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Message-ID: <alpine.DEB.2.02.1210221422310.2689@kaball.uk.xensource.com>
Date: Mon, 22 Oct 2012 14:22:36 +0100
From: Stefano Stabellini <stefano.stabellini@...citrix.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>,
"mukesh.rathor@...cle.com" <mukesh.rathor@...cle.com>,
Ian Campbell <Ian.Campbell@...rix.com>,
Stefano Stabellini <Stefano.Stabellini@...citrix.com>
Subject: Re: [PATCH 6/6] xen/pvh: /dev/xen/privcmd changes.
On Sat, 20 Oct 2012, Konrad Rzeszutek Wilk wrote:
> From: Mukesh Rathor <mukesh.rathor@...cle.com>
>
> PVH only supports the batch interface. To map a foreign page to a process,
> the PFN must be allocated and 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>
> [v1: Fix up privcmd_close]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Acked-by: Stefano Stabellini <stefano.stabellini@...citrix.com>
> 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 b612267..b9d0898 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->vm_private_data;
> + int numpgs = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> +
> + if (!xen_feature(XENFEAT_auto_translated_physmap || !numpgs || !pages))
> + 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
> };
>
> @@ -466,7 +531,7 @@ 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 = {
> --
> 1.7.7.6
>
--
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