[Xen-devel] [PATCH 3/3] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl

[David Vrabel <david.vrabel@xxxxxxxxxx>]

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 |   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


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