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Date: Tue, 11 Feb 2020 17:48:20 -0800
From: Atish Patra <atish.patra@....com>
To: linux-kernel@...r.kernel.org
Cc: Atish Patra <atish.patra@....com>,
Albert Ou <aou@...s.berkeley.edu>,
Allison Randal <allison@...utok.net>,
Anup Patel <anup@...infault.org>, Borislav Petkov <bp@...e.de>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Jason Cooper <jason@...edaemon.net>,
Kees Cook <keescook@...omium.org>,
linux-riscv@...ts.infradead.org, Mao Han <han_mao@...ky.com>,
Marc Zyngier <maz@...nel.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Michael Ellerman <mpe@...erman.id.au>,
Mike Rapoport <rppt@...ux.ibm.com>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Thomas Gleixner <tglx@...utronix.de>,
Vincent Chen <vincent.chen@...ive.com>
Subject: [PATCH v8 09/11] RISC-V: Add supported for ordered booting method using HSM
Currently, all harts have to jump Linux in RISC-V. This complicates the
multi-stage boot process as every transient stage also has to ensure all
harts enter to that stage and jump to Linux afterwards. It also obstructs
a clean Kexec implementation.
SBI HSM extension provides alternate solutions where only a single hart
need to boot and enter Linux. The booting hart can bring up secondary
harts one by one afterwards.
Add SBI HSM based cpu_ops that implements an ordered booting method in
RISC-V. This change is also backward compatible with older firmware not
implementing HSM extension. If a latest kernel is used with older
firmware, it will continue to use the default spinning booting method.
Signed-off-by: Atish Patra <atish.patra@....com>
---
arch/riscv/kernel/cpu_ops.c | 10 +++++++++-
arch/riscv/kernel/cpu_ops_sbi.c | 31 +++++++++++++++++++++++++++++++
arch/riscv/kernel/head.S | 26 ++++++++++++++++++++++++++
arch/riscv/kernel/smpboot.c | 2 +-
arch/riscv/kernel/traps.c | 2 +-
5 files changed, 68 insertions(+), 3 deletions(-)
diff --git a/arch/riscv/kernel/cpu_ops.c b/arch/riscv/kernel/cpu_ops.c
index 1085def3735a..6221bbedaea4 100644
--- a/arch/riscv/kernel/cpu_ops.c
+++ b/arch/riscv/kernel/cpu_ops.c
@@ -18,6 +18,7 @@ const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
void *__cpu_up_stack_pointer[NR_CPUS];
void *__cpu_up_task_pointer[NR_CPUS];
+extern const struct cpu_operations cpu_ops_sbi;
extern const struct cpu_operations cpu_ops_spinwait;
void cpu_update_secondary_bootdata(unsigned int cpuid,
@@ -34,7 +35,14 @@ void cpu_update_secondary_bootdata(unsigned int cpuid,
int __init cpu_set_ops(int cpuid)
{
- cpu_ops[cpuid] = &cpu_ops_spinwait;
+#if IS_ENABLED(CONFIG_RISCV_SBI)
+ if (sbi_probe_extension(SBI_EXT_HSM) > 0) {
+ if (!cpuid)
+ pr_info("SBI v0.2 HSM extension detected\n");
+ cpu_ops[cpuid] = &cpu_ops_sbi;
+ } else
+#endif
+ cpu_ops[cpuid] = &cpu_ops_spinwait;
return 0;
}
diff --git a/arch/riscv/kernel/cpu_ops_sbi.c b/arch/riscv/kernel/cpu_ops_sbi.c
index 9bdb60e0a4df..31487a80c3b8 100644
--- a/arch/riscv/kernel/cpu_ops_sbi.c
+++ b/arch/riscv/kernel/cpu_ops_sbi.c
@@ -7,9 +7,13 @@
#include <linux/init.h>
#include <linux/mm.h>
+#include <asm/cpu_ops.h>
#include <asm/sbi.h>
#include <asm/smp.h>
+extern char secondary_start_sbi[];
+const struct cpu_operations cpu_ops_sbi;
+
static int sbi_hsm_hart_stop(void)
{
struct sbiret ret;
@@ -46,3 +50,30 @@ static int sbi_hsm_hart_get_status(unsigned long hartid)
else
return ret.value;
}
+
+static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle)
+{
+ int rc;
+ unsigned long boot_addr = __pa_symbol(secondary_start_sbi);
+ int hartid = cpuid_to_hartid_map(cpuid);
+
+ cpu_update_secondary_bootdata(cpuid, tidle);
+ rc = sbi_hsm_hart_start(hartid, boot_addr, 0);
+
+ return rc;
+}
+
+static int sbi_cpu_prepare(unsigned int cpuid)
+{
+ if (!cpu_ops_sbi.cpu_start) {
+ pr_err("cpu start method not defined for CPU [%d]\n", cpuid);
+ return -ENODEV;
+ }
+ return 0;
+}
+
+const struct cpu_operations cpu_ops_sbi = {
+ .name = "sbi",
+ .cpu_prepare = sbi_cpu_prepare,
+ .cpu_start = sbi_cpu_start,
+};
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index c1be597d22a1..8386cfafba98 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -99,11 +99,37 @@ relocate:
ret
#endif /* CONFIG_MMU */
#ifdef CONFIG_SMP
+ .global secondary_start_sbi
+secondary_start_sbi:
+ /* Mask all interrupts */
+ csrw CSR_IE, zero
+ csrw CSR_IP, zero
+
+ /* Load the global pointer */
+ .option push
+ .option norelax
+ la gp, __global_pointer$
+ .option pop
+
+ /*
+ * Disable FPU to detect illegal usage of
+ * floating point in kernel space
+ */
+ li t0, SR_FS
+ csrc CSR_STATUS, t0
+
/* Set trap vector to spin forever to help debug */
la a3, .Lsecondary_park
csrw CSR_TVEC, a3
slli a3, a0, LGREG
+ la a4, __cpu_up_stack_pointer
+ la a5, __cpu_up_task_pointer
+ add a4, a3, a4
+ add a5, a3, a5
+ REG_L sp, (a4)
+ REG_L tp, (a5)
+
.global secondary_start_common
secondary_start_common:
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 2ee41c779a16..2c56ac70e64d 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -146,7 +146,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
/*
* C entry point for a secondary processor.
*/
-asmlinkage __visible void __init smp_callin(void)
+asmlinkage __visible void smp_callin(void)
{
struct mm_struct *mm = &init_mm;
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index f4cad5163bf2..0063dd7318d6 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -147,7 +147,7 @@ int is_valid_bugaddr(unsigned long pc)
}
#endif /* CONFIG_GENERIC_BUG */
-void __init trap_init(void)
+void trap_init(void)
{
/*
* Set sup0 scratch register to 0, indicating to exception vector
--
2.24.0
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