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Commit 66f16a24 authored by Will Deacon's avatar Will Deacon
Browse files

arm64: smp: Rework early feature mismatched detection 



Rather than add additional variables to detect specific early feature
mismatches with secondary CPUs, we can instead dedicate the upper bits
of the CPU boot status word to flag specific mismatches.

This allows us to communicate both granule and VA-size mismatches back
to the primary CPU without the need for additional book-keeping.

Tested-by: default avatarSteve Capper <steve.capper@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 68d23da4

arch/arm64/include/asm/smp.h

+10 −5
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
#define __ASM_SMP_H



/* Values for secondary_data.status */

#define CPU_STUCK_REASON_SHIFT		(8)

#define CPU_BOOT_STATUS_MASK		((1U << CPU_STUCK_REASON_SHIFT) - 1)



#define CPU_MMU_OFF			(-1)

#define CPU_BOOT_SUCCESS		(0)
@@ -27,6 +29,9 @@ 
/* Fatal system error detected by secondary CPU, crash the system */

#define CPU_PANIC_KERNEL		(3)



#define CPU_STUCK_REASON_52_BIT_VA	(1U << CPU_STUCK_REASON_SHIFT)

#define CPU_STUCK_REASON_NO_GRAN	(2U << CPU_STUCK_REASON_SHIFT)



#ifndef __ASSEMBLY__



#include <asm/percpu.h>

arch/arm64/kernel/head.S

+4 −8
Original line number Diff line number Diff line
@@ -809,13 +809,8 @@ ENTRY(__cpu_secondary_check52bitva) 
	and	x0, x0, #(0xf << ID_AA64MMFR2_LVA_SHIFT)

	cbnz	x0, 2f



	adr_l	x0, va52mismatch

	mov	w1, #1

	strb	w1, [x0]

	dmb	sy

	dc	ivac, x0	// Invalidate potentially stale cache line



	update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x0, x1

	update_early_cpu_boot_status \

		CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_52_BIT_VA, x0, x1

1:	wfe

	wfi

	b	1b
@@ -826,7 +821,8 @@ ENDPROC(__cpu_secondary_check52bitva) 


__no_granule_support:

	/* Indicate that this CPU can't boot and is stuck in the kernel */

	update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x1, x2

	update_early_cpu_boot_status \

		CPU_STUCK_IN_KERNEL | CPU_STUCK_REASON_NO_GRAN, x1, x2

1:

	wfe

	wfi

arch/arm64/kernel/smp.c

+5 −6
Original line number Diff line number Diff line
@@ -108,7 +108,6 @@ static int boot_secondary(unsigned int cpu, struct task_struct *idle) 
}



static DECLARE_COMPLETION(cpu_running);

bool va52mismatch __ro_after_init;



int __cpu_up(unsigned int cpu, struct task_struct *idle)

{
@@ -138,10 +137,6 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) 


		if (!cpu_online(cpu)) {

			pr_crit("CPU%u: failed to come online\n", cpu);



			if (IS_ENABLED(CONFIG_ARM64_USER_VA_BITS_52) && va52mismatch)

				pr_crit("CPU%u: does not support 52-bit VAs\n", cpu);



			ret = -EIO;

		}

	} else {
@@ -156,7 +151,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) 
		if (status == CPU_MMU_OFF)

			status = READ_ONCE(__early_cpu_boot_status);



		switch (status) {

		switch (status & CPU_BOOT_STATUS_MASK) {

		default:

			pr_err("CPU%u: failed in unknown state : 0x%lx\n",

					cpu, status);
@@ -170,6 +165,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) 
			pr_crit("CPU%u: may not have shut down cleanly\n", cpu);

		case CPU_STUCK_IN_KERNEL:

			pr_crit("CPU%u: is stuck in kernel\n", cpu);

			if (status & CPU_STUCK_REASON_52_BIT_VA)

				pr_crit("CPU%u: does not support 52-bit VAs\n", cpu);

			if (status & CPU_STUCK_REASON_NO_GRAN)

				pr_crit("CPU%u: does not support %luK granule \n", cpu, PAGE_SIZE / SZ_1K);

			cpus_stuck_in_kernel++;

			break;

		case CPU_PANIC_KERNEL: