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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] xen/privcmd: add PRIVCMD_MMAPBATCH_V2 ioctl
On Aug 29, 2012, at 9:15 AM, David Vrabel wrote:
> 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 | 78 +++++++++++++++++++++++++++++++++++++-----------
> include/xen/privcmd.h | 21 ++++++++++++-
> 2 files changed, 80 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index ccee0f1..ddd32cf 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -248,18 +248,23 @@ 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;
> + int *err = data;
Am I missing something or is there an aliasing here? Both mfnp and err point to
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) {
> + *err = ret;
> + if (st->err == 0 || st->err == -ENOENT)
> + st->err = ret;
This will unset -ENOENT if a frame after an ENOENT error fails differently.
> }
> st->va += PAGE_SIZE;
>
> @@ -268,18 +273,30 @@ static int mmap_batch_fn(void *data, void *state)
>
> static int mmap_return_errors(void *data, void *state)
> {
> - xen_pfn_t *mfnp = data;
> + int *err = data;
> struct mmap_batch_state *st = state;
> + int ret;
> +
> + if (st->user_err)
> + return __put_user(*err, st->user_err++);
> + else {
> + xen_pfn_t mfn;
>
> - return put_user(*mfnp, st->user++);
> + 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 +306,32 @@ 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);
> + (xen_pfn_t *)m.arr);
>
> if (ret || list_empty(&pagelist))
> goto out;
> @@ -325,12 +359,16 @@ 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.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);
The callback now maps data to err (instead of mfnp … but I see no change to the
gather_array other than a cast …am I missing something?
Thanks
Andres
> + if (!ret)
> + ret = state.err;
> + } else if (m.err)
> + __clear_user(m.err, m.num * sizeof(*m.err));
>
> out:
> free_page_list(&pagelist);
> @@ -354,7 +392,11 @@ 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..37e5255 100644
> --- a/include/xen/privcmd.h
> +++ b/include/xen/privcmd.h
> @@ -59,13 +59,30 @@ 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 if all pages were mapped successfully. -ENOENT if all
> + * failed mappings returned -ENOENT, otherwise the error code of the
> + * first failed mapping.
> */
> #define IOCTL_PRIVCMD_HYPERCALL \
> _IOC(_IOC_NONE, 'P', 0, sizeof(struct privcmd_hypercall))
> @@ -73,5 +90,7 @@ 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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