Messages in this thread Patch in this message | | | Subject | Re: [PATCH] Xen: Fix retry calls into PRIVCMD_MMAPBATCH*. | From | Andres Lagar-Cavilla <> | Date | Wed, 31 Jul 2013 23:30:47 -0400 |
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-- Resend as I haven't seen this hit the lists. Maybe some smtp misconfig. Apologies. Also expanded cc --
When a foreign mapper attempts to map guest frames that are paged out, the mapper receives an ENOENT response and will have to try again while a helper process pages the target frame back in.
Gating checks on PRIVCMD_MMAPBATCH* ioctl args were preventing retries of mapping calls.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> --- drivers/xen/privcmd.c | 32 +++++++++++++++++++++++++++----- 1 files changed, 27 insertions(+), 5 deletions(-)
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index f8e5dd7..44a26c6 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -43,9 +43,12 @@ MODULE_LICENSE("GPL");
#define PRIV_VMA_LOCKED ((void *)1)
-#ifndef HAVE_ARCH_PRIVCMD_MMAP static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma); -#endif + +static int privcmd_enforce_singleshot_mapping_granular( + struct vm_area_struct *vma, + unsigned long addr, + unsigned long nr_pages);
static long privcmd_ioctl_hypercall(void __user *udata) { @@ -422,9 +425,9 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) vma = find_vma(mm, m.addr); if (!vma || vma->vm_ops != &privcmd_vm_ops || - (m.addr != vma->vm_start) || - ((m.addr + (nr_pages << PAGE_SHIFT)) != vma->vm_end) || - !privcmd_enforce_singleshot_mapping(vma)) { + (m.addr < vma->vm_start) || + ((m.addr + (nr_pages << PAGE_SHIFT)) > vma->vm_end) || + !privcmd_enforce_singleshot_mapping_granular(vma, m.addr, nr_pages)) { up_write(&mm->mmap_sem); ret = -EINVAL; goto out; @@ -540,11 +543,30 @@ static int privcmd_mmap(struct file *file, struct vm_area_struct *vma) return 0; }
+/* For MMAP */ static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma) { return !cmpxchg(&vma->vm_private_data, NULL, PRIV_VMA_LOCKED); }
+/* For MMAPBATCH*. This allows asserting the singleshot mapping + * on a per pfn/pte basis. Mapping calls that fail with ENOENT + * can be then retried until success. */ +static int enforce_singleshot_mapping_fn(pte_t *pte, struct page *pmd_page, + unsigned long addr, void *data) +{ + return pte_none(*pte) ? 0 : -EBUSY; +} + +static int privcmd_enforce_singleshot_mapping_granular( + struct vm_area_struct *vma, + unsigned long addr, + unsigned long nr_pages) +{ + return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT, + enforce_singleshot_mapping_fn, NULL) == 0; +} + const struct file_operations xen_privcmd_fops = { .owner = THIS_MODULE, .unlocked_ioctl = privcmd_ioctl, -- 1.7.1 >
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