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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 14/17] [V3]PVH xen: Add and remove foreign pages
In this patch, a new function, xenmem_add_foreign_to_pmap(), is added
to map pages from foreign guest into current dom0 for domU creation.
Also, allow XENMEM_remove_from_physmap to remove p2m_map_foreign
pages. Note, in this path, we must release the refcount that was taken
during the map phase.
Changes in V2:
- Move the XENMEM_remove_from_physmap changes here instead of prev patch
- Move grant changes from this to one of the next patches.
- In xenmem_add_foreign_to_pmap(), do locked get_gfn
- Fail the mappings for qemu mapping pages for memory not there.
Changes in V3:
- remove mmio pages.
- remove unrelated changes.
- cleanup both add and remove.
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
xen/arch/x86/mm.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
xen/common/memory.c | 38 +++++++++++++++++++++---
2 files changed, 113 insertions(+), 5 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 7b539cf..06fa3fd 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4266,6 +4266,78 @@ static int handle_iomem_range(unsigned long s, unsigned
long e, void *p)
return 0;
}
+/*
+ * Add frames from foreign domain to current domain's physmap. Similar to
+ * XENMAPSPACE_gmfn but the frame is foreign being mapped into current,
+ * and is not removed from foreign domain.
+ * Usage: libxl on pvh dom0 creating a guest and doing privcmd_ioctl_mmap.
+ * Side Effect: the mfn for fgfn will be refcounted so it is not lost
+ * while mapped here. The refcnt is released in do_memory_op()
+ * via XENMEM_remove_from_physmap.
+ * Returns: 0 ==> success
+ */
+static int xenmem_add_foreign_to_pmap(domid_t foreign_domid,
+ unsigned long fgfn, unsigned long gpfn)
+{
+ p2m_type_t p2mt, p2mt_prev;
+ int rc = 0;
+ unsigned long prev_mfn, mfn = 0;
+ struct domain *fdom, *currd = current->domain;
+ struct page_info *page = NULL;
+
+ if ( currd->domain_id == foreign_domid || foreign_domid == DOMID_SELF ||
+ !is_pvh_domain(currd) )
+ return -EINVAL;
+
+ if ( !IS_PRIV(currd) || (fdom = get_pg_owner(foreign_domid)) == NULL )
+ return -EPERM;
+
+ /* following will take a refcnt on the mfn */
+ page = get_page_from_gfn(fdom, fgfn, &p2mt, P2M_ALLOC);
+ if ( !page || !p2m_is_valid(p2mt) )
+ {
+ if ( page )
+ put_page(page);
+ put_pg_owner(fdom);
+ return -EINVAL;
+ }
+ mfn = page_to_mfn(page);
+
+ /* Remove previously mapped page if it is present. */
+ prev_mfn = mfn_x(get_gfn(currd, gpfn, &p2mt_prev));
+ if ( mfn_valid(prev_mfn) )
+ {
+ if ( is_xen_heap_mfn(prev_mfn) )
+ /* Xen heap frames are simply unhooked from this phys slot */
+ guest_physmap_remove_page(currd, gpfn, prev_mfn, 0);
+ else
+ /* Normal domain memory is freed, to avoid leaking memory. */
+ guest_remove_page(currd, gpfn);
+ }
+ /*
+ * Create the new mapping. Can't use guest_physmap_add_page() because it
+ * will update the m2p table which will result in mfn -> gpfn of dom0
+ * and not fgfn of domU.
+ */
+ if ( set_foreign_p2m_entry(currd, gpfn, _mfn(mfn)) == 0 )
+ {
+ dprintk(XENLOG_WARNING,
+ "guest_physmap_add_page failed. gpfn:%lx mfn:%lx fgfn:%lx\n",
+ gpfn, mfn, fgfn);
+ put_page(page);
+ rc = -EINVAL;
+ }
+
+ /*
+ * We must do this put_gfn after set_foreign_p2m_entry so another cpu
+ * doesn't populate the gpfn before us.
+ */
+ put_gfn(currd, gpfn);
+
+ put_pg_owner(fdom);
+ return rc;
+}
+
static int xenmem_add_to_physmap_once(
struct domain *d,
const struct xen_add_to_physmap *xatp,
@@ -4328,6 +4400,14 @@ static int xenmem_add_to_physmap_once(
page = mfn_to_page(mfn);
break;
}
+
+ case XENMAPSPACE_gmfn_foreign:
+ {
+ rc = xenmem_add_foreign_to_pmap(foreign_domid, xatp->idx,
+ xatp->gpfn);
+ return rc;
+ }
+
default:
break;
}
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 68501d1..a321d33 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -675,9 +675,11 @@ long do_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
case XENMEM_remove_from_physmap:
{
+ unsigned long mfn;
struct xen_remove_from_physmap xrfp;
struct page_info *page;
- struct domain *d;
+ struct domain *d, *foreign_dom = NULL;
+ p2m_type_t p2mt, tp;
if ( copy_from_guest(&xrfp, arg, 1) )
return -EFAULT;
@@ -695,11 +697,37 @@ long do_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
domain_lock(d);
- page = get_page_from_gfn(d, xrfp.gpfn, NULL, P2M_ALLOC);
- if ( page )
+ /*
+ * if PVH, the gfn could be mapped to a mfn from foreign domain by the
+ * user space tool during domain creation. We need to check for that,
+ * free it up from the p2m, and release refcnt on it. In such a case,
+ * page would be NULL and the following call would not have refcnt'd
+ * the page. See also xenmem_add_foreign_to_pmap().
+ */
+ page = get_page_from_gfn(d, xrfp.gpfn, &p2mt, P2M_ALLOC);
+
+ if ( page || p2m_is_foreign(p2mt) )
{
- guest_physmap_remove_page(d, xrfp.gpfn, page_to_mfn(page), 0);
- put_page(page);
+ if ( page )
+ mfn = page_to_mfn(page);
+ else
+ {
+ mfn = mfn_x(get_gfn_query(d, xrfp.gpfn, &tp));
+ foreign_dom = page_get_owner(mfn_to_page(mfn));
+ ASSERT(is_pvh_domain(d));
+ ASSERT(d != foreign_dom);
+ ASSERT(p2m_is_foreign(tp));
+ }
+
+ guest_physmap_remove_page(d, xrfp.gpfn, mfn, 0);
+ if (page)
+ put_page(page);
+
+ if ( p2m_is_foreign(p2mt) )
+ {
+ put_page(mfn_to_page(mfn));
+ put_gfn(d, xrfp.gpfn);
+ }
}
else
rc = -ENOENT;
--
1.7.2.3
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