[PATCH 1/4] powerpc/mmu: do MMU type discovery before crashkernel reservation

[Sourabh Jain <sourabhjain@linux.ibm.com>]

Crashkernel reservation on high memory depends on the MMU type, so
finalize the MMU type before calling arch_reserve_crashkernel().

With the changes introduced here, early_radix_enabled() becomes usable
and will be used in arch_reserve_crashkernel() in the upcoming patch.

early_radix_enabled() depends on cur_cpu_spec->mmu_features to find
out if the radix MMU is enabled. The radix MMU bit in mmu_features is
discovered from the FDT and kernel configs. To make sure the MMU type is
finalized before arch_reserve_crashkernel() is called, the function that
scans the FDT and sets mmu_features, along with some bits from
mmu_early_type_finalize(), has been moved above
arch_reserve_crashkernel().

Cc: Baoquan he <bhe@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shivang Upadhyay <shivangu@linux.ibm.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/include/asm/book3s/64/mmu.h |  1 +
 arch/powerpc/include/asm/mmu.h           |  1 +
 arch/powerpc/kernel/prom.c               | 28 +++++++++++++-----------
 arch/powerpc/mm/init_64.c                | 27 ++++++++++++++---------
 4 files changed, 34 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
index 48631365b48c..7a3b2ff02041 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu.h
@@ -208,6 +208,7 @@ extern int mmu_vmemmap_psize;
 
 /* MMU initialization */
 void mmu_early_init_devtree(void);
+void mmu_early_type_finalize(void);
 void hash__early_init_devtree(void);
 void radix__early_init_devtree(void);
 #ifdef CONFIG_PPC_PKEY
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 5f9c5d436e17..c40dc6349e55 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -384,6 +384,7 @@ extern void early_init_mmu_secondary(void);
 extern void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 				       phys_addr_t first_memblock_size);
 static inline void mmu_early_init_devtree(void) { }
+static inline void mmu_early_type_finalize(void) { }
 
 static inline void pkey_early_init_devtree(void) {}
 
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 9ed9dde7d231..db1615f26075 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -853,6 +853,21 @@ void __init early_init_devtree(void *params)
 	if (PHYSICAL_START > MEMORY_START)
 		memblock_reserve(MEMORY_START, int_vector_size);
 	reserve_kdump_trampoline();
+
+	DBG("Scanning CPUs ...\n");
+
+	dt_cpu_ftrs_scan();
+
+	/* Retrieve CPU related informations from the flat tree
+	 * (altivec support, boot CPU ID, ...)
+	 */
+	of_scan_flat_dt(early_init_dt_scan_cpus, NULL);
+	if (boot_cpuid < 0) {
+		printk("Failed to identify boot CPU !\n");
+		BUG();
+	}
+
+	mmu_early_type_finalize();
 #if defined(CONFIG_FA_DUMP) || defined(CONFIG_PRESERVE_FA_DUMP)
 	/*
 	 * If we fail to reserve memory for firmware-assisted dump then
@@ -884,19 +899,6 @@ void __init early_init_devtree(void *params)
 	 * FIXME .. and the initrd too? */
 	move_device_tree();
 
-	DBG("Scanning CPUs ...\n");
-
-	dt_cpu_ftrs_scan();
-
-	/* Retrieve CPU related informations from the flat tree
-	 * (altivec support, boot CPU ID, ...)
-	 */
-	of_scan_flat_dt(early_init_dt_scan_cpus, NULL);
-	if (boot_cpuid < 0) {
-		printk("Failed to identify boot CPU !\n");
-		BUG();
-	}
-
 	save_fscr_to_task();
 
 #if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index b6f3ae03ca9e..cd52c1baa3bc 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -622,8 +622,10 @@ static void __init early_init_memory_block_size(void)
 	of_scan_flat_dt(probe_memory_block_size, &memory_block_size);
 }
 
-void __init mmu_early_init_devtree(void)
+
+void __init mmu_early_type_finalize(void)
 {
+
 	bool hvmode = !!(mfmsr() & MSR_HV);
 
 	/* Disable radix mode based on kernel command line. */
@@ -634,6 +636,20 @@ void __init mmu_early_init_devtree(void)
 			pr_warn("WARNING: Ignoring cmdline option disable_radix\n");
 	}
 
+	/*
+	 * Check /chosen/ibm,architecture-vec-5 if running as a guest.
+	 * When running bare-metal, we can use radix if we like
+	 * even though the ibm,architecture-vec-5 property created by
+	 * skiboot doesn't have the necessary bits set.
+	 */
+	if (!hvmode)
+		early_check_vec5();
+}
+
+void __init mmu_early_init_devtree(void)
+{
+	bool hvmode = !!(mfmsr() & MSR_HV);
+
 	of_scan_flat_dt(dt_scan_mmu_pid_width, NULL);
 	if (hvmode && !mmu_lpid_bits) {
 		if (early_cpu_has_feature(CPU_FTR_ARCH_207S))
@@ -646,15 +662,6 @@ void __init mmu_early_init_devtree(void)
 			mmu_pid_bits = 20; /* POWER9-10 */
 	}
 
-	/*
-	 * Check /chosen/ibm,architecture-vec-5 if running as a guest.
-	 * When running bare-metal, we can use radix if we like
-	 * even though the ibm,architecture-vec-5 property created by
-	 * skiboot doesn't have the necessary bits set.
-	 */
-	if (!hvmode)
-		early_check_vec5();
-
 	early_init_memory_block_size();
 
 	if (early_radix_enabled()) {
-- 
2.51.0