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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [V6 PATCH 6.2/7] pvh dom0: Add and remove foreign pages
On Wed, 11 Dec 2013 01:35:08 +0000
Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> > unsigned long mfn = gmfn_to_mfn(d, gfn);
> >
> > - ASSERT(t == NULL);
> > + ASSERT(*t == INT_MAX);
>
> There is various place where get_page_from_gfn where t == NULL. With
> this solution it will segfault every time.
>
> I would do something like that:
> if (*t)
> t = INT_MAX;
here's updated:
------------
In this patch, a new function, p2m_add_foreign(), is added
to map pages from foreign guest into current dom0 for domU creation.
Such pages are typed p2m_map_foreign. Another function
p2m_remove_foreign() is added to remove such pages. Note, in
the remove path, we must release the refcount that was taken during
the map phase. This is done in p2m_remove_page, which also addresses
releasing of refcnt when the domain is destroyed.
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
xen/arch/x86/mm.c | 23 +++++++---
xen/arch/x86/mm/p2m.c | 101 +++++++++++++++++++++++++++++++++++++++++++++
xen/common/memory.c | 12 +++++-
xen/include/asm-arm/p2m.h | 9 ++++-
xen/include/asm-x86/p2m.h | 7 +++
5 files changed, 143 insertions(+), 9 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index e3da479..6c2edc4 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2810,7 +2810,7 @@ static struct domain *get_pg_owner(domid_t domid)
goto out;
}
- if ( unlikely(paging_mode_translate(curr)) )
+ if ( !is_pvh_domain(curr) && unlikely(paging_mode_translate(curr)) )
{
MEM_LOG("Cannot mix foreign mappings with translated domains");
goto out;
@@ -4522,7 +4522,8 @@ static int handle_iomem_range(unsigned long s, unsigned
long e, void *p)
static int xenmem_add_to_physmap_once(
struct domain *d,
- const struct xen_add_to_physmap *xatp)
+ const struct xen_add_to_physmap *xatp,
+ struct domain *fdom)
{
struct page_info *page = NULL;
unsigned long gfn = 0; /* gcc ... */
@@ -4581,6 +4582,13 @@ static int xenmem_add_to_physmap_once(
page = mfn_to_page(mfn);
break;
}
+
+ case XENMAPSPACE_gmfn_foreign:
+ {
+ rc = p2m_add_foreign(d, xatp->idx, xatp->gpfn, fdom);
+ return rc;
+ }
+
default:
break;
}
@@ -4646,7 +4654,7 @@ static int xenmem_add_to_physmap(struct domain *d,
start_xatp = *xatp;
while ( xatp->size > 0 )
{
- rc = xenmem_add_to_physmap_once(d, xatp);
+ rc = xenmem_add_to_physmap_once(d, xatp, NULL);
if ( rc < 0 )
return rc;
@@ -4672,11 +4680,12 @@ static int xenmem_add_to_physmap(struct domain *d,
return rc;
}
- return xenmem_add_to_physmap_once(d, xatp);
+ return xenmem_add_to_physmap_once(d, xatp, NULL);
}
static int xenmem_add_to_physmap_range(struct domain *d,
- struct xen_add_to_physmap_range *xatpr)
+ struct xen_add_to_physmap_range *xatpr,
+ struct domain *fdom)
{
/* Process entries in reverse order to allow continuations */
while ( xatpr->size > 0 )
@@ -4693,7 +4702,7 @@ static int xenmem_add_to_physmap_range(struct domain *d,
xatp.space = xatpr->space;
xatp.idx = idx;
xatp.gpfn = gpfn;
- rc = xenmem_add_to_physmap_once(d, &xatp);
+ rc = xenmem_add_to_physmap_once(d, &xatp, fdom);
if ( copy_to_guest_offset(xatpr->errs, xatpr->size-1, &rc, 1) )
return -EFAULT;
@@ -4780,7 +4789,7 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void)
arg)
}
rc = xsm_add_to_physmap(XSM_TARGET, current->domain, d, fd);
if ( rc == 0 )
- rc = xenmem_add_to_physmap_range(d, &xatpr);
+ rc = xenmem_add_to_physmap_range(d, &xatpr, fd);
rcu_unlock_domain(d);
if ( fd )
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 0659ef1..fe8c2f6 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -527,6 +527,10 @@ p2m_remove_page(struct p2m_domain *p2m, unsigned long gfn,
unsigned long mfn,
mfn_return = p2m->get_entry(p2m, gfn + i, &t, &a, 0, NULL);
if ( !p2m_is_grant(t) && !p2m_is_shared(t) && !p2m_is_foreign(t) )
set_gpfn_from_mfn(mfn+i, INVALID_M2P_ENTRY);
+
+ /* foreign pages are always refcnt'd in the add path. */
+ if ( p2m_is_foreign(t) )
+ put_page(mfn_to_page(mfn_return));
ASSERT( !p2m_is_valid(t) || mfn + i == mfn_x(mfn_return) );
}
}
@@ -1741,6 +1745,103 @@ out_p2m_audit:
#endif /* P2M_AUDIT */
/*
+ * Add frames from foreign domain to target 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 p2m_remove_page
+ * via p2m_remove_foreign.
+ * Returns: 0 ==> success
+ */
+int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
+ unsigned long gpfn, struct domain *fdom)
+{
+ p2m_type_t p2mt, p2mt_prev;
+ mfn_t prev_mfn, mfn;
+ struct page_info *page;
+ int rc = 0;
+
+ if ( tdom == fdom || !tdom || !fdom || !is_pvh_domain(tdom) )
+ return -EINVAL;
+
+ /* 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);
+ return -EINVAL;
+ }
+ mfn = page_to_mfn(page);
+
+ /* Remove previously mapped page if it is present. */
+ prev_mfn = get_gfn(tdom, gpfn, &p2mt_prev);
+ if ( mfn_valid(prev_mfn) )
+ {
+ if ( is_xen_heap_mfn(mfn_x(prev_mfn)) )
+ /* Xen heap frames are simply unhooked from this phys slot */
+ guest_physmap_remove_page(tdom, gpfn, mfn_x(prev_mfn), 0);
+ else
+ /* Normal domain memory is freed, to avoid leaking memory. */
+ guest_remove_page(tdom, 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(tdom, gpfn, mfn) == 0 )
+ {
+ gdprintk(XENLOG_WARNING, "set_foreign_p2m_entry failed. "
+ "gpfn:%lx mfn:%lx fgfn:%lx td:%d fd:%d\n",
+ gpfn, mfn_x(mfn), fgfn, tdom->domain_id, fdom->domain_id);
+ 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(tdom, gpfn);
+
+ return rc;
+}
+
+/* Note, the refcnt taken in p2m_add_foreign is released in p2m_remove_page */
+int p2m_remove_foreign(struct domain *d, unsigned long gpfn)
+{
+ mfn_t mfn;
+ p2m_type_t p2mt;
+ struct domain *foreign_dom;
+
+ ASSERT(is_pvh_domain(d));
+
+ mfn = get_gfn_query(d, gpfn, &p2mt);
+ if ( unlikely(!p2m_is_foreign(p2mt)) )
+ {
+ put_gfn(d, gpfn);
+ gdprintk(XENLOG_WARNING, "Invalid type for gpfn:%lx domid:%d t:%d\n",
+ gpfn, d->domain_id, p2mt);
+ return -EINVAL;
+ }
+ if ( unlikely(!mfn_valid(mfn)) )
+ {
+ put_gfn(d, gpfn);
+ gdprintk(XENLOG_WARNING, "Invalid mfn for gpfn:%lx domid:%d\n",
+ gpfn, d->domain_id);
+ return -EINVAL;
+ }
+
+ foreign_dom = page_get_owner(mfn_to_page(mfn));
+ ASSERT(d != foreign_dom);
+
+ guest_physmap_remove_page(d, gpfn, mfn_x(mfn), 0);
+ put_gfn(d, gpfn);
+ return 0;
+}
+/*
* Local variables:
* mode: C
* c-file-style: "BSD"
diff --git a/xen/common/memory.c b/xen/common/memory.c
index eb7b72b..53f67c1 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -678,6 +678,7 @@ long do_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
struct xen_remove_from_physmap xrfp;
struct page_info *page;
struct domain *d;
+ p2m_type_t p2mt = INT_MAX;
if ( copy_from_guest(&xrfp, arg, 1) )
return -EFAULT;
@@ -693,12 +694,21 @@ long do_memory_op(unsigned long cmd,
XEN_GUEST_HANDLE_PARAM(void) arg)
return rc;
}
- page = get_page_from_gfn(d, xrfp.gpfn, NULL, P2M_ALLOC);
+ /*
+ * If autotranslate guest, (eg 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.
+ */
+ page = get_page_from_gfn(d, xrfp.gpfn, &p2mt, P2M_ALLOC);
if ( page )
{
guest_physmap_remove_page(d, xrfp.gpfn, page_to_mfn(page), 0);
put_page(page);
}
+ else if ( p2m_is_foreign(p2mt) )
+ rc = p2m_remove_foreign(d, xrfp.gpfn);
else
rc = -ENOENT;
diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
index c660820..485e907 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -83,7 +83,8 @@ static inline struct page_info *get_page_from_gfn(
struct page_info *page;
unsigned long mfn = gmfn_to_mfn(d, gfn);
- ASSERT(t == NULL);
+ if ( t )
+ ASSERT(*t == INT_MAX);
if (!mfn_valid(mfn))
return NULL;
@@ -110,6 +111,12 @@ static inline int get_page_and_type(struct page_info *page,
return rc;
}
+#define p2m_is_foreign(_t) (0 && (_t))
+static inline int p2m_remove_foreign(struct domain *d, unsigned long gpfn)
+{
+ return -ENOSYS;
+}
+
#endif /* _XEN_P2M_H */
/*
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 6fc71a1..6371705 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -515,6 +515,13 @@ int clear_mmio_p2m_entry(struct domain *d, unsigned long
gfn);
/* Set foreign mfn in the current guest's p2m table. */
int set_foreign_p2m_entry(struct domain *domp, unsigned long gfn, mfn_t mfn);
+/* Add foreign mapping to the guest's p2m table. */
+int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
+ unsigned long gpfn, struct domain *fdom);
+
+/* Remove foreign mapping from the guest's p2m table. */
+int p2m_remove_foreign(struct domain *d, unsigned long gpfn);
+
/*
* Populate-on-demand
*/
--
1.7.2.3
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