[PATCH v2] x86/mapcache: Initialise the mapcache for the idle domain

[Elias El Yandouzi <eliasely@amazon.com>]

From: Hongyan Xia <hongyxia@amazon.com>

In order to use the mapcache in the idle domain, we also have to
populate its page tables in the PERDOMAIN region, and we need to move
mapcache_domain_init() earlier in arch_domain_create().

Note, commit 'x86: lift mapcache variable to the arch level' has
initialised the mapcache for HVM domains. With this patch, PV, HVM,
idle domains now all initialise the mapcache.

Signed-off-by: Wei Wang <wawei@amazon.de>
Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Elias El Yandouzi <eliasely@amazon.com>

----

	Changes in V2:
          * Free resources if mapcache initialisation fails
          * Remove `is_idle_domain()` check from `create_perdomain_mappings()`

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 8ef3f7746f..d4c125bc14 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -750,9 +750,16 @@ int arch_domain_create(struct domain *d,
 
     spin_lock_init(&d->arch.e820_lock);
 
+    if ( (rc = mapcache_domain_init(d)) != 0)
+    {
+        free_perdomain_mappings(d);
+        return rc;
+    }
+
     /* Minimal initialisation for the idle domain. */
     if ( unlikely(is_idle_domain(d)) )
     {
+        struct page_info *pg = d->arch.perdomain_l3_pg;
         static const struct arch_csw idle_csw = {
             .from = paravirt_ctxt_switch_from,
             .to   = paravirt_ctxt_switch_to,
@@ -763,6 +770,9 @@ int arch_domain_create(struct domain *d,
 
         d->arch.cpu_policy = ZERO_BLOCK_PTR; /* Catch stray misuses. */
 
+        idle_pg_table[l4_table_offset(PERDOMAIN_VIRT_START)] =
+            l4e_from_page(pg, __PAGE_HYPERVISOR_RW);
+
         return 0;
     }
 
@@ -843,8 +853,6 @@ int arch_domain_create(struct domain *d,
 
     psr_domain_init(d);
 
-    mapcache_domain_init(d);
-
     if ( is_hvm_domain(d) )
     {
         if ( (rc = hvm_domain_initialise(d, config)) != 0 )
-- 
2.40.1