(CC Stefano's new e-mail address)
Hello Benjamin,
On 04/04/16 19:48, Benjamin Sanda wrote:
xen/arch/arm/mm.c | 3 ++-
xen/arch/arm/p2m.c | 35 +++++++++++++++++++++++++++++++----
2 files changed, 33 insertions(+), 5 deletions(-)
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 81f9e2e..19d6c2c 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1099,7 +1099,8 @@ int xenmem_add_to_physmap_one(
{
struct domain *od;
p2m_type_t p2mt;
- od = rcu_lock_domain_by_any_id(foreign_domid);
+ od = get_pg_owner(foreign_domid);
+
Please also replace the call to rcu_unlock_domain by put_pg_owner to
stay consistent.
if ( od == NULL )
return -ESRCH;
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index a2a9c4b..a99b670 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -227,11 +227,38 @@ paddr_t p2m_lookup(struct domain *d, paddr_t paddr,
p2m_type_t *t)
{
paddr_t ret;
struct p2m_domain *p2m = &d->arch.p2m;
+ struct page_info *page;
+ unsigned long mfn;
- spin_lock(&p2m->lock);
- ret = __p2m_lookup(d, paddr, t);
- spin_unlock(&p2m->lock);
-
+ /*
+ * DOMID_XEN is considered a PV guest on x86 (i.e MFN == GFN), but
+ * on ARM there is no such concept. Thus requests to DOMID_XEN
+ * on ARM use a MFN address directly and do not need translation
+ * from PFN.
+ */
The coding style for the comment should be:
/*
* FOo
* Bar
*/
+ if(DOMID_XEN != d->domain_id)
if ( ... )
+ {
+ spin_lock(&p2m->lock);
+ ret = __p2m_lookup(d, paddr, t);
+ spin_unlock(&p2m->lock);
+ }
+ else
+ {
+ /* retrieve the page to determine read/write or read only mapping */
+ mfn = paddr >> PAGE_SHIFT;
+ if (mfn_valid(mfn))
+ {
+ page = mfn_to_page(mfn);
+ *t = (page->u.inuse.type_info == PGT_writable_page ?
+ p2m_ram_rw : p2m_ram_ro);
Unfortunately, xenmem_add_to_physmap_one will ignore the return type and
will always map using the type p2m_map_foreign. I would introduce
a new type p2m_map_foreign_ro to allow read-only foreign mapping.
I've looked at the x86 code (p2m_add_foreign) and I haven't been able to
find how the page will be mapped read-only in the guest P2M.
get_page_from_gfn will always return p2m_raw_rw for DOMID_XEN as it's a
non translated domain.
Andrew and Jan, do you know how this is supposed to work when xentrace
is used in a HVM domain? Does x86 Xen always mapped Read-Write the page?
+ }
+ else
+ {
+ *t = p2m_invalid;
+ }
The brackets are not necessary for a single statement.
+ ret = paddr;
+ }
+
return ret;
}
Regards,
--
Julien Grall
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