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Merge tag 'for-linus-4.18-rc2-tag' of git://git.kernel.org/pub/scm/li…
…nux/kernel/git/xen/tip
Pull xen fixes from Juergen Gross:
"This contains the following fixes/cleanups:
- the removal of a BUG_ON() which wasn't necessary and which could
trigger now due to a recent change
- a correction of a long standing bug happening very rarely in Xen
dom0 when a hypercall buffer from user land was not accessible by
the hypervisor for very short periods of time due to e.g. page
migration or compaction
- usage of EXPORT_SYMBOL_GPL() instead of EXPORT_SYMBOL() in a
Xen-related driver (no breakage possible as using those symbols
without others already exported via EXPORT-SYMBOL_GPL() wouldn't
make any sense)
- a simplification for Xen PVH or Xen ARM guests
- some additional error handling for callers of xenbus_printf()"
* tag 'for-linus-4.18-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
xen: Remove unnecessary BUG_ON from __unbind_from_irq()
xen: add new hypercall buffer mapping device
xen/scsiback: add error handling for xenbus_printf
scsi: xen-scsifront: add error handling for xenbus_printf
xen/grant-table: Export gnttab_{alloc|free}_pages as GPL
xen: add error handling for xenbus_printf
xen: share start flags between PV and PVH- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,210 @@ | ||
| // SPDX-License-Identifier: GPL-2.0 OR MIT | ||
|
|
||
| /****************************************************************************** | ||
| * privcmd-buf.c | ||
| * | ||
| * Mmap of hypercall buffers. | ||
| * | ||
| * Copyright (c) 2018 Juergen Gross | ||
| */ | ||
|
|
||
| #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt | ||
|
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| #include <linux/kernel.h> | ||
| #include <linux/module.h> | ||
| #include <linux/list.h> | ||
| #include <linux/miscdevice.h> | ||
| #include <linux/mm.h> | ||
| #include <linux/slab.h> | ||
|
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| #include "privcmd.h" | ||
|
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| MODULE_LICENSE("GPL"); | ||
|
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| static unsigned int limit = 64; | ||
| module_param(limit, uint, 0644); | ||
| MODULE_PARM_DESC(limit, "Maximum number of pages that may be allocated by " | ||
| "the privcmd-buf device per open file"); | ||
|
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||
| struct privcmd_buf_private { | ||
| struct mutex lock; | ||
| struct list_head list; | ||
| unsigned int allocated; | ||
| }; | ||
|
|
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| struct privcmd_buf_vma_private { | ||
| struct privcmd_buf_private *file_priv; | ||
| struct list_head list; | ||
| unsigned int users; | ||
| unsigned int n_pages; | ||
| struct page *pages[]; | ||
| }; | ||
|
|
||
| static int privcmd_buf_open(struct inode *ino, struct file *file) | ||
| { | ||
| struct privcmd_buf_private *file_priv; | ||
|
|
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| file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL); | ||
| if (!file_priv) | ||
| return -ENOMEM; | ||
|
|
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| mutex_init(&file_priv->lock); | ||
| INIT_LIST_HEAD(&file_priv->list); | ||
|
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| file->private_data = file_priv; | ||
|
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| return 0; | ||
| } | ||
|
|
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| static void privcmd_buf_vmapriv_free(struct privcmd_buf_vma_private *vma_priv) | ||
| { | ||
| unsigned int i; | ||
|
|
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| vma_priv->file_priv->allocated -= vma_priv->n_pages; | ||
|
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| list_del(&vma_priv->list); | ||
|
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| for (i = 0; i < vma_priv->n_pages; i++) | ||
| if (vma_priv->pages[i]) | ||
| __free_page(vma_priv->pages[i]); | ||
|
|
||
| kfree(vma_priv); | ||
| } | ||
|
|
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| static int privcmd_buf_release(struct inode *ino, struct file *file) | ||
| { | ||
| struct privcmd_buf_private *file_priv = file->private_data; | ||
| struct privcmd_buf_vma_private *vma_priv; | ||
|
|
||
| mutex_lock(&file_priv->lock); | ||
|
|
||
| while (!list_empty(&file_priv->list)) { | ||
| vma_priv = list_first_entry(&file_priv->list, | ||
| struct privcmd_buf_vma_private, | ||
| list); | ||
| privcmd_buf_vmapriv_free(vma_priv); | ||
| } | ||
|
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| mutex_unlock(&file_priv->lock); | ||
|
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| kfree(file_priv); | ||
|
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| return 0; | ||
| } | ||
|
|
||
| static void privcmd_buf_vma_open(struct vm_area_struct *vma) | ||
| { | ||
| struct privcmd_buf_vma_private *vma_priv = vma->vm_private_data; | ||
|
|
||
| if (!vma_priv) | ||
| return; | ||
|
|
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| mutex_lock(&vma_priv->file_priv->lock); | ||
| vma_priv->users++; | ||
| mutex_unlock(&vma_priv->file_priv->lock); | ||
| } | ||
|
|
||
| static void privcmd_buf_vma_close(struct vm_area_struct *vma) | ||
| { | ||
| struct privcmd_buf_vma_private *vma_priv = vma->vm_private_data; | ||
| struct privcmd_buf_private *file_priv; | ||
|
|
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| if (!vma_priv) | ||
| return; | ||
|
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| file_priv = vma_priv->file_priv; | ||
|
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| mutex_lock(&file_priv->lock); | ||
|
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| vma_priv->users--; | ||
| if (!vma_priv->users) | ||
| privcmd_buf_vmapriv_free(vma_priv); | ||
|
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| mutex_unlock(&file_priv->lock); | ||
| } | ||
|
|
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| static vm_fault_t privcmd_buf_vma_fault(struct vm_fault *vmf) | ||
| { | ||
| pr_debug("fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n", | ||
| vmf->vma, vmf->vma->vm_start, vmf->vma->vm_end, | ||
| vmf->pgoff, (void *)vmf->address); | ||
|
|
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| return VM_FAULT_SIGBUS; | ||
| } | ||
|
|
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| static const struct vm_operations_struct privcmd_buf_vm_ops = { | ||
| .open = privcmd_buf_vma_open, | ||
| .close = privcmd_buf_vma_close, | ||
| .fault = privcmd_buf_vma_fault, | ||
| }; | ||
|
|
||
| static int privcmd_buf_mmap(struct file *file, struct vm_area_struct *vma) | ||
| { | ||
| struct privcmd_buf_private *file_priv = file->private_data; | ||
| struct privcmd_buf_vma_private *vma_priv; | ||
| unsigned long count = vma_pages(vma); | ||
| unsigned int i; | ||
| int ret = 0; | ||
|
|
||
| if (!(vma->vm_flags & VM_SHARED) || count > limit || | ||
| file_priv->allocated + count > limit) | ||
| return -EINVAL; | ||
|
|
||
| vma_priv = kzalloc(sizeof(*vma_priv) + count * sizeof(void *), | ||
| GFP_KERNEL); | ||
| if (!vma_priv) | ||
| return -ENOMEM; | ||
|
|
||
| vma_priv->n_pages = count; | ||
| count = 0; | ||
| for (i = 0; i < vma_priv->n_pages; i++) { | ||
| vma_priv->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO); | ||
| if (!vma_priv->pages[i]) | ||
| break; | ||
| count++; | ||
| } | ||
|
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| mutex_lock(&file_priv->lock); | ||
|
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| file_priv->allocated += count; | ||
|
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| vma_priv->file_priv = file_priv; | ||
| vma_priv->users = 1; | ||
|
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| vma->vm_flags |= VM_IO | VM_DONTEXPAND; | ||
| vma->vm_ops = &privcmd_buf_vm_ops; | ||
| vma->vm_private_data = vma_priv; | ||
|
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| list_add(&vma_priv->list, &file_priv->list); | ||
|
|
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| if (vma_priv->n_pages != count) | ||
| ret = -ENOMEM; | ||
| else | ||
| for (i = 0; i < vma_priv->n_pages; i++) { | ||
| ret = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE, | ||
| vma_priv->pages[i]); | ||
| if (ret) | ||
| break; | ||
| } | ||
|
|
||
| if (ret) | ||
| privcmd_buf_vmapriv_free(vma_priv); | ||
|
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| mutex_unlock(&file_priv->lock); | ||
|
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||
| return ret; | ||
| } | ||
|
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||
| const struct file_operations xen_privcmdbuf_fops = { | ||
| .owner = THIS_MODULE, | ||
| .open = privcmd_buf_open, | ||
| .release = privcmd_buf_release, | ||
| .mmap = privcmd_buf_mmap, | ||
| }; | ||
| EXPORT_SYMBOL_GPL(xen_privcmdbuf_fops); | ||
|
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||
| struct miscdevice xen_privcmdbuf_dev = { | ||
| .minor = MISC_DYNAMIC_MINOR, | ||
| .name = "xen/hypercall", | ||
| .fops = &xen_privcmdbuf_fops, | ||
| }; |
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