[PATCH v3 23/23] xen/riscv: add initial dom0less infrastructure support

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Enable dom0less support for RISC-V by selecting HAS_DOM0LESS and
providing the minimal architecture hooks required by the common
dom0less infrastructure.

Add stub implementations for architecture-specific helpers used when
building domains from the device tree. These currently perform no
additional work but allow the generic dom0less code to build and run
on RISC-V.

Introduce max_init_domid as a runtime variable rather than a constant
so that it can be updated during dom0less domain creation.

Provide missing helpers and definitions required by the domain
construction code, including domain bitness helpers and the
p2m_set_allocation() prototype.

Additionally define the guest magic memory region in the public
RISC-V interface. GUEST_MAGIC_BASE is placed at 0x79000000 to avoid
overlapping with the QEMU RISC-V virt machine address space.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v3:
  - Add /* Nothing specific to do for now */ comment to
    arch_handle_passthrough_prop().
  - Use _ULL() instead of xen_mk_ullong() for GUEST_MAGIC_BASE and
    GUEST_MAGIC_SIZE (xen_mk_ullong() is intended for public headers only).
  - Fix GUEST_MAGIC_BASE from 0x39000000 to 0x79000000 to avoid the
    QEMU RISC-V virt machine PCIE_ECAM range.
  - Drop CONFIG_STATIC_MEMORY=n from the CI randconfig; now redundant
    since STATIC_MEMORY depends on HAS_STATIC_MEMORY which RISC-V does
    not select.
Changes in v2:
  - Move declaration of p2m_set_allocation() to p2m-common.h.
  - Add __initdata for max_init_domid and drop initalizer for it.
  - Add CONFIG_STATIC_MEMORY=n to CI's randconfig to avoid
    compilation error because of guest_physmap_add_pages()
    isn't provided.
---
 xen/arch/riscv/Kconfig                    |  2 ++
 xen/arch/riscv/dom0less-build.c           |  7 +++++++
 xen/arch/riscv/domain-build.c             | 13 +++++++++++++
 xen/arch/riscv/include/asm/guest-layout.h |  3 +++
 xen/arch/riscv/include/asm/setup.h        |  4 +++-
 xen/arch/riscv/setup.c                    |  2 ++
 6 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/xen/arch/riscv/Kconfig b/xen/arch/riscv/Kconfig
index 48520588fe40..d8a348c0cf07 100644
--- a/xen/arch/riscv/Kconfig
+++ b/xen/arch/riscv/Kconfig
@@ -6,6 +6,8 @@ config RISCV
        select GENERIC_BUG_FRAME
        select GENERIC_UART_INIT
        select HAS_DEVICE_TREE_DISCOVERY
+       select HAS_DOM0LESS
+       select HAS_DOMAIN_TYPE
        select HAS_EX_TABLE
        select HAS_PMAP
        select HAS_UBSAN
diff --git a/xen/arch/riscv/dom0less-build.c b/xen/arch/riscv/dom0less-build.c
index d1a51b92936a..0801d7e25059 100644
--- a/xen/arch/riscv/dom0less-build.c
+++ b/xen/arch/riscv/dom0less-build.c
@@ -102,3 +102,10 @@ int __init arch_parse_dom0less_node(struct dt_device_node 
*node,
 
     return 0;
 }
+
+int __init arch_handle_passthrough_prop(struct kernel_info *kinfo,
+                                        struct dt_device_node *node)
+{
+    /* Nothing specific to do for now */
+    return 0;
+}
diff --git a/xen/arch/riscv/domain-build.c b/xen/arch/riscv/domain-build.c
index 4c21ef37a6e1..df4d90e1410a 100644
--- a/xen/arch/riscv/domain-build.c
+++ b/xen/arch/riscv/domain-build.c
@@ -156,9 +156,22 @@ int __init make_cpus_node(const struct domain *d, struct 
kernel_info *kinfo)
     return fdt_end_node(fdt);
 }
 
+int __init construct_hwdom(struct kernel_info *kinfo,
+                           const struct dt_device_node *node)
+{
+    return -EOPNOTSUPP;
+}
+
 int __init make_timer_node(const struct kernel_info *kinfo)
 {
     /* There is no need for timer node for RISC-V. */
 
     return 0;
 }
+
+int __init make_hypervisor_node(struct domain *d,
+                                const struct kernel_info *kinfo,
+                                int addrcells, int sizecells)
+{
+    return -EOPNOTSUPP;
+}
diff --git a/xen/arch/riscv/include/asm/guest-layout.h 
b/xen/arch/riscv/include/asm/guest-layout.h
index 2e5762af863f..757285392d46 100644
--- a/xen/arch/riscv/include/asm/guest-layout.h
+++ b/xen/arch/riscv/include/asm/guest-layout.h
@@ -24,4 +24,7 @@
 #define GUEST_RAM_BANK_BASES   { GUEST_RAM0_BASE, GUEST_RAM1_BASE }
 #define GUEST_RAM_BANK_SIZES   { GUEST_RAM0_SIZE, GUEST_RAM1_SIZE }
 
+#define GUEST_MAGIC_BASE  _ULL(0x79000000)
+#define GUEST_MAGIC_SIZE  _ULL(0x01000000)
+
 #endif /* ASM_RISCV_GUEST_LAYOUT_H */
diff --git a/xen/arch/riscv/include/asm/setup.h 
b/xen/arch/riscv/include/asm/setup.h
index 2215894cfbb1..678b65ac1e54 100644
--- a/xen/arch/riscv/include/asm/setup.h
+++ b/xen/arch/riscv/include/asm/setup.h
@@ -5,7 +5,9 @@
 
 #include <xen/types.h>
 
-#define max_init_domid (0)
+#include <public/xen.h>
+
+extern domid_t max_init_domid;
 
 void setup_mm(void);
 
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index c3e98733ebc3..b8fa004cbf25 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -33,6 +33,8 @@
 #include <asm/traps.h>
 #include <asm/vsbi.h>
 
+domid_t __initdata max_init_domid;
+
 /* Xen stack for bringing up the first CPU. */
 unsigned char __initdata cpu0_boot_stack[STACK_SIZE]
     __aligned(STACK_SIZE);
-- 
2.54.0