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[PATCH v2 12/13] x86/shadow: "monitor table" is a HVM-only concept


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 30 Mar 2023 13:31:41 +0200
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  • Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>
  • Delivery-date: Thu, 30 Mar 2023 11:31:48 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

It looks like in the combination of aff8bf94ce65 ('x86/shadow: only
4-level guest code needs building when !HVM') and 0b841314dace
('x86/shadow: sh_{make,destroy}_monitor_table() are "even more" HVM-
only') I didn't go quite far enough: SH_type_monitor_table is also
effectively unused when !HVM.

The assertion early in sh_destroy_shadow() can have the type dropped
altogether: it shouldn't make it here in the first place. Pages of
this type are freed directly from sh_destroy_monitor_table() only.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1190,7 +1190,6 @@ void sh_destroy_shadow(struct domain *d,
     ASSERT(t == SH_type_fl1_32_shadow  ||
            t == SH_type_fl1_pae_shadow ||
            t == SH_type_fl1_64_shadow  ||
-           t == SH_type_monitor_table  ||
            (is_pv_32bit_domain(d) && t == SH_type_l4_64_shadow) ||
            (page_get_owner(mfn_to_page(backpointer(sp))) == d));
 
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -205,8 +205,7 @@ extern void shadow_audit_tables(struct v
 #define SH_type_l4_64_shadow   6U /* shadowing a 64-bit L4 page */
 #define SH_type_max_shadow     6U
 #define SH_type_p2m_table      7U /* in use as the p2m table */
-#define SH_type_monitor_table  8U /* in use as a monitor table */
-#define SH_type_unused         9U
+#define SH_type_unused         8U
 #endif
 
 #ifndef CONFIG_PV32 /* Unused (but uglier to #ifdef above): */




 


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