|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/2] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl
From: David Vrabel <david.vrabel@xxxxxxxxxx>
PRIVCMD_MMAPBATCH_V2 extends PRIVCMD_MMAPBATCH with an additional
field for reporting the error code for every frame that could not be
mapped. libxc prefers PRIVCMD_MMAPBATCH_V2 over PRIVCMD_MMAPBATCH.
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
drivers/xen/privcmd.c | 99 +++++++++++++++++++++++++++++++++++++++---------
include/xen/privcmd.h | 23 +++++++++++-
2 files changed, 102 insertions(+), 20 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index ccee0f1..c0e89e7 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -76,7 +76,7 @@ static void free_page_list(struct list_head *pages)
*/
static int gather_array(struct list_head *pagelist,
unsigned nelem, size_t size,
- void __user *data)
+ const void __user *data)
{
unsigned pageidx;
void *pagedata;
@@ -248,18 +248,37 @@ struct mmap_batch_state {
struct vm_area_struct *vma;
int err;
- xen_pfn_t __user *user;
+ xen_pfn_t __user *user_mfn;
+ int __user *user_err;
};
static int mmap_batch_fn(void *data, void *state)
{
xen_pfn_t *mfnp = data;
struct mmap_batch_state *st = state;
+ int ret;
- if (xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
- st->vma->vm_page_prot, st->domain) < 0) {
- *mfnp |= 0xf0000000U;
- st->err++;
+ ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
+ st->vma->vm_page_prot, st->domain);
+ if (ret < 0) {
+ /*
+ * Error reporting is a mess but userspace relies on
+ * it behaving this way.
+ *
+ * V2 needs to a) return the result of each frame's
+ * remap; and b) return -ENOENT if any frame failed
+ * with -ENOENT.
+ *
+ * In this first pass the error code is saved by
+ * overwriting the mfn and an error is indicated in
+ * st->err.
+ *
+ * The second pass by mmap_return_errors() will write
+ * the error codes to user space and get the right
+ * ioctl return value.
+ */
+ *(int *)mfnp = ret;
+ st->err = ret;
}
st->va += PAGE_SIZE;
@@ -270,16 +289,33 @@ static int mmap_return_errors(void *data, void *state)
{
xen_pfn_t *mfnp = data;
struct mmap_batch_state *st = state;
+ int ret;
+
+ if (st->user_err) {
+ int err = *(int *)mfnp;
+
+ if (err == -ENOENT)
+ st->err = err;
- return put_user(*mfnp, st->user++);
+ return __put_user(err, st->user_err++);
+ } else {
+ xen_pfn_t mfn;
+
+ ret = __get_user(mfn, st->user_mfn);
+ if (ret < 0)
+ return ret;
+
+ mfn |= PRIVCMD_MMAPBATCH_MFN_ERROR;
+ return __put_user(mfn, st->user_mfn++);
+ }
}
static struct vm_operations_struct privcmd_vm_ops;
-static long privcmd_ioctl_mmap_batch(void __user *udata)
+static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
{
int ret;
- struct privcmd_mmapbatch m;
+ struct privcmd_mmapbatch_v2 m;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long nr_pages;
@@ -289,15 +325,31 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
if (!xen_initial_domain())
return -EPERM;
- if (copy_from_user(&m, udata, sizeof(m)))
- return -EFAULT;
+ switch (version) {
+ case 1:
+ if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
+ return -EFAULT;
+ /* Returns per-frame error in m.arr. */
+ m.err = NULL;
+ if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr)))
+ return -EFAULT;
+ break;
+ case 2:
+ if (copy_from_user(&m, udata, sizeof(struct
privcmd_mmapbatch_v2)))
+ return -EFAULT;
+ /* Returns per-frame error code in m.err. */
+ if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err))))
+ return -EFAULT;
+ break;
+ default:
+ return -EINVAL;
+ }
nr_pages = m.num;
if ((m.num <= 0) || (nr_pages > (LONG_MAX >> PAGE_SHIFT)))
return -EINVAL;
- ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t),
- m.arr);
+ ret = gather_array(&pagelist, m.num, sizeof(xen_pfn_t), m.arr);
if (ret || list_empty(&pagelist))
goto out;
@@ -325,12 +377,17 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
up_write(&mm->mmap_sem);
- if (state.err > 0) {
- state.user = m.arr;
+ if (state.err) {
+ state.err = 0;
+ state.user_mfn = (xen_pfn_t *)m.arr;
+ state.user_err = m.err;
ret = traverse_pages(m.num, sizeof(xen_pfn_t),
- &pagelist,
- mmap_return_errors, &state);
- }
+ &pagelist,
+ mmap_return_errors, &state);
+ if (ret >= 0)
+ ret = state.err;
+ } else if (m.err)
+ __clear_user(m.err, m.num * sizeof(*m.err));
out:
free_page_list(&pagelist);
@@ -354,7 +411,11 @@ static long privcmd_ioctl(struct file *file,
break;
case IOCTL_PRIVCMD_MMAPBATCH:
- ret = privcmd_ioctl_mmap_batch(udata);
+ ret = privcmd_ioctl_mmap_batch(udata, 1);
+ break;
+
+ case IOCTL_PRIVCMD_MMAPBATCH_V2:
+ ret = privcmd_ioctl_mmap_batch(udata, 2);
break;
default:
diff --git a/include/xen/privcmd.h b/include/xen/privcmd.h
index 17857fb..f60d75c 100644
--- a/include/xen/privcmd.h
+++ b/include/xen/privcmd.h
@@ -59,13 +59,32 @@ struct privcmd_mmapbatch {
int num; /* number of pages to populate */
domid_t dom; /* target domain */
__u64 addr; /* virtual address */
- xen_pfn_t __user *arr; /* array of mfns - top nibble set on err */
+ xen_pfn_t __user *arr; /* array of mfns - or'd with
+ PRIVCMD_MMAPBATCH_MFN_ERROR on err */
+};
+
+#define PRIVCMD_MMAPBATCH_MFN_ERROR 0xf0000000U
+
+struct privcmd_mmapbatch_v2 {
+ unsigned int num; /* number of pages to populate */
+ domid_t dom; /* target domain */
+ __u64 addr; /* virtual address */
+ const xen_pfn_t __user *arr; /* array of mfns */
+ int __user *err; /* array of error codes */
};
/*
* @cmd: IOCTL_PRIVCMD_HYPERCALL
* @arg: &privcmd_hypercall_t
* Return: Value returned from execution of the specified hypercall.
+ *
+ * @cmd: IOCTL_PRIVCMD_MMAPBATCH_V2
+ * @arg: &struct privcmd_mmapbatch_v2
+ * Return: 0 on success (i.e., arg->err contains valid error codes for
+ * each frame). On an error other than a failed frame remap, -1 is
+ * returned and errno is set to EINVAL, EFAULT etc. As an exception,
+ * if the operation was otherwise successful but any frame failed with
+ * -ENOENT, then -1 is returned and errno is set to ENOENT.
*/
#define IOCTL_PRIVCMD_HYPERCALL \
_IOC(_IOC_NONE, 'P', 0, sizeof(struct privcmd_hypercall))
@@ -73,5 +92,7 @@ struct privcmd_mmapbatch {
_IOC(_IOC_NONE, 'P', 2, sizeof(struct privcmd_mmap))
#define IOCTL_PRIVCMD_MMAPBATCH \
_IOC(_IOC_NONE, 'P', 3, sizeof(struct privcmd_mmapbatch))
+#define IOCTL_PRIVCMD_MMAPBATCH_V2 \
+ _IOC(_IOC_NONE, 'P', 4, sizeof(struct privcmd_mmapbatch_v2))
#endif /* __LINUX_PUBLIC_PRIVCMD_H__ */
--
1.7.2.5
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |