[PATCH 2/4] x86/domain: Implement arch_init_idle_domain()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The idle domain needs d->arch.ctxt_switch initialised on x86.  Implement the
new arch_init_idle_domain() in order to do this.

Right now this double-initalises the ctxt_switch pointer, but it's safe and
will stop happening when domain_create() is cleaned up as a consequence.

No practical change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
CC: Michal Orzel <michal.orzel@xxxxxxx>
CC: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/x86/domain.c             | 19 ++++++++++++-------
 xen/arch/x86/include/asm/domain.h |  3 +++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index ccadfe0c9e70..eff905c6c6e5 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -768,6 +768,17 @@ static bool emulation_flags_ok(const struct domain *d, 
uint32_t emflags)
     return true;
 }
 
+void __init arch_init_idle_domain(struct domain *d)
+{
+    static const struct arch_csw idle_csw = {
+        .from = paravirt_ctxt_switch_from,
+        .to   = paravirt_ctxt_switch_to,
+        .tail = idle_loop,
+    };
+
+    d->arch.ctxt_switch = &idle_csw;
+}
+
 int arch_domain_create(struct domain *d,
                        struct xen_domctl_createdomain *config,
                        unsigned int flags)
@@ -783,13 +794,7 @@ int arch_domain_create(struct domain *d,
     /* Minimal initialisation for the idle domain. */
     if ( unlikely(is_idle_domain(d)) )
     {
-        static const struct arch_csw idle_csw = {
-            .from = paravirt_ctxt_switch_from,
-            .to   = paravirt_ctxt_switch_to,
-            .tail = idle_loop,
-        };
-
-        d->arch.ctxt_switch = &idle_csw;
+        arch_init_idle_domain(d);
 
         d->arch.cpu_policy = ZERO_BLOCK_PTR; /* Catch stray misuses. */
 
diff --git a/xen/arch/x86/include/asm/domain.h 
b/xen/arch/x86/include/asm/domain.h
index f5daeb182baa..bca3258d69ac 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -779,6 +779,9 @@ struct arch_vcpu_io {
 /* Maxphysaddr supportable by the paging infrastructure. */
 unsigned int domain_max_paddr_bits(const struct domain *d);
 
+#define arch_init_idle_domain arch_init_idle_domain
+void arch_init_idle_domain(struct domain *d);
+
 #endif /* __ASM_DOMAIN_H__ */
 
 /*
-- 
2.39.2