xen/riscv: introduce smp_prepare_boot_cpu()

Initialize cpu_{possible, online}_map by using smp_prepare_boot_cpu().

Drop DEFINE_PER_CPU(unsigned int, cpu_id) from stubs.c as this variable isn't
expected to be used in RISC-V at all.

Move declaration of cpu_{possible,online}_map from stubs.c to smpboot.c
as now smpboot.c is now introduced.
Other defintions keep in stubs.c as they are not initialized and not needed, at
the moment.

Drop cpu_present_map as it is enough to have cpu_possible_map. Also, ask
linker to provide symbol for cpu_present_map as common code references it.

Move call of set_processor_id(0) to smp_prepare_boot_cpu().

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/riscv/Makefile

@@ -10,6 +10,7 @@ obj-y += sbi.o
 obj-y += setup.o
 obj-y += shutdown.o
 obj-y += smp.o
+obj-y += smpboot.o
 obj-y += stubs.o
 obj-y += time.o
 obj-y += traps.o

xen/arch/riscv/setup.c

@@ -8,6 +8,7 @@
 #include <xen/init.h>
 #include <xen/mm.h>
 #include <xen/shutdown.h>
+#include <xen/smp.h>
 #include <xen/vmap.h>
 #include <xen/xvmalloc.h>
 
@@ -19,7 +20,6 @@
 #include <asm/intc.h>
 #include <asm/sbi.h>
 #include <asm/setup.h>
-#include <asm/smp.h>
 #include <asm/traps.h>
 
 /* Xen stack for bringing up the first CPU. */
@@ -72,7 +72,7 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
 
     remove_identity_mapping();
 
-    set_processor_id(0);
+    smp_prepare_boot_cpu();
 
     set_cpuid_to_hartid(0, bootcpu_id);
 

xen/arch/riscv/smpboot.c

@@ -0,0 +1,16 @@
+#include <xen/cpumask.h>
+#include <xen/init.h>
+#include <xen/sections.h>
+
+#include <asm/current.h>
+
+cpumask_t __read_mostly cpu_online_map;
+cpumask_t __ro_after_init cpu_possible_map;
+
+void __init smp_prepare_boot_cpu(void)
+{
+    set_processor_id(0);
+
+    cpumask_set_cpu(0, &cpu_possible_map);
+    cpumask_set_cpu(0, &cpu_online_map);
+}

xen/arch/riscv/stubs.c

@@ -11,12 +11,6 @@
 
 /* smpboot.c */
 
-cpumask_t cpu_online_map;
-cpumask_t cpu_present_map;
-cpumask_t cpu_possible_map;
-
-/* ID of the PCPU we're running on */
-DEFINE_PER_CPU(unsigned int, cpu_id);
 /* XXX these seem awfully x86ish... */
 /* representing HT siblings of each logical CPU */
 DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_mask);

xen/arch/riscv/xen.lds.S

@@ -165,6 +165,8 @@ SECTIONS
     ELF_DETAILS_SECTIONS
 }
 
+PROVIDE(cpu_present_map = cpu_possible_map);
+
 ASSERT(IS_ALIGNED(__bss_start,      POINTER_ALIGN), "__bss_start is misaligned")
 ASSERT(IS_ALIGNED(__bss_end,        POINTER_ALIGN), "__bss_end is misaligned")