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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 18:46:06 -0800
Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> On Wed, 11 Dec 2013 15:29:03 +0100
> Tim Deegan <tim@xxxxxxx> wrote:
..........
> I'll have another version out hopefully tomorrow, with
> get_page* and put_page* in ept path, and p2m_teardown fixed up, and
> all tested. I'm thinking something along the lines of:
>
> ept_set_entry():
> ...
> if (p2mt == foreign)
> {
> page = mfn_to_page(mfn);
> fdom = page_get_owner(page);
> get_page(page, fdom);
> }
> table = map_domain_page(pagetable_get_pfn(p2m_get_pagetable(p2m)));
> .....
>
>
> thanks a lot,
> Mukesh
Ok, this is what I came up with, please lmk. Thanks.
CCing Jun and Eddie for EPT changes.
-Mukesh
------------
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, it is the
nature of such pages that a refcnt is held during their stay in the p2m.
The refcnt is added and released in the low level ept code for convenience.
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
xen/arch/x86/mm.c | 23 +++++++---
xen/arch/x86/mm/p2m-ept.c | 30 +++++++++++---
xen/arch/x86/mm/p2m.c | 98 +++++++++++++++++++++++++++++++++++++++++++++
xen/common/memory.c | 12 +++++-
xen/include/asm-arm/p2m.h | 8 +++-
xen/include/asm-x86/p2m.h | 7 +++
6 files changed, 163 insertions(+), 15 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-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 08d1d72..3b9f764 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -36,8 +36,6 @@
#define atomic_read_ept_entry(__pepte) \
( (ept_entry_t) { .epte = read_atomic(&(__pepte)->epte) } )
-#define atomic_write_ept_entry(__pepte, __epte) \
- write_atomic(&(__pepte)->epte, (__epte).epte)
#define is_epte_present(ept_entry) ((ept_entry)->epte & 0x7)
#define is_epte_superpage(ept_entry) ((ept_entry)->sp)
@@ -46,6 +44,26 @@ static inline bool_t is_epte_valid(ept_entry_t *e)
return (e->epte != 0 && e->sa_p2mt != p2m_invalid);
}
+static inline void write_ept_entry(ept_entry_t *entryptr, ept_entry_t *new)
+{
+ if ( p2m_is_foreign(entryptr->sa_p2mt) )
+ put_page(mfn_to_page(entryptr->mfn));
+
+ if ( p2m_is_foreign(new->sa_p2mt) )
+ {
+ struct page_info *page;
+ struct domain *fdom;
+
+ ASSERT(mfn_valid(new->mfn));
+ ASSERT(new->mfn != entryptr->mfn);
+ page = mfn_to_page(new->mfn);
+ fdom = page_get_owner(page);
+ get_page(page, fdom);
+ }
+ write_atomic(&entryptr->epte, new->epte);
+}
+
+
static void ept_p2m_type_to_flags(ept_entry_t *entry, p2m_type_t type,
p2m_access_t access)
{
/* First apply type permissions */
@@ -378,7 +396,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn,
mfn_t mfn,
ept_p2m_type_to_flags(&new_entry, p2mt, p2ma);
}
- atomic_write_ept_entry(ept_entry, new_entry);
+ write_ept_entry(ept_entry, &new_entry);
}
else
{
@@ -398,7 +416,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn,
mfn_t mfn,
/* now install the newly split ept sub-tree */
/* NB: please make sure domian is paused and no in-fly VT-d DMA. */
- atomic_write_ept_entry(ept_entry, split_ept_entry);
+ write_ept_entry(ept_entry, &split_ept_entry);
/* then move to the level we want to make real changes */
for ( ; i > target; i-- )
@@ -428,7 +446,7 @@ ept_set_entry(struct p2m_domain *p2m, unsigned long gfn,
mfn_t mfn,
ept_p2m_type_to_flags(&new_entry, p2mt, p2ma);
- atomic_write_ept_entry(ept_entry, new_entry);
+ write_ept_entry(ept_entry, &new_entry);
}
/* Track the highest gfn for which we have ever had a valid mapping */
@@ -665,7 +683,7 @@ static void ept_change_entry_type_page(mfn_t ept_page_mfn,
int ept_page_level,
e.sa_p2mt = nt;
ept_p2m_type_to_flags(&e, nt, e.access);
- atomic_write_ept_entry(&epte[i], e);
+ write_ept_entry(&epte[i], &e);
}
}
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 0659ef1..29f7b23 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -479,6 +479,8 @@ void p2m_teardown(struct p2m_domain *p2m)
/* Does not fail with ENOMEM given the DESTROY flag */
BUG_ON(mem_sharing_unshare_page(d, gfn, MEM_SHARING_DESTROY_GFN));
}
+ if ( p2m_is_foreign(t) )
+ put_page(mfn_to_page(mfn));
}
p2m->phys_table = pagetable_null();
@@ -1741,6 +1743,102 @@ 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 in lower level routines
+ * so it is not lost while mapped here. The refcnt is released
+ * via the p2m_remove_foreign path.
+ * 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);
+ rc = -EINVAL;
+ }
+ put_page(page);
+
+ /*
+ * 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;
+}
+
+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..a664950 100644
--- a/xen/include/asm-arm/p2m.h
+++ b/xen/include/asm-arm/p2m.h
@@ -83,7 +83,7 @@ static inline struct page_info *get_page_from_gfn(
struct page_info *page;
unsigned long mfn = gmfn_to_mfn(d, gfn);
- ASSERT(t == NULL);
+ ASSERT(!t || *t == INT_MAX);
if (!mfn_valid(mfn))
return NULL;
@@ -110,6 +110,12 @@ 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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