[xen master] xen: introduce domain-layout.h with common domain_use_host_layout()

[patchbot@xxxxxxx]

commit b71811efe6e09ddb0fc3719ba47330a5c24a2e90
Author:     Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
AuthorDate: Thu May 7 10:58:43 2026 +0200
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Thu May 14 08:24:15 2026 +0200

    xen: introduce domain-layout.h with common domain_use_host_layout()
    
    domain_use_host_layout() is not architecture-specific and may be needed
    on x86 [1]. Replace the ARM-specific macro in asm/domain.h with a common
    static inline in a new dedicated header, xen/domain-layout.h.
    
    xen/domain.h would be the natural home, but placing it there would
    require including xen/paging.h (for paging_mode_translate()) and
    xen/sched.h (for is_hardware_domain()), which would introduce circular
    dependencies. A separate header that callers opt into avoids this.
    
    Adjust the implementation to take paging_mode_translate() into account
    so it works correctly for all architectures, including x86. Some extra
    details about implementation [2] and [3].
    
    To avoid the following compilation issue:
    
    In file included from ./include/xen/paging.h:4,
                     from ./include/xen/domain-layout.h:6,
                     from common/device-tree/domain-build.c:4:
    ./arch/riscv/include/asm/paging.h:17:48: error: 'struct page_info'
    declared inside parameter list will not be visible outside of this
    definition or declaration [-Werror]
       17 | void paging_free_page(struct domain *d, struct page_info *pg);
    
    add the forward declaration of struct page_info to RISC-V's asm/paging.h.
    
    [1] 
https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2602161038120.359097@ubuntu-linux-20-04-desktop/
    [2] 
https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2602271742400.3148344@ubuntu-linux-20-04-desktop/
    [3] 
https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2602271750190.3148344@ubuntu-linux-20-04-desktop/
    
    Suggested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
    Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
    Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 xen/arch/arm/domain_build.c           |  1 +
 xen/arch/arm/include/asm/domain.h     | 14 --------------
 xen/arch/arm/vgic-v3.c                |  1 +
 xen/arch/riscv/include/asm/paging.h   |  1 +
 xen/common/device-tree/domain-build.c |  1 +
 xen/include/xen/domain-layout.h       | 28 ++++++++++++++++++++++++++++
 6 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index ad665cd3c0..1efddc60ef 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -2,6 +2,7 @@
 #include <xen/init.h>
 #include <xen/bootinfo.h>
 #include <xen/compile.h>
+#include <xen/domain-layout.h>
 #include <xen/dom0less-build.h>
 #include <xen/fdt-domain-build.h>
 #include <xen/fdt-kernel.h>
diff --git a/xen/arch/arm/include/asm/domain.h 
b/xen/arch/arm/include/asm/domain.h
index b24f02d269..46a5cdc0c8 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -18,20 +18,6 @@ struct hvm_domain
     uint64_t              params[HVM_NR_PARAMS];
 };
 
-/*
- * Is the domain using the host memory layout?
- *
- * Direct-mapped domain will always have the RAM mapped with GFN == MFN.
- * To avoid any trouble finding space, it is easier to force using the
- * host memory layout.
- *
- * The hardware domain will use the host layout regardless of
- * direct-mapped because some OS may rely on a specific address ranges
- * for the devices.
- */
-#define domain_use_host_layout(d) (is_domain_direct_mapped(d) || \
-                                   is_hardware_domain(d))
-
 struct vtimer {
     struct vcpu *v;
     int irq;
diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
index 77aab5c3c2..77517c3030 100644
--- a/xen/arch/arm/vgic-v3.c
+++ b/xen/arch/arm/vgic-v3.c
@@ -10,6 +10,7 @@
  */
 
 #include <xen/bitops.h>
+#include <xen/domain-layout.h>
 #include <xen/init.h>
 #include <xen/irq.h>
 #include <xen/lib.h>
diff --git a/xen/arch/riscv/include/asm/paging.h 
b/xen/arch/riscv/include/asm/paging.h
index c1d225d02b..e487c89a4c 100644
--- a/xen/arch/riscv/include/asm/paging.h
+++ b/xen/arch/riscv/include/asm/paging.h
@@ -4,6 +4,7 @@
 #include <asm-generic/paging.h>
 
 struct domain;
+struct page_info;
 
 int paging_domain_init(struct domain *d);
 
diff --git a/xen/common/device-tree/domain-build.c 
b/xen/common/device-tree/domain-build.c
index c51520ebad..6949203dac 100644
--- a/xen/common/device-tree/domain-build.c
+++ b/xen/common/device-tree/domain-build.c
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
 #include <xen/bootinfo.h>
+#include <xen/domain-layout.h>
 #include <xen/fdt-domain-build.h>
 #include <xen/init.h>
 #include <xen/lib.h>
diff --git a/xen/include/xen/domain-layout.h b/xen/include/xen/domain-layout.h
new file mode 100644
index 0000000000..cc5e56c9da
--- /dev/null
+++ b/xen/include/xen/domain-layout.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef XEN_DOMAIN_LAYOUT_H
+#define XEN_DOMAIN_LAYOUT_H
+
+#include <xen/paging.h>
+#include <xen/sched.h>
+
+/*
+ * Is a domain using the host memory layout?
+ *
+ * domain_use_host_layout() is always False for PV domains (including Dom0).
+ *
+ * Direct-mapped domains (autotranslated domains with memory allocated
+ * contiguously and mapped 1:1 so that GFN == MFN) must use the host
+ * memory layout since GFN == MFN by definition.
+ *
+ * The hardware domain will use the host layout (regardless of
+ * direct-mapped) because some OS may rely on specific address ranges
+ * for the devices.
+ */
+static inline bool domain_use_host_layout(const struct domain *d)
+{
+    return paging_mode_translate(d) &&
+           (is_domain_direct_mapped(d) || is_hardware_domain(d));
+}
+
+#endif /* XEN_DOMAIN_LAYOUT_H */
--
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