From f3eac426657d985b97c92fa5f7ae1d43f04721f3 Mon Sep 17 00:00:00 2001

From: "Jason A. Donenfeld" <Jason@zx2c4.com>

Date: Tue, 21 Jun 2022 16:08:49 +0200

Subject: [PATCH] powerpc/powernv: wire up rng during setup_arch

References: bsc#1065729

Patch-mainline: v5.19-rc4

Git-commit: f3eac426657d985b97c92fa5f7ae1d43f04721f3

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

Acked-by: Michal Suchanek <msuchanek@suse.de>

---

 arch/powerpc/platforms/powernv/powernv.h |  2 +

 arch/powerpc/platforms/powernv/rng.c     | 52 ++++++++++++++++--------

 arch/powerpc/platforms/powernv/setup.c   |  2 +

 3 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h

--- a/arch/powerpc/platforms/powernv/powernv.h

+++ b/arch/powerpc/platforms/powernv/powernv.h

@@ -42,4 +42,6 @@ ssize_t memcons_copy(struct memcons *mc, char *to, loff_t pos, size_t count);

 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 e3d44b36ae98..463c78c52cc5 100644

--- a/arch/powerpc/platforms/powernv/rng.c

+++ b/arch/powerpc/platforms/powernv/rng.c

@@ -17,6 +17,7 @@

 #include <asm/prom.h>

 #include <asm/machdep.h>

 #include <asm/smp.h>

+#include "powernv.h"

 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul

@@ -28,7 +29,6 @@ struct powernv_rng {

 static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);

-

 int powernv_hwrng_present(void)

 {

 	struct powernv_rng *rng;

@@ -98,9 +98,6 @@ static int __init initialise_darn(void)

 			return 0;

 		}

 	}

-

-	pr_warn("Unable to use DARN for get_random_seed()\n");

-

 	return -EIO;

 }

@@ -163,32 +160,55 @@ 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

--- a/arch/powerpc/platforms/powernv/setup.c

+++ b/arch/powerpc/platforms/powernv/setup.c

@@ -203,6 +203,8 @@ static void __init pnv_setup_arch(void)

 	powersave_nap = 1;

 	/* XXX PMCS */

+

+	pnv_rng_init();

 }

 static void __init pnv_init(void)

-- 

2.35.3