[PATCH 3/3] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl

[David Vrabel <david.vrabel@citrix.com>]

From: David Vrabel <david.vrabel@citrix.com>

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@citrix.com>
---
 drivers/xen/privcmd.c |   54 +++++++++++++++++++++++++++++++++++++++----------
 include/xen/privcmd.h |   10 +++++++++
 2 files changed, 53 insertions(+), 11 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index f8c1b6d..4f97160 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -248,7 +248,8 @@ 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)
@@ -275,34 +276,58 @@ static int mmap_return_errors(void *data, void *state)
 {
 	xen_pfn_t *mfnp = data;
 	struct mmap_batch_state *st = state;
+	int ret = 0;
 
-	return put_user(*mfnp, st->user++);
+	if (st->user_err) {
+		if ((*mfnp & 0xf0000000U) == 0xf0000000U)
+			ret = -ENOENT;
+		else if ((*mfnp & 0xf0000000U) == 0x80000000U)
+			ret = -EINVAL;
+		else
+			ret = 0;
+		return __put_user(ret, st->user_err);
+	} else
+		return __put_user(*mfnp, 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;
 	LIST_HEAD(pagelist);
 	struct mmap_batch_state state;
 
+	printk("%s(%d)\n", __func__, version);
+
 	if (!xen_initial_domain())
 		return -EPERM;
 
-	if (copy_from_user(&m, udata, sizeof(m)))
-		return -EFAULT;
+	if (version == 1) {
+		if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch)))
+			return -EFAULT;
+		if (!access_ok(VERIFY_WRITE, m.arr, m.num * sizeof(*m.arr)))
+			return -EFAULT;
+		m.err = NULL;
+	} else {
+		if (copy_from_user(&m, udata, sizeof(struct privcmd_mmapbatch_v2)))
+			return -EFAULT;
+		if (!access_ok(VERIFY_READ, m.arr, m.num * sizeof(*m.arr)))
+			return -EFAULT;
+		if (!access_ok(VERIFY_WRITE, m.err, m.num * (sizeof(*m.err))))
+			return -EFAULT;
+	}
 
 	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);
+			   (xen_pfn_t *)m.arr);
 
 	if (ret || list_empty(&pagelist))
 		goto out;
@@ -331,10 +356,11 @@ static long privcmd_ioctl_mmap_batch(void __user *udata)
 	up_write(&mm->mmap_sem);
 
 	if (state.err > 0) {
-		state.user = m.arr;
+		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);
 	}
 
 out:
@@ -359,7 +385,13 @@ 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);
+		printk("%s() batch ret = %d\n", __func__, ret);
+		break;
+
+	case IOCTL_PRIVCMD_MMAPBATCH_V2:
+		ret = privcmd_ioctl_mmap_batch(udata, 2);
+		printk("%s() batch ret = %d\n", __func__, ret);
 		break;
 
 	default:
diff --git a/include/xen/privcmd.h b/include/xen/privcmd.h
index 17857fb..9fa27c4 100644
--- a/include/xen/privcmd.h
+++ b/include/xen/privcmd.h
@@ -62,6 +62,14 @@ struct privcmd_mmapbatch {
 	xen_pfn_t __user *arr; /* array of mfns - top nibble set on err */
 };
 
+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
@@ -73,5 +81,7 @@ 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