Re: [Xen-devel] [PATCH V3 6/6]: PVH:privcmd changes.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 18 Oct 2012, Mukesh Rathor wrote:
> PVH: privcmd changes. PVH only supports the batch interface. To map a foreign 
> page to a process, pfn must be allocated. PVH path uses ballooning for that 
> purpose. The returned pfn is then mapped to the foreign page. 
> xen_unmap_domain_mfn_range() is introduced to unmap these pages via the 
> privcmd close call.
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>

this one also looks all right


>  drivers/xen/privcmd.c |   69 +++++++++++++++++++++++++++++++++++++++++++++++-
>  1 files changed, 67 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 63d9ee8..835166a 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -33,11 +33,14 @@
>  #include <xen/features.h>
>  #include <xen/page.h>
>  #include <xen/xen-ops.h>
> +#include <xen/balloon.h>
>  
>  #include "privcmd.h"
>  
>  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
> @@ -199,6 +202,10 @@ static long privcmd_ioctl_mmap(void __user *udata)
>       if (!xen_initial_domain())
>               return -EPERM;
>  
> +     /* We only support privcmd_ioctl_mmap_batch for auto translated. */
> +     if (xen_feature(XENFEAT_auto_translated_physmap))
> +             return -ENOSYS;
> +
>       if (copy_from_user(&mmapcmd, udata, sizeof(mmapcmd)))
>               return -EFAULT;
>  
> @@ -246,6 +253,7 @@ struct mmap_batch_state {
>       domid_t domain;
>       unsigned long va;
>       struct vm_area_struct *vma;
> +     int index;
>       /* A tristate:
>        *      0 for no errors
>        *      1 if at least one error has happened (and no
> @@ -260,15 +268,24 @@ struct mmap_batch_state {
>       xen_pfn_t __user *user_mfn;
>  };
>  
> +/* auto translated dom0 note: if domU being created is PV, then mfn is
> + * mfn(addr on bus). If it's auto xlated, then mfn is pfn (input to HAP).
> + */
>  static int mmap_batch_fn(void *data, void *state)
>  {
>       xen_pfn_t *mfnp = data;
>       struct mmap_batch_state *st = state;
> +     struct vm_area_struct *vma = st->vma;
> +     struct page **pages = vma->vm_private_data;
> +     struct page *cur_page = NULL;
>       int ret;
>  
> +     if (xen_feature(XENFEAT_auto_translated_physmap))
> +             cur_page = pages[st->index++];
> +
>       ret = xen_remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, *mfnp, 1,
>                                        st->vma->vm_page_prot, st->domain,
> -                                      NULL);
> +                                      &cur_page);
>  
>       /* Store error code for second pass. */
>       *(st->err++) = ret;
> @@ -304,6 +321,32 @@ static int mmap_return_errors_v1(void *data, void *state)
>       return __put_user(*mfnp, st->user_mfn++);
>  }
>  
> +/* Allocate pfns that are then mapped with gmfns from foreign domid. Update
> + * the vma with the page info to use later.
> + * Returns: 0 if success, otherwise -errno
> + */
> +static int alloc_empty_pages(struct vm_area_struct *vma, int numpgs)
> +{
> +     int rc;
> +     struct page **pages;
> +
> +     pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL);
> +     if (pages == NULL)
> +             return -ENOMEM;
> +
> +     rc = alloc_xenballooned_pages(numpgs, pages, 0);
> +     if (rc != 0) {
> +             pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__,
> +                     numpgs, rc);
> +             kfree(pages);
> +             return -ENOMEM;
> +     }
> +     BUG_ON(vma->vm_private_data != PRIV_VMA_LOCKED);
> +     vma->vm_private_data = pages;
> +
> +     return 0;
> +}
> +
>  static struct vm_operations_struct privcmd_vm_ops;
>  
>  static long privcmd_ioctl_mmap_batch(void __user *udata, int version)
> @@ -371,10 +414,18 @@ static long privcmd_ioctl_mmap_batch(void __user 
> *udata, int version)
>               up_write(&mm->mmap_sem);
>               goto out;
>       }
> +     if (xen_feature(XENFEAT_auto_translated_physmap)) {
> +             ret = alloc_empty_pages(vma, m.num);
> +             if (ret < 0) {
> +                     up_write(&mm->mmap_sem);
> +                     goto out;
> +             }
> +     }
>  
>       state.domain        = m.dom;
>       state.vma           = vma;
>       state.va            = m.addr;
> +     state.index         = 0;
>       state.global_error  = 0;
>       state.err           = err_array;
>  
> @@ -439,6 +490,19 @@ static long privcmd_ioctl(struct file *file,
>       return ret;
>  }
>  
> +static void privcmd_close(struct vm_area_struct *vma)
> +{
> +     struct page **pages = vma ? vma->vm_private_data : NULL;
> +     int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> +
> +     if (!pages || !numpgs || !xen_feature(XENFEAT_auto_translated_physmap))
> +             return;
> +
> +     xen_unmap_domain_mfn_range(vma, numpgs, pages);
> +     free_xenballooned_pages(numpgs, pages);
> +     kfree(pages);
> +}
> +
>  static int privcmd_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  {
>       printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
> @@ -449,6 +513,7 @@ static int privcmd_fault(struct vm_area_struct *vma, 
> struct vm_fault *vmf)
>  }
>  
>  static struct vm_operations_struct privcmd_vm_ops = {
> +     .close = privcmd_close,
>       .fault = privcmd_fault
>  };
>  
> @@ -465,7 +530,7 @@ static int privcmd_mmap(struct file *file, struct 
> vm_area_struct *vma)
>  
>  static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma)
>  {
> -     return (xchg(&vma->vm_private_data, (void *)1) == NULL);
> +     return !cmpxchg(&vma->vm_private_data, NULL, PRIV_VMA_LOCKED);
>  }
>  
>  const struct file_operations xen_privcmd_fops = {
> -- 
> 1.7.2.3
> 
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