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Date:	Thu, 18 Oct 2012 12:52:05 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Mukesh Rathor <mukesh.rathor@...cle.com>
CC:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	"Xen-devel@...ts.xensource.com" <Xen-devel@...ts.xensource.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 6/6]: PVH:privcmd changes.

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@...cle.com>

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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