From 63137a87311e1081bce0c5a4364492b4fc728bfb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.com>
Date: Tue, 9 Dec 2025 11:27:39 +0100
Subject: [PATCH] xen/domain: introduce generic functions for domain struct
 allocation and freeing
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Move x86's free_domain_struct() to common code since it is shared between
architectures.

Move the x86 version of alloc_domain_struct() to common code as most of the
logic is architecture-independent. To handle the remaining architectural
differences, introduce arch_domain_struct_memflags() for x86-specific
allocation requirements.

No functional change.

Suggested-by: Jan Beulich <jbeulich@suse.com>
[Introduce an arch-specific function instead of using a weak function]
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Michal Orzel <michal.orzel@amd.com>
---
 xen/arch/arm/domain.c             | 17 -----------------
 xen/arch/ppc/stubs.c              | 10 ----------
 xen/arch/riscv/stubs.c            | 10 ----------
 xen/arch/x86/domain.c             | 15 ++-------------
 xen/arch/x86/include/asm/domain.h |  3 +++
 xen/common/domain.c               | 21 +++++++++++++++++++++
 6 files changed, 26 insertions(+), 50 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 3e32a15cac..47973f99d9 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -468,23 +468,6 @@ void startup_cpu_idle_loop(void)
     reset_stack_and_jump(idle_loop);
 }
 
-struct domain *alloc_domain_struct(void)
-{
-    struct domain *d;
-    BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
-    d = alloc_xenheap_pages(0, 0);
-    if ( d == NULL )
-        return NULL;
-
-    clear_page(d);
-    return d;
-}
-
-void free_domain_struct(struct domain *d)
-{
-    free_xenheap_page(d);
-}
-
 void dump_pageframe_info(struct domain *d)
 {
 
diff --git a/xen/arch/ppc/stubs.c b/xen/arch/ppc/stubs.c
index 75ebcae5e2..9953ea1c6c 100644
--- a/xen/arch/ppc/stubs.c
+++ b/xen/arch/ppc/stubs.c
@@ -147,11 +147,6 @@ void startup_cpu_idle_loop(void)
     BUG_ON("unimplemented");
 }
 
-void free_domain_struct(struct domain *d)
-{
-    BUG_ON("unimplemented");
-}
-
 void dump_pageframe_info(struct domain *d)
 {
     BUG_ON("unimplemented");
@@ -269,11 +264,6 @@ void vcpu_kick(struct vcpu *v)
     BUG_ON("unimplemented");
 }
 
-struct domain *alloc_domain_struct(void)
-{
-    BUG_ON("unimplemented");
-}
-
 struct vcpu *alloc_vcpu_struct(const struct domain *d)
 {
     BUG_ON("unimplemented");
diff --git a/xen/arch/riscv/stubs.c b/xen/arch/riscv/stubs.c
index 340ed3cd6c..fe7d85ee1d 100644
--- a/xen/arch/riscv/stubs.c
+++ b/xen/arch/riscv/stubs.c
@@ -121,11 +121,6 @@ void startup_cpu_idle_loop(void)
     BUG_ON("unimplemented");
 }
 
-void free_domain_struct(struct domain *d)
-{
-    BUG_ON("unimplemented");
-}
-
 void dump_pageframe_info(struct domain *d)
 {
     BUG_ON("unimplemented");
@@ -243,11 +238,6 @@ void vcpu_kick(struct vcpu *v)
     BUG_ON("unimplemented");
 }
 
-struct domain *alloc_domain_struct(void)
-{
-    BUG_ON("unimplemented");
-}
-
 struct vcpu *alloc_vcpu_struct(const struct domain *d)
 {
     BUG_ON("unimplemented");
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index d89b7667d4..bd75d044a0 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -463,10 +463,8 @@ void domain_cpu_policy_changed(struct domain *d)
     }
 }
 
-struct domain *alloc_domain_struct(void)
+unsigned int arch_domain_struct_memflags(void)
 {
-    struct domain *d;
-
     /*
      * Without CONFIG_BIGMEM, we pack the PDX of the domain structure into
      * a 32-bit field within the page_info structure. Hence the MEMF_bits()
@@ -492,16 +490,7 @@ struct domain *alloc_domain_struct(void)
                 - 1;
 #endif
 
-    BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
-    d = alloc_xenheap_pages(0, MEMF_bits(bits));
-    if ( d != NULL )
-        clear_page(d);
-    return d;
-}
-
-void free_domain_struct(struct domain *d)
-{
-    free_xenheap_page(d);
+    return MEMF_bits(bits);
 }
 
 struct vcpu *alloc_vcpu_struct(const struct domain *d)
diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
index 5df8c78253..386ec61745 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -12,6 +12,9 @@
 #include <public/vcpu.h>
 #include <public/hvm/hvm_info_table.h>
 
+unsigned int arch_domain_struct_memflags(void);
+#define arch_domain_struct_memflags arch_domain_struct_memflags
+
 #define has_32bit_shinfo(d)    ((d)->arch.has_32bit_shinfo)
 
 /*
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 850daf1ee8..93c71bc766 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -799,6 +799,27 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
     return arch_sanitise_domain_config(config);
 }
 
+struct domain *alloc_domain_struct(void)
+{
+#ifndef arch_domain_struct_memflags
+# define arch_domain_struct_memflags() 0
+#endif
+
+    struct domain *d = alloc_xenheap_pages(0, arch_domain_struct_memflags());
+
+    BUILD_BUG_ON(sizeof(*d) > PAGE_SIZE);
+
+    if ( d )
+        clear_page(d);
+
+    return d;
+}
+
+void free_domain_struct(struct domain *d)
+{
+    free_xenheap_page(d);
+}
+
 struct domain *domain_create(domid_t domid,
                              struct xen_domctl_createdomain *config,
                              unsigned int flags)