[PATCH v8 2/8] xen/arm: Split MMU system SMP MM bringup code to mmu/smpboot.c

[Henry Wang <Henry.Wang@xxxxxxx>]

Move the code related to secondary page table initialization, clear
boot page tables and the global variable definitions of these boot
page tables from arch/arm/mm.c to arch/arm/mmu/smpboot.c

Since arm32 global variable cpu0_pgtable will be used by both
arch/arm/mm.c and arch/arm/mmu/smpboot.c, to avoid exporting this
variable, change the variable usage in arch/arm/mmu/smpboot.c to
per_cpu(xen_pgtable, 0).

To avoid exposing global variable phys_offset, use virt_to_maddr()
to calculate init_ttbr for arm64.

Take the opportunity to fix the in-code comment coding styles when
possible.

Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>
Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
---
v8:
- Drop the unnecessary cast in virt_to_maddr((uintptr_t) xen_pgtable);
- Add Julien's Reviewed-by tag.
v7:
- Do not export cpu0_pgtable, replace the variable usage in
  arch/arm/mmu/smpboot.c to per_cpu(xen_pgtable, 0).
- Also move global variable init_ttbr to arch/arm/mmu/smpboot.c.
- Use virt_to_maddr() instead of phys_offset to calculate init_ttbr
  in arm64 implementation of init_secondary_pagetables().
v6:
- Rework the original patch "[v5,07/13] xen/arm: Extract MMU-specific
  code", only split the smpboot related code out in this patch.
---
 xen/arch/arm/mm.c          | 104 -------------------------------
 xen/arch/arm/mmu/Makefile  |   1 +
 xen/arch/arm/mmu/smpboot.c | 124 +++++++++++++++++++++++++++++++++++++
 3 files changed, 125 insertions(+), 104 deletions(-)
 create mode 100644 xen/arch/arm/mmu/smpboot.c

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index fd02493564..b7eb3a6e08 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -27,39 +27,6 @@
 #undef mfn_to_virt
 #define mfn_to_virt(mfn) __mfn_to_virt(mfn_x(mfn))
 
-/* Static start-of-day pagetables that we use before the allocators
- * are up. These are used by all CPUs during bringup before switching
- * to the CPUs own pagetables.
- *
- * These pagetables have a very simple structure. They include:
- *  - XEN_VIRT_SIZE worth of L3 mappings of xen at XEN_VIRT_START, boot_first
- *    and boot_second are used to populate the tables down to boot_third
- *    which contains the actual mapping.
- *  - a 1:1 mapping of xen at its current physical address. This uses a
- *    section mapping at whichever of boot_{pgtable,first,second}
- *    covers that physical address.
- *
- * For the boot CPU these mappings point to the address where Xen was
- * loaded by the bootloader. For secondary CPUs they point to the
- * relocated copy of Xen for the benefit of secondary CPUs.
- *
- * In addition to the above for the boot CPU the device-tree is
- * initially mapped in the boot misc slot. This mapping is not present
- * for secondary CPUs.
- *
- * Finally, if EARLY_PRINTK is enabled then xen_fixmap will be mapped
- * by the CPU once it has moved off the 1:1 mapping.
- */
-DEFINE_BOOT_PAGE_TABLE(boot_pgtable);
-#ifdef CONFIG_ARM_64
-DEFINE_BOOT_PAGE_TABLE(boot_first);
-DEFINE_BOOT_PAGE_TABLE(boot_first_id);
-#endif
-DEFINE_BOOT_PAGE_TABLE(boot_second_id);
-DEFINE_BOOT_PAGE_TABLE(boot_third_id);
-DEFINE_BOOT_PAGE_TABLE(boot_second);
-DEFINE_BOOT_PAGE_TABLES(boot_third, XEN_NR_ENTRIES(2));
-
 /* Main runtime page tables */
 
 /*
@@ -94,9 +61,6 @@ DEFINE_BOOT_PAGE_TABLE(xen_fixmap);
  */
 static DEFINE_PAGE_TABLES(xen_xenmap, XEN_NR_ENTRIES(2));
 
-/* Non-boot CPUs use this to find the correct pagetables. */
-uint64_t init_ttbr;
-
 static paddr_t phys_offset;
 
 /* Limits of the Xen heap */
@@ -284,13 +248,6 @@ static void xen_pt_enforce_wnx(void)
     flush_xen_tlb_local();
 }
 
-/* Clear a translation table and clean & invalidate the cache */
-static void clear_table(void *table)
-{
-    clear_page(table);
-    clean_and_invalidate_dcache_va_range(table, PAGE_SIZE);
-}
-
 /* Boot-time pagetable setup.
  * Changes here may need matching changes in head.S */
 void __init setup_pagetables(unsigned long boot_phys_offset)
@@ -369,67 +326,6 @@ void __init setup_pagetables(unsigned long 
boot_phys_offset)
 #endif
 }
 
-static void clear_boot_pagetables(void)
-{
-    /*
-     * Clear the copy of the boot pagetables. Each secondary CPU
-     * rebuilds these itself (see head.S).
-     */
-    clear_table(boot_pgtable);
-#ifdef CONFIG_ARM_64
-    clear_table(boot_first);
-    clear_table(boot_first_id);
-#endif
-    clear_table(boot_second);
-    clear_table(boot_third);
-}
-
-#ifdef CONFIG_ARM_64
-int init_secondary_pagetables(int cpu)
-{
-    clear_boot_pagetables();
-
-    /* Set init_ttbr for this CPU coming up. All CPus share a single setof
-     * pagetables, but rewrite it each time for consistency with 32 bit. */
-    init_ttbr = (uintptr_t) xen_pgtable + phys_offset;
-    clean_dcache(init_ttbr);
-    return 0;
-}
-#else
-int init_secondary_pagetables(int cpu)
-{
-    lpae_t *first;
-
-    first = alloc_xenheap_page(); /* root == first level on 32-bit 3-level 
trie */
-
-    if ( !first )
-    {
-        printk("CPU%u: Unable to allocate the first page-table\n", cpu);
-        return -ENOMEM;
-    }
-
-    /* Initialise root pagetable from root of boot tables */
-    memcpy(first, cpu0_pgtable, PAGE_SIZE);
-    per_cpu(xen_pgtable, cpu) = first;
-
-    if ( !init_domheap_mappings(cpu) )
-    {
-        printk("CPU%u: Unable to prepare the domheap page-tables\n", cpu);
-        per_cpu(xen_pgtable, cpu) = NULL;
-        free_xenheap_page(first);
-        return -ENOMEM;
-    }
-
-    clear_boot_pagetables();
-
-    /* Set init_ttbr for this CPU coming up */
-    init_ttbr = __pa(first);
-    clean_dcache(init_ttbr);
-
-    return 0;
-}
-#endif
-
 /* MMU setup for secondary CPUS (which already have paging enabled) */
 void mmu_init_secondary_cpu(void)
 {
diff --git a/xen/arch/arm/mmu/Makefile b/xen/arch/arm/mmu/Makefile
index bdfc2e077d..0e82015ee1 100644
--- a/xen/arch/arm/mmu/Makefile
+++ b/xen/arch/arm/mmu/Makefile
@@ -1 +1,2 @@
 obj-y += pt.o
+obj-y += smpboot.o
diff --git a/xen/arch/arm/mmu/smpboot.c b/xen/arch/arm/mmu/smpboot.c
new file mode 100644
index 0000000000..8b6a09f843
--- /dev/null
+++ b/xen/arch/arm/mmu/smpboot.c
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * xen/arch/arm/mmu/smpboot.c
+ *
+ * MMU system secondary CPUs MM bringup code.
+ */
+
+#include <xen/domain_page.h>
+
+/*
+ * Static start-of-day pagetables that we use before the allocators
+ * are up. These are used by all CPUs during bringup before switching
+ * to the CPUs own pagetables.
+ *
+ * These pagetables have a very simple structure. They include:
+ *  - XEN_VIRT_SIZE worth of L3 mappings of xen at XEN_VIRT_START, boot_first
+ *    and boot_second are used to populate the tables down to boot_third
+ *    which contains the actual mapping.
+ *  - a 1:1 mapping of xen at its current physical address. This uses a
+ *    section mapping at whichever of boot_{pgtable,first,second}
+ *    covers that physical address.
+ *
+ * For the boot CPU these mappings point to the address where Xen was
+ * loaded by the bootloader. For secondary CPUs they point to the
+ * relocated copy of Xen for the benefit of secondary CPUs.
+ *
+ * In addition to the above for the boot CPU the device-tree is
+ * initially mapped in the boot misc slot. This mapping is not present
+ * for secondary CPUs.
+ *
+ * Finally, if EARLY_PRINTK is enabled then xen_fixmap will be mapped
+ * by the CPU once it has moved off the 1:1 mapping.
+ */
+DEFINE_BOOT_PAGE_TABLE(boot_pgtable);
+#ifdef CONFIG_ARM_64
+DEFINE_BOOT_PAGE_TABLE(boot_first);
+DEFINE_BOOT_PAGE_TABLE(boot_first_id);
+#endif
+DEFINE_BOOT_PAGE_TABLE(boot_second_id);
+DEFINE_BOOT_PAGE_TABLE(boot_third_id);
+DEFINE_BOOT_PAGE_TABLE(boot_second);
+DEFINE_BOOT_PAGE_TABLES(boot_third, XEN_NR_ENTRIES(2));
+
+/* Non-boot CPUs use this to find the correct pagetables. */
+uint64_t init_ttbr;
+
+/* Clear a translation table and clean & invalidate the cache */
+static void clear_table(void *table)
+{
+    clear_page(table);
+    clean_and_invalidate_dcache_va_range(table, PAGE_SIZE);
+}
+
+static void clear_boot_pagetables(void)
+{
+    /*
+     * Clear the copy of the boot pagetables. Each secondary CPU
+     * rebuilds these itself (see head.S).
+     */
+    clear_table(boot_pgtable);
+#ifdef CONFIG_ARM_64
+    clear_table(boot_first);
+    clear_table(boot_first_id);
+#endif
+    clear_table(boot_second);
+    clear_table(boot_third);
+}
+
+#ifdef CONFIG_ARM_64
+int init_secondary_pagetables(int cpu)
+{
+    clear_boot_pagetables();
+
+    /*
+     * Set init_ttbr for this CPU coming up. All CPUs share a single setof
+     * pagetables, but rewrite it each time for consistency with 32 bit.
+     */
+    init_ttbr = virt_to_maddr(xen_pgtable);
+    clean_dcache(init_ttbr);
+    return 0;
+}
+#else
+int init_secondary_pagetables(int cpu)
+{
+    lpae_t *first;
+
+    first = alloc_xenheap_page(); /* root == first level on 32-bit 3-level 
trie */
+
+    if ( !first )
+    {
+        printk("CPU%u: Unable to allocate the first page-table\n", cpu);
+        return -ENOMEM;
+    }
+
+    /* Initialise root pagetable from root of boot tables */
+    memcpy(first, per_cpu(xen_pgtable, 0), PAGE_SIZE);
+    per_cpu(xen_pgtable, cpu) = first;
+
+    if ( !init_domheap_mappings(cpu) )
+    {
+        printk("CPU%u: Unable to prepare the domheap page-tables\n", cpu);
+        per_cpu(xen_pgtable, cpu) = NULL;
+        free_xenheap_page(first);
+        return -ENOMEM;
+    }
+
+    clear_boot_pagetables();
+
+    /* Set init_ttbr for this CPU coming up */
+    init_ttbr = __pa(first);
+    clean_dcache(init_ttbr);
+
+    return 0;
+}
+#endif
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
2.25.1