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xen: privcmd: support autotranslated physmap guests.
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PVH and ARM only support the batch interface. To map a foreign page to
a process, the PFN must be allocated and the autotranslated 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.

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
[v1: Fix up privcmd_close]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[v2: used for ARM too]
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Mukesh Rathor authored and Ian Campbell committed Nov 29, 2012
1 parent 9a032e3 commit d71f513
Showing 1 changed file with 67 additions and 2 deletions.
69 changes: 67 additions & 2 deletions drivers/xen/privcmd.c
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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
Expand All @@ -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;
Expand Down Expand Up @@ -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)
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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",
Expand All @@ -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
};

Expand All @@ -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 = {
Expand Down

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