Re: [PATCH v3 05/15] powerpc/pseries/ras: avoid calling rtas_token in NMI paths

[Christophe Leroy]

Le 07/04/2020 à 07:16, Nicholas Piggin a écrit :

In the interest of reducing code and possible failures in the
machine check and system reset paths, grab the "ibm,nmi-interlock"
token at init time.

Reviewed-by: Mahesh Salgaonkar <mah...@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>

Reviewed-by: Christophe Leroy <christophe.le...@c-s.fr>

---
  arch/powerpc/include/asm/firmware.h    |  1 +
  arch/powerpc/platforms/pseries/ras.c   |  2 +-
  arch/powerpc/platforms/pseries/setup.c | 14 ++++++++++----
  3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/firmware.h 
b/arch/powerpc/include/asm/firmware.h
index ca33f4ef6cb4..6003c2e533a0 100644
--- a/arch/powerpc/include/asm/firmware.h
+++ b/arch/powerpc/include/asm/firmware.h
@@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);

/* This is true if we are using the firmware NMI handler (typically LPAR) */

  extern int fwnmi_active;
+extern int ibm_nmi_interlock_token;

extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup; diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c

index aa6208c8d4f0..972b95ebc867 100644
--- a/arch/powerpc/platforms/pseries/ras.c
+++ b/arch/powerpc/platforms/pseries/ras.c
@@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct 
pt_regs *regs)
   */
  static void fwnmi_release_errinfo(void)
  {
-       int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
+       int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
        if (ret != 0)
                printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
  }
diff --git a/arch/powerpc/platforms/pseries/setup.c 
b/arch/powerpc/platforms/pseries/setup.c
index 0c8421dd01ab..dd234095ae4f 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << 
IOMMU_PAGE_SHIFT_4K);
  EXPORT_SYMBOL(CMO_PageSize);

int fwnmi_active; /* TRUE if an FWNMI handler is present */

+int ibm_nmi_interlock_token;

static void pSeries_show_cpuinfo(struct seq_file *m)

  {
@@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
        struct slb_entry *slb_ptr;
        size_t size;
  #endif
+       int ibm_nmi_register_token;

- int ibm_nmi_register = rtas_token("ibm,nmi-register");

-       if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
+       ibm_nmi_register_token = rtas_token("ibm,nmi-register");
+       if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
+               return;
+
+       ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
+       if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
                return;

/* If the kernel's not linked at zero we point the firmware at low

@@ -123,8 +129,8 @@ static void __init fwnmi_init(void)
        system_reset_addr  = __pa(system_reset_fwnmi) - PHYSICAL_START;
        machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;

- if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,

-                               machine_check_addr))
+       if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
+                          system_reset_addr, machine_check_addr))
                fwnmi_active = 1;

/*