linux-kernel - [RFC PATCH 10/12] riscv: Use pgtable_l4_enabled to output mmu type in cpuinfo

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Message-Id: <20210104195840.1593-11-alex@ghiti.fr>
Date:   Mon,  4 Jan 2021 14:58:38 -0500
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        Christoph Hellwig <hch@....de>,
        Ard Biesheuvel <ardb@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, linux-efi@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Alexandre Ghiti <alex@...ti.fr>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [RFC PATCH 10/12] riscv: Use pgtable_l4_enabled to output mmu type in cpuinfo

Now that the mmu type is determined at runtime using SATP
characteristic, use the global variable pgtable_l4_enabled to output
mmu type of the processor through /proc/cpuinfo instead of relying on
device tree infos.

Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
Reviewed-by: Anup Patel <anup@...infault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
---
 arch/riscv/include/asm/pgtable.h |  1 +
 arch/riscv/kernel/cpu.c          | 23 ++++++++++++-----------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index dd27d28f1d9e..95721016049d 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -495,6 +495,7 @@ extern char _start[];
 extern void *dtb_early_va;
 extern uintptr_t dtb_early_pa;
 extern u64 satp_mode;
+extern bool pgtable_l4_enabled;
 void setup_bootmem(void);
 void paging_init(void);
 
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 6d59e6906fdd..dea9b1c31889 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -7,6 +7,7 @@
 #include <linux/seq_file.h>
 #include <linux/of.h>
 #include <asm/smp.h>
+#include <asm/pgtable.h>
 
 /*
  * Returns the hart ID of the given device tree node, or -ENODEV if the node
@@ -70,18 +71,19 @@ static void print_isa(struct seq_file *f, const char *isa)
 	seq_puts(f, "\n");
 }
 
-static void print_mmu(struct seq_file *f, const char *mmu_type)
+static void print_mmu(struct seq_file *f)
 {
+	char sv_type[16];
+
 #if defined(CONFIG_32BIT)
-	if (strcmp(mmu_type, "riscv,sv32") != 0)
-		return;
+	strncpy(sv_type, "sv32", 5);
 #elif defined(CONFIG_64BIT)
-	if (strcmp(mmu_type, "riscv,sv39") != 0 &&
-	    strcmp(mmu_type, "riscv,sv48") != 0)
-		return;
+	if (pgtable_l4_enabled)
+		strncpy(sv_type, "sv48", 5);
+	else
+		strncpy(sv_type, "sv39", 5);
 #endif
-
-	seq_printf(f, "mmu\t\t: %s\n", mmu_type+6);
+	seq_printf(f, "mmu\t\t: %s\n", sv_type);
 }
 
 static void *c_start(struct seq_file *m, loff_t *pos)
@@ -106,14 +108,13 @@ static int c_show(struct seq_file *m, void *v)
 {
 	unsigned long cpu_id = (unsigned long)v - 1;
 	struct device_node *node = of_get_cpu_node(cpu_id, NULL);
-	const char *compat, *isa, *mmu;
+	const char *compat, *isa;
 
 	seq_printf(m, "processor\t: %lu\n", cpu_id);
 	seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id));
 	if (!of_property_read_string(node, "riscv,isa", &isa))
 		print_isa(m, isa);
-	if (!of_property_read_string(node, "mmu-type", &mmu))
-		print_mmu(m, mmu);
+	print_mmu(m);
 	if (!of_property_read_string(node, "compatible", &compat)
 	    && strcmp(compat, "riscv"))
 		seq_printf(m, "uarch\t\t: %s\n", compat);
-- 
2.20.1