ARM: keystone2: move update of the phys-to-virt constants into generic code

Make the init_meminfo function return the offset to be applied to the
phys-to-virt translation constants.  This allows us to move the update
into generic code, along with the requirements for this update.

This avoids platforms having to know the details of the phys-to-virt
translation support.

Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/mach/arch.h

@@ -51,7 +51,7 @@ struct machine_desc {
 	bool			(*smp_init)(void);
 	void			(*fixup)(struct tag *, char **);
 	void			(*dt_fixup)(void);
-	void			(*init_meminfo)(void);
+	long long		(*init_meminfo)(void);
 	void			(*reserve)(void);/* reserve mem blocks	*/
 	void			(*map_io)(void);/* IO mapping function	*/
 	void			(*init_early)(void);

arch/arm/mach-keystone/keystone.c

@@ -68,11 +68,9 @@ static phys_addr_t keystone_virt_to_idmap(unsigned long x)
 	return (phys_addr_t)(x) - CONFIG_PAGE_OFFSET + KEYSTONE_LOW_PHYS_START;
 }
 
-static void __init keystone_init_meminfo(void)
+static long long __init keystone_init_meminfo(void)
 {
-	bool lpae = IS_ENABLED(CONFIG_ARM_LPAE);
-	bool pvpatch = IS_ENABLED(CONFIG_ARM_PATCH_PHYS_VIRT);
-	phys_addr_t offset = PHYS_OFFSET - KEYSTONE_LOW_PHYS_START;
+	long long offset;
 	phys_addr_t mem_start, mem_end;
 
 	mem_start = memblock_start_of_DRAM();
@@ -81,29 +79,24 @@ static void __init keystone_init_meminfo(void)
 	/* nothing to do if we are running out of the <32-bit space */
 	if (mem_start >= KEYSTONE_LOW_PHYS_START &&
 	    mem_end   <= KEYSTONE_LOW_PHYS_END)
-		return;
-
-	if (!lpae || !pvpatch) {
-		pr_crit("Enable %s%s%s to run outside 32-bit space\n",
-		      !lpae ? __stringify(CONFIG_ARM_LPAE) : "",
-		      (!lpae && !pvpatch) ? " and " : "",
-		      !pvpatch ? __stringify(CONFIG_ARM_PATCH_PHYS_VIRT) : "");
-	}
+		return 0;
 
 	if (mem_start < KEYSTONE_HIGH_PHYS_START ||
 	    mem_end   > KEYSTONE_HIGH_PHYS_END) {
 		pr_crit("Invalid address space for memory (%08llx-%08llx)\n",
-		      (u64)mem_start, (u64)mem_end);
+		        (u64)mem_start, (u64)mem_end);
+		return 0;
 	}
 
-	offset += KEYSTONE_HIGH_PHYS_START;
-	__pv_phys_pfn_offset = PFN_DOWN(offset);
-	__pv_offset = (offset - PAGE_OFFSET);
+	offset = KEYSTONE_HIGH_PHYS_START - KEYSTONE_LOW_PHYS_START;
 
 	/* Populate the arch idmap hook */
 	arch_virt_to_idmap = keystone_virt_to_idmap;
 
-	pr_info("Switching to high address space at 0x%llx\n", (u64)offset);
+	pr_info("Switching to high address space at 0x%llx\n",
+	        (u64)PHYS_OFFSET + (u64)offset);
+
+	return offset;
 }
 
 static const char *const keystone_match[] __initconst = {

arch/arm/mm/mmu.c

@@ -1387,7 +1387,7 @@ static void __init map_lowmem(void)
 	}
 }
 
-#ifdef CONFIG_ARM_LPAE
+#if defined(CONFIG_ARM_LPAE) && defined(CONFIG_ARM_PATCH_PHYS_VIRT)
 /*
  * early_paging_init() recreates boot time page table setup, allowing machines
  * to switch over to a high (>4G) address space on LPAE systems
@@ -1397,6 +1397,7 @@ void __init early_paging_init(const struct machine_desc *mdesc,
 {
 	pmdval_t pmdprot = procinfo->__cpu_mm_mmu_flags;
 	unsigned long map_start, map_end;
+	long long offset;
 	pgd_t *pgd0, *pgdk;
 	pud_t *pud0, *pudk, *pud_start;
 	pmd_t *pmd0, *pmdk;
@@ -1419,7 +1420,13 @@ void __init early_paging_init(const struct machine_desc *mdesc,
 	pudk = pud_offset(pgdk, map_start);
 	pmdk = pmd_offset(pudk, map_start);
 
-	mdesc->init_meminfo();
+	offset = mdesc->init_meminfo();
+	if (offset == 0)
+		return;
+
+	/* Re-set the phys pfn offset, and the pv offset */
+	__pv_offset += offset;
+	__pv_phys_pfn_offset += PFN_DOWN(offset);
 
 	/* Run the patch stub to update the constants */
 	fixup_pv_table(&__pv_table_begin,
@@ -1502,8 +1509,19 @@ void __init early_paging_init(const struct machine_desc *mdesc,
 void __init early_paging_init(const struct machine_desc *mdesc,
 			      struct proc_info_list *procinfo)
 {
-	if (mdesc->init_meminfo)
-		mdesc->init_meminfo();
+	long long offset;
+
+	if (!mdesc->init_meminfo)
+		return;
+
+	offset = mdesc->init_meminfo();
+	if (offset == 0)
+		return;
+
+	pr_crit("Physical address space modification is only to support Keystone2.\n");
+	pr_crit("Please enable ARM_LPAE and ARM_PATCH_PHYS_VIRT support to use this\n");
+	pr_crit("feature. Your kernel may crash now, have a good day.\n");
+	add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
 }
 
 #endif