powerpc/powernv: wire up rng during setup_arch

commit f3eac426657d985b97c92fa5f7ae1d43f04721f3 upstream.

The platform's RNG must be available before random_init() in order to be
useful for initial seeding, which in turn means that it needs to be
called from setup_arch(), rather than from an init call.

Complicating things, however, is that POWER8 systems need some per-cpu
state and kmalloc, which isn't available at this stage. So we split
things up into an early phase and a later opportunistic phase. This
commit also removes some noisy log messages that don't add much.

Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Add of_node_put(), use pnv naming, minor change log editing]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220621140849.127227-1-Jason@zx2c4.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index fd4a1c5a6369f4b307633f8f79697dc3f17098ac..cd9180cc0e133475aca6de53c6b481b9325d9c47 100644 (file)
--- a/arch/powerpc/platforms/powernv/powernv.h
+++ b/arch/powerpc/platforms/powernv/powernv.h
@@ -30,4 +30,6 @@ extern void opal_event_shutdown(void);
 
 bool cpu_core_split_required(void);
 
+void pnv_rng_init(void);
+
 #endif /* _POWERNV_H */

diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e15dd09f71dfbd2978588e3434350b9d8179e606..c5c1d5cd7b10d2a118e17bb4e4801d5315be905d 100644 (file)
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -21,6 +21,7 @@
 #include <asm/prom.h>
 #include <asm/machdep.h>
 #include <asm/smp.h>
+#include "powernv.h"
 
 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
 
@@ -32,7 +33,6 @@ struct powernv_rng {
 
 static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
 
-
 int powernv_hwrng_present(void)
 {
        struct powernv_rng *rng;
@@ -102,9 +102,6 @@ static int initialise_darn(void)
                        return 0;
                }
        }
-
-       pr_warn("Unable to use DARN for get_random_seed()\n");
-
        return -EIO;
 }
 
@@ -167,32 +164,55 @@ static __init int rng_create(struct device_node *dn)
 
        rng_init_per_cpu(rng, dn);
 
-       pr_info_once("Registering arch random hook.\n");
-
        ppc_md.get_random_seed = powernv_get_random_long;
 
        return 0;
 }
 
-static __init int rng_init(void)
+static int __init pnv_get_random_long_early(unsigned long *v)
 {
        struct device_node *dn;
-       int rc;
+
+       if (!slab_is_available())
+               return 0;
+
+       if (cmpxchg(&ppc_md.get_random_seed, pnv_get_random_long_early,
+                   NULL) != pnv_get_random_long_early)
+               return 0;
 
        for_each_compatible_node(dn, NULL, "ibm,power-rng") {
-               rc = rng_create(dn);
-               if (rc) {
-                       pr_err("Failed creating rng for %pOF (%d).\n",
-                               dn, rc);
+               if (rng_create(dn))
                        continue;
-               }
-
                /* Create devices for hwrng driver */
                of_platform_device_create(dn, NULL, NULL);
        }
 
-       initialise_darn();
+       if (!ppc_md.get_random_seed)
+               return 0;
+       return ppc_md.get_random_seed(v);
+}
+
+void __init pnv_rng_init(void)
+{
+       struct device_node *dn;
 
+       /* Prefer darn over the rest. */
+       if (!initialise_darn())
+               return;
+
+       dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
+       if (dn)
+               ppc_md.get_random_seed = pnv_get_random_long_early;
+
+       of_node_put(dn);
+}
+
+static int __init pnv_rng_late_init(void)
+{
+       unsigned long v;
+       /* In case it wasn't called during init for some other reason. */
+       if (ppc_md.get_random_seed == pnv_get_random_long_early)
+               pnv_get_random_long_early(&v);
        return 0;
 }
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, pnv_rng_late_init);

diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 5068dd7f6e74b0b88670f757a6c157001f7b9acc..0ade08dd0ea27d65c85839d6ad83478ec45ba6d1 100644 (file)
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -171,6 +171,8 @@ static void __init pnv_setup_arch(void)
        powersave_nap = 1;
 
        /* XXX PMCS */
+
+       pnv_rng_init();
 }
 
 static void __init pnv_init(void)