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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [V8 PATCH 5/8] pvh dom0: Add and remove foreign pages
In this patch, a new function, p2m_add_foreign(), is added
to map pages from foreign guest into dom0 for domU creation.
Such pages are typed p2m_map_foreign. 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 function
atomic_write_ept_entry for convenience. Finally, p2m_teardown adds a
call to allow for the cleanup of foreign pages during it's destruction.
Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
---
xen/arch/x86/mm.c | 5 +++
xen/arch/x86/mm/p2m-ept.c | 34 ++++++++++++++---
xen/arch/x86/mm/p2m-pt.c | 9 ++++-
xen/arch/x86/mm/p2m.c | 95 +++++++++++++++++++++++++++++++++++++++++++++--
xen/include/asm-x86/p2m.h | 3 ++
5 files changed, 135 insertions(+), 11 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index fdc5ed3..fcd3178 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4583,6 +4583,11 @@ int xenmem_add_to_physmap_one(
page = mfn_to_page(mfn);
break;
}
+ case XENMAPSPACE_gmfn_foreign:
+ {
+ rc = p2m_add_foreign(d, idx, gpfn, foreign_domid);
+ return rc;
+ }
default:
break;
}
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index 08d1d72..beb7288 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 +44,30 @@ static inline bool_t is_epte_valid(ept_entry_t *e)
return (e->epte != 0 && e->sa_p2mt != p2m_invalid);
}
+static inline void atomic_write_ept_entry(ept_entry_t *entryptr,
+ const ept_entry_t *new)
+{
+ unsigned long oldmfn = 0;
+
+ if ( p2m_is_foreign(new->sa_p2mt) )
+ {
+ struct page_info *page;
+ struct domain *fdom;
+
+ ASSERT(mfn_valid(new->mfn));
+ page = mfn_to_page(new->mfn);
+ fdom = page_get_owner(page);
+ get_page(page, fdom);
+ }
+ if ( p2m_is_foreign(entryptr->sa_p2mt) )
+ oldmfn = entryptr->mfn;
+
+ write_atomic(&entryptr->epte, new->epte);
+
+ if ( oldmfn )
+ put_page(mfn_to_page(oldmfn));
+}
+
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 +400,7 @@ 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);
+ atomic_write_ept_entry(ept_entry, &new_entry);
}
else
{
@@ -398,7 +420,7 @@ 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);
+ atomic_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 +450,7 @@ 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);
+ atomic_write_ept_entry(ept_entry, &new_entry);
}
/* Track the highest gfn for which we have ever had a valid mapping */
@@ -665,7 +687,7 @@ 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);
+ atomic_write_ept_entry(&epte[i], &e);
}
}
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index 09b60ce..766fd67 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -276,7 +276,7 @@ p2m_next_level(struct p2m_domain *p2m, mfn_t *table_mfn,
void **table,
return 1;
}
-// Returns 0 on error (out of memory)
+// Returns 0 on error (out of memory, or unimplemented p2m type)
static int
p2m_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma)
@@ -312,6 +312,13 @@ p2m_set_entry(struct p2m_domain *p2m, unsigned long gfn,
mfn_t mfn,
__trace_var(TRC_MEM_SET_P2M_ENTRY, 0, sizeof(t), &t);
}
+ if ( p2m_is_foreign(p2mt) )
+ {
+ /* pvh fixme: foreign types are only supported on ept at present */
+ gdprintk(XENLOG_WARNING, "Unimplemented foreign p2m type.\n");
+ return 0;
+ }
+
if ( !p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder, gfn,
L4_PAGETABLE_SHIFT - PAGE_SHIFT,
L4_PAGETABLE_ENTRIES, PGT_l3_page_table) )
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 7050f6a..52dd1e4 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -36,6 +36,7 @@
#include <xen/event.h>
#include <asm/hvm/nestedhvm.h>
#include <asm/hvm/svm/amd-iommu-proto.h>
+#include <xsm/xsm.h>
#include "mm-locks.h"
@@ -275,14 +276,19 @@ struct page_info *get_page_from_gfn_p2m(
/* Fast path: look up and get out */
p2m_read_lock(p2m);
mfn = __get_gfn_type_access(p2m, gfn, t, a, 0, NULL, 0);
- if ( (p2m_is_ram(*t) || p2m_is_grant(*t))
+ if ( (p2m_is_ram(*t) || p2m_is_grant(*t) || p2m_is_foreign(*t) )
&& mfn_valid(mfn)
&& !((q & P2M_UNSHARE) && p2m_is_shared(*t)) )
{
page = mfn_to_page(mfn);
- if ( !get_page(page, d)
- /* Page could be shared */
- && !get_page(page, dom_cow) )
+ if ( p2m_is_foreign(*t) )
+ {
+ struct domain *fdom = page_get_owner_and_reference(page);
+ ASSERT(fdom && fdom != d);
+ }
+ else if ( !get_page(page, d)
+ /* Page could be shared */
+ && !get_page(page, dom_cow) )
page = NULL;
}
p2m_read_unlock(p2m);
@@ -447,6 +453,10 @@ void p2m_teardown(struct p2m_domain *p2m)
d = p2m->domain;
p2m_lock(p2m);
+ /* pvh: we must release refcnt on all foreign pages */
+ if ( is_pvh_domain(d) )
+ p2m_change_entry_type_global(d, p2m_map_foreign, p2m_invalid);
+
ASSERT(atomic_read(&d->shr_pages) == 0);
p2m->phys_table = pagetable_null();
@@ -1710,6 +1720,83 @@ 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 XENMEM_remove_from_physmap path.
+ * Returns: 0 ==> success
+ */
+int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
+ unsigned long gpfn, domid_t fdid)
+{
+ int rc = -ESRCH;
+ p2m_type_t p2mt, p2mt_prev;
+ unsigned long prev_mfn, mfn;
+ struct page_info *page = NULL;
+ struct domain *fdom = NULL;
+
+ /* xentrace mapping pages from xen heap are owned by DOMID_XEN */
+ if ( (fdid == DOMID_XEN && (fdom = rcu_lock_domain(dom_xen)) == NULL) ||
+ (fdid != DOMID_XEN && (fdom = rcu_lock_domain_by_id(fdid)) == NULL) )
+ goto out;
+
+ if ( (rc = xsm_map_gmfn_foreign(XSM_TARGET, tdom, fdom)) )
+ goto out;
+
+ rc = -EINVAL;
+ if ( tdom == fdom || !tdom || !fdom || !is_pvh_domain(tdom) )
+ goto out;
+
+ /* 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);
+ goto out;
+ }
+ mfn = mfn_x(page_to_mfn(page));
+
+ /* Remove previously mapped page if it is present. */
+ prev_mfn = mfn_x(get_gfn(tdom, gpfn, &p2mt_prev));
+ if ( mfn_valid(_mfn(prev_mfn)) )
+ {
+ if ( is_xen_heap_mfn(prev_mfn) )
+ /* Xen heap frames are simply unhooked from this phys slot */
+ guest_physmap_remove_page(tdom, gpfn, 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(mfn)) == 0 )
+ gdprintk(XENLOG_WARNING, "set_foreign_p2m_entry failed. "
+ "gpfn:%lx mfn:%lx fgfn:%lx td:%d fd:%d\n",
+ gpfn, mfn, fgfn, tdom->domain_id, fdom->domain_id);
+ else
+ rc = 0;
+
+ 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);
+
+out:
+ if ( fdom )
+ rcu_unlock_domain(fdom);
+ return rc;
+}
+/*
* Local variables:
* mode: C
* c-file-style: "BSD"
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index ad2383e..9e691f2 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -512,6 +512,9 @@ p2m_type_t p2m_change_type(struct domain *d, unsigned long
gfn,
int set_mmio_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn);
int clear_mmio_p2m_entry(struct domain *d, unsigned long gfn);
+/* Add foreign mapping to the guest's p2m table. */
+int p2m_add_foreign(struct domain *tdom, unsigned long fgfn,
+ unsigned long gpfn, domid_t foreign_domid);
/*
* Populate-on-demand
--
1.8.3.1
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