int print_warning = 1;
+
+ /* Print a warning message once, if the hook gets called. */
+ if (print_warning) {
+ WPRINTK("Clear pte hook called!\n");
+ print_warning = 0;
+ }
+
+ /*
+ * If the address is before the start of the grant mapped region or
+ * if vm_file is NULL (meaning mmap failed and we have nothing to do)
+ */
+ if (uvaddr < uvstart || vma->vm_file == NULL)
+ return copy;
+
+ info = vma->vm_file->private_data;
+ map = vma->vm_private_data;
+
+ /* TODO Should these be changed to if statements? */
+ BUG_ON(!info);
+ BUG_ON(!info->idx_map);
+ BUG_ON(!map);
+
+ offset = (int) ((uvaddr - uvstart) >> PAGE_SHIFT);
+ usr_idx = OFFSET_TO_USR_IDX(offset);
+ seg = OFFSET_TO_SEG(offset);
+
+ pending_idx = MASK_PEND_IDX(ID_TO_IDX(info->idx_map[usr_idx]));
+ mmap_idx = ID_TO_MIDX(info->idx_map[usr_idx]);
+
+ kvaddr = idx_to_kaddr(mmap_idx, pending_idx, seg);
+ pg = pfn_to_page(__pa(kvaddr) >> PAGE_SHIFT);
+ ClearPageReserved(pg);
+ map[offset] = NULL;
+
+ khandle = &pending_handle(mmap_idx, pending_idx, seg);
+
+ if (khandle->kernel != INVALID_GRANT_HANDLE) {
+ gnttab_set_unmap_op(&unmap[count], kvaddr,
+ GNTMAP_host_map, khandle->kernel);
+ count++;
+
+ set_phys_to_machine(__pa(kvaddr) >> PAGE_SHIFT,
+ INVALID_P2M_ENTRY);
+ }
+
+ if (khandle->user != INVALID_GRANT_HANDLE) {
+ BUG_ON(xen_feature(XENFEAT_auto_translated_physmap));
+
+ gnttab_set_unmap_op(&unmap[count], virt_to_machine(ptep),
+ GNTMAP_host_map
+ | GNTMAP_application_map
+ | GNTMAP_contains_pte,
+ khandle->user);
+ count++;
+ }
+
+ if (count) {
+ BLKTAP_INVALIDATE_HANDLE(khandle);
+ if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
+ unmap, count))
+ BUG();
+ }
+
+ return copy;
+}
+
struct vm_operations_struct blktap_vm_ops = {
nopage: blktap_nopage,
+ zap_pte: blktap_clear_pte,
};
/******************************************************************
@@ -477,6 +569,9 @@ static int blktap_open(struct inode *ino
info->idx_map = kmalloc(sizeof(unsigned long) * MAX_PENDING_REQS,
GFP_KERNEL);
+ if (info->idx_map == NULL)
+ goto fail_nomem;
+
if (idx > 0) {
init_waitqueue_head(&info->wait);
for (i = 0; i < MAX_PENDING_REQS; i++)
@@ -510,16 +605,25 @@ static int blktap_release(struct inode *
zap_page_range(
info->vma, info->vma->vm_start,
info->vma->vm_end - info->vma->vm_start, NULL);
+
+ kfree(info->vma->vm_private_data);
+
info->vma = NULL;
}
-
+
+ if (info->idx_map) {
+ kfree(info->idx_map);
+ info->idx_map = NULL;
+ }
+
if ( (info->status != CLEANSHUTDOWN) && (info->blkif != NULL) ) {
if (info->blkif->xenblkd != NULL) {
kthread_stop(info->blkif->xenblkd);
info->blkif->xenblkd = NULL;
}
info->status = CLEANSHUTDOWN;
- }
+ }
+
return 0;
}
@@ -590,6 +694,11 @@ static int blktap_mmap(struct file *filp
vma->vm_private_data = map;
vma->vm_flags |= VM_FOREIGN;
+ vma->vm_flags |= VM_DONTCOPY;
+
+#ifdef CONFIG_X86
+ vma->vm_mm->context.has_foreign_mappings = 1;
+#endif
info->vma = vma;
info->ring_ok = 1;
@@ -885,6 +994,10 @@ static void fast_flush_area(pending_req_
idx_to_kaddr(mmap_idx, k_idx, i),
GNTMAP_host_map, khandle->kernel);
invcount++;
+
+ set_phys_to_machine(
+ __pa(idx_to_kaddr(mmap_idx, k_idx, i))
+ >> PAGE_SHIFT, INVALID_P2M_ENTRY);
}
if (khandle->user != INVALID_GRANT_HANDLE) {
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