[PATCH v2] xen/domain: introduce generic functions for domain struct allocation and freeing

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

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_alloc_domain_struct_bits() for x86-specific
allocation requirements.

No functional change.

Suggested-By: Jan Beulich <jbeulich@xxxxxxxx>
[Introduce an arch-specific function instead of using a weak function]
Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
- CI test results: 
https://gitlab.com/xen-project/people/olkur/xen/-/pipelines/2180836457
- Introduce an arch-specific function to handle differences between arch-es
  in domain structure allocation requirements, instead of relying on a weak
  function.
- Add Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>.
- Move free_domain_struct() to common code.
- Update the commit message.
---
 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/pv/domain.h |  3 +++
 xen/common/domain.c                  | 23 +++++++++++++++++++++++
 6 files changed, 28 insertions(+), 50 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index ab78444335..3e3a1fb9f5 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -480,23 +480,6 @@ 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 3a21e035f4..34a02f089e 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_alloc_domain_struct_bits(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 bits;
 }
 
 struct vcpu *alloc_vcpu_struct(const struct domain *d)
diff --git a/xen/arch/x86/include/asm/pv/domain.h 
b/xen/arch/x86/include/asm/pv/domain.h
index 582d004051..6e65bc22fc 100644
--- a/xen/arch/x86/include/asm/pv/domain.h
+++ b/xen/arch/x86/include/asm/pv/domain.h
@@ -18,6 +18,9 @@ extern int8_t opt_pv32;
 # define opt_pv32 false
 #endif
 
+unsigned int arch_alloc_domain_struct_bits(void);
+#define arch_alloc_domin_struct_bits arch_alloc_domain_struct_bits
+
 /*
  * PCID values for the address spaces of 64-bit pv domains:
  *
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 3b6e9471c4..b51ce375df 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -799,6 +799,29 @@ static int sanitise_domain_config(struct 
xen_domctl_createdomain *config)
     return arch_sanitise_domain_config(config);
 }
 
+struct domain *alloc_domain_struct(void)
+{
+    struct domain *d;
+    unsigned int bits = 0;
+
+#ifdef arch_alloc_domin_struct_bits
+    bits = arch_alloc_domin_struct_bits();
+#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);
+}
+
 struct domain *domain_create(domid_t domid,
                              struct xen_domctl_createdomain *config,
                              unsigned int flags)
-- 
2.52.0