linux-kernel - [RFC V3 09/13] arm64/mm: Add __cpu_secondary

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Message-Id: <1632998116-11552-10-git-send-email-anshuman.khandual@arm.com>
Date:   Thu, 30 Sep 2021 16:05:12 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     suzuki.poulose@....com, mark.rutland@....com, will@...nel.org,
        catalin.marinas@....com, maz@...nel.org, james.morse@....com,
        steven.price@....com, Anshuman Khandual <anshuman.khandual@....com>
Subject: [RFC V3 09/13] arm64/mm: Add __cpu_secondary_check52bitpa()

FEAT_LPA2 enabled systems needs to test ID_AA64MMFR0.TGRAN value to ensure
that 52 bit PA range is supported across all secondary CPUs both for 4K and
16K configs. This adds a new __cpu_secondary_check52bitva check along with
a corresponding reason code CPU_STUCK_REASON_52_BIT_PA. This will identify
the exact reason in case the system gets stuck after detecting a secondary
CPU that does not support 52 bit PA.

Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
 arch/arm64/include/asm/smp.h |  1 +
 arch/arm64/kernel/head.S     | 21 +++++++++++++++++++++
 arch/arm64/kernel/smp.c      |  2 ++
 3 files changed, 24 insertions(+)

diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index fc55f5a..e5ff305 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -22,6 +22,7 @@
 
 #define CPU_STUCK_REASON_52_BIT_VA	(UL(1) << CPU_STUCK_REASON_SHIFT)
 #define CPU_STUCK_REASON_NO_GRAN	(UL(2) << CPU_STUCK_REASON_SHIFT)
+#define CPU_STUCK_REASON_52_BIT_PA	(UL(3) << CPU_STUCK_REASON_SHIFT)
 
 #ifndef __ASSEMBLY__
 
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index ab21aac..0b48e4c 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -667,6 +667,7 @@ SYM_FUNC_START_LOCAL(secondary_startup)
 	 */
 	bl	switch_to_vhe
 	bl	__cpu_secondary_check52bitva
+	bl	__cpu_secondary_check52bitpa
 	bl	__cpu_setup			// initialise processor
 	adrp	x1, swapper_pg_dir
 	bl	__enable_mmu
@@ -770,6 +771,26 @@ SYM_FUNC_START(__cpu_secondary_check52bitva)
 2:	ret
 SYM_FUNC_END(__cpu_secondary_check52bitva)
 
+SYM_FUNC_START(__cpu_secondary_check52bitpa)
+#ifdef CONFIG_ARM64_PA_BITS_52_LPA2
+	ldr_l	x0, arm64_lpa2_enabled
+	cmp     x2, #1
+	b.ne	2f
+
+	mrs     x0, ID_AA64MMFR0_EL1
+	ubfx    x0, x0, #ID_AA64MMFR0_TGRAN_SHIFT, 4
+	cmp     x0, #ID_AA64MMFR0_TGRAN_LPA2
+	b.ge	2f
+
+	update_early_cpu_boot_status \
+		CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_52_BIT_PA, x0, x1
+1:	wfe
+	wfi
+	b	1b
+#endif
+2:	ret
+SYM_FUNC_END(__cpu_secondary_check52bitpa)
+
 SYM_FUNC_START_LOCAL(__no_granule_support)
 	/* Indicate that this CPU can't boot and is stuck in the kernel */
 	update_early_cpu_boot_status \
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 6f6ff072..a8d08d1 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -164,6 +164,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 		if (status & CPU_STUCK_REASON_NO_GRAN) {
 			pr_crit("CPU%u: does not support %luK granule\n",
 				cpu, PAGE_SIZE / SZ_1K);
+		if (status & CPU_STUCK_REASON_52_BIT_PA)
+			pr_crit("CPU%u: does not support 52-bit PAs\n", cpu);
 		}
 		cpus_stuck_in_kernel++;
 		break;
-- 
2.7.4