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author | Andres Lagar-Cavilla <andres@lagarcavilla.org> | 2013-08-23 18:10:06 +0100 |
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committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-08-30 08:44:53 -0400 |
commit | a5deabe0e62203350369020687c3fc3b7445a0d0 (patch) | |
tree | c336f20e2618949cd250aae388060baaef4182df /drivers/xen/privcmd.c | |
parent | 669b0ae961e87c824233475e987b2d39996d4849 (diff) | |
download | linux-a5deabe0e62203350369020687c3fc3b7445a0d0.tar.gz linux-a5deabe0e62203350369020687c3fc3b7445a0d0.tar.bz2 linux-a5deabe0e62203350369020687c3fc3b7445a0d0.zip |
Xen: Fix retry calls into PRIVCMD_MMAPBATCH*.
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.
Permit subsequent calls to update a sub-range of the VMA, iff nothing
is yet mapped in that range.
Since it is now valid to call PRIVCMD_MMAPBATCH* multiple times, only
set vma->vm_private_data if the parameters are valid and (if
necessary) the pages for the auto_translated_physmap case have been
allocated. This prevents subsequent calls from incorrectly entering
the 'retry' path when there are no pages allocated etc.
Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/xen/privcmd.c')
-rw-r--r-- | drivers/xen/privcmd.c | 83 |
1 files changed, 63 insertions, 20 deletions
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c index f8e5dd701ecb..8e74590fa1bb 100644 --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -43,9 +43,10 @@ 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_vma_range_is_mapped( + struct vm_area_struct *vma, + unsigned long addr, + unsigned long nr_pages); static long privcmd_ioctl_hypercall(void __user *udata) { @@ -225,9 +226,9 @@ static long privcmd_ioctl_mmap(void __user *udata) vma = find_vma(mm, msg->va); rc = -EINVAL; - if (!vma || (msg->va != vma->vm_start) || - !privcmd_enforce_singleshot_mapping(vma)) + if (!vma || (msg->va != vma->vm_start) || vma->vm_private_data) goto out_up; + vma->vm_private_data = PRIV_VMA_LOCKED; } state.va = vma->vm_start; @@ -358,7 +359,7 @@ static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs) kfree(pages); return -ENOMEM; } - BUG_ON(vma->vm_private_data != PRIV_VMA_LOCKED); + BUG_ON(vma->vm_private_data != NULL); vma->vm_private_data = pages; return 0; @@ -421,19 +422,43 @@ 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)) { - up_write(&mm->mmap_sem); + vma->vm_ops != &privcmd_vm_ops) { ret = -EINVAL; - goto out; + goto out_unlock; } - if (xen_feature(XENFEAT_auto_translated_physmap)) { - ret = alloc_empty_pages(vma, m.num); - if (ret < 0) { - up_write(&mm->mmap_sem); - goto out; + + /* + * Caller must either: + * + * Map the whole VMA range, which will also allocate all the + * pages required for the auto_translated_physmap case. + * + * Or + * + * Map unmapped holes left from a previous map attempt (e.g., + * because those foreign frames were previously paged out). + */ + if (vma->vm_private_data == NULL) { + if (m.addr != vma->vm_start || + m.addr + (nr_pages << PAGE_SHIFT) != vma->vm_end) { + ret = -EINVAL; + goto out_unlock; + } + if (xen_feature(XENFEAT_auto_translated_physmap)) { + ret = alloc_empty_pages(vma, m.num); + if (ret < 0) + goto out_unlock; + } else + vma->vm_private_data = PRIV_VMA_LOCKED; + } else { + if (m.addr < vma->vm_start || + m.addr + (nr_pages << PAGE_SHIFT) > vma->vm_end) { + ret = -EINVAL; + goto out_unlock; + } + if (privcmd_vma_range_is_mapped(vma, m.addr, nr_pages)) { + ret = -EINVAL; + goto out_unlock; } } @@ -466,8 +491,11 @@ static long privcmd_ioctl_mmap_batch(void __user *udata, int version) out: free_page_list(&pagelist); - return ret; + +out_unlock: + up_write(&mm->mmap_sem); + goto out; } static long privcmd_ioctl(struct file *file, @@ -540,9 +568,24 @@ static int privcmd_mmap(struct file *file, struct vm_area_struct *vma) return 0; } -static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma) +/* + * 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 is_mapped_fn(pte_t *pte, struct page *pmd_page, + unsigned long addr, void *data) +{ + return pte_none(*pte) ? 0 : -EBUSY; +} + +static int privcmd_vma_range_is_mapped( + struct vm_area_struct *vma, + unsigned long addr, + unsigned long nr_pages) { - return !cmpxchg(&vma->vm_private_data, NULL, PRIV_VMA_LOCKED); + return apply_to_page_range(vma->vm_mm, addr, nr_pages << PAGE_SHIFT, + is_mapped_fn, NULL) != 0; } const struct file_operations xen_privcmd_fops = { |