Hi Jan,
On 04/06/2019 13:44, Jan Beulich wrote:
A couple of adjustments are needed to code checking for dom_cow, but
since there are pretty few it is probably better to adjust those than
to set up and keep around a never used domain.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
Acked-by: Julien Grall <julien.gr...@arm.com>
Cheers,
---
v2: Use #if/#else. Split out emul-priv-op.c change.
---
While for now this avoids creating the domain on Arm only, Tamas'es
patch switching to CONFIG_MEM_SHARING will make x86 leverage this too.
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -967,8 +967,8 @@ get_page_from_l1e(
return flip;
}
- if ( unlikely( (real_pg_owner != pg_owner) &&
- (real_pg_owner != dom_cow) ) )
+ if ( unlikely((real_pg_owner != pg_owner) &&
+ (!dom_cow || (real_pg_owner != dom_cow))) )
{
/*
* Let privileged domains transfer the right to map their target
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -568,7 +568,8 @@ struct page_info *p2m_get_page_from_gfn(
}
else if ( !get_page(page, p2m->domain) &&
/* Page could be shared */
- (!p2m_is_shared(*t) || !get_page(page, dom_cow)) )
+ (!dom_cow || !p2m_is_shared(*t) ||
+ !get_page(page, dom_cow)) )
page = NULL;
}
p2m_read_unlock(p2m);
@@ -941,7 +942,8 @@ guest_physmap_add_entry(struct domain *d
/* Then, look for m->p mappings for this range and deal with them */
for ( i = 0; i < (1UL << page_order); i++ )
{
- if ( page_get_owner(mfn_to_page(mfn_add(mfn, i))) == dom_cow )
+ if ( dom_cow &&
+ page_get_owner(mfn_to_page(mfn_add(mfn, i))) == dom_cow )
{
/* This is no way to add a shared page to your physmap! */
gdprintk(XENLOG_ERR, "Adding shared mfn %lx directly to dom%d physmap
not allowed.\n",
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -74,7 +74,9 @@ integer_param("hardware_dom", hardware_d
/* Private domain structs for DOMID_XEN, DOMID_IO, etc. */
struct domain *__read_mostly dom_xen;
struct domain *__read_mostly dom_io;
+#ifdef CONFIG_HAS_MEM_SHARING
struct domain *__read_mostly dom_cow;
+#endif
struct vcpu *idle_vcpu[NR_CPUS] __read_mostly;
@@ -547,6 +549,7 @@ void __init setup_special_domains(void)
if ( IS_ERR(dom_io) )
panic("Failed to create d[IO]: %ld\n", PTR_ERR(dom_io));
+#ifdef CONFIG_HAS_MEM_SHARING
/*
* Initialise our COW domain.
* This domain owns sharable pages.
@@ -554,6 +557,7 @@ void __init setup_special_domains(void)
dom_cow = domain_create(DOMID_COW, NULL, false);
if ( IS_ERR(dom_cow) )
panic("Failed to create d[COW]: %ld\n", PTR_ERR(dom_cow));
+#endif
}
void domain_update_node_affinity(struct domain *d)
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -1095,7 +1095,7 @@ map_grant_ref(
host_map_created = true;
}
}
- else if ( owner == rd || owner == dom_cow )
+ else if ( owner == rd || (dom_cow && owner == dom_cow) )
{
if ( (op->flags & GNTMAP_device_map) && !(op->flags &
GNTMAP_readonly) )
{
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -643,7 +643,12 @@ static inline void filtered_flush_tlb_ma
}
/* Private domain structs for DOMID_XEN, DOMID_IO, etc. */
-extern struct domain *dom_xen, *dom_io, *dom_cow;
+extern struct domain *dom_xen, *dom_io;
+#ifdef CONFIG_HAS_MEM_SHARING
+extern struct domain *dom_cow;
+#else
+# define dom_cow NULL
+#endif
enum XENSHARE_flags {
SHARE_rw,
--
Julien Grall
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