[PATCH v3 1/3] powerpc/microwatt: wire up rng during setup_arch

[PATCH v3 1/3] powerpc/microwatt: wire up rng during setup_arch

[Jason A. Donenfeld]

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. Fortunately,
each platform already has a setup_arch function pointer, which means
it's easy to wire this up. This commit also removes some noisy log
messages that don't add much.

Cc: stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: c25769fddaec ("powerpc/microwatt: Add support for hardware random number generator")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/platforms/microwatt/microwatt.h |  7 +++++++
 arch/powerpc/platforms/microwatt/rng.c       | 10 +++-------
 arch/powerpc/platforms/microwatt/setup.c     |  8 ++++++++
 3 files changed, 18 insertions(+), 7 deletions(-)
 create mode 100644 arch/powerpc/platforms/microwatt/microwatt.h

diff --git a/arch/powerpc/platforms/microwatt/microwatt.h b/arch/powerpc/platforms/microwatt/microwatt.h
new file mode 100644
index 000000000000..335417e95e66
--- /dev/null
+++ b/arch/powerpc/platforms/microwatt/microwatt.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MICROWATT_H
+#define _MICROWATT_H
+
+void microwatt_rng_init(void);
+
+#endif /* _MICROWATT_H */
diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
index 7bc4d1cbfaf0..8ece87d005c8 100644
--- a/arch/powerpc/platforms/microwatt/rng.c
+++ b/arch/powerpc/platforms/microwatt/rng.c
@@ -11,6 +11,7 @@
 #include <asm/archrandom.h>
 #include <asm/cputable.h>
 #include <asm/machdep.h>
+#include "microwatt.h"
 
 #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
 
@@ -29,7 +30,7 @@ static int microwatt_get_random_darn(unsigned long *v)
 	return 1;
 }
 
-static __init int rng_init(void)
+void __init microwatt_rng_init(void)
 {
 	unsigned long val;
 	int i;
@@ -37,12 +38,7 @@ static __init int rng_init(void)
 	for (i = 0; i < 10; i++) {
 		if (microwatt_get_random_darn(&val)) {
 			ppc_md.get_random_seed = microwatt_get_random_darn;
-			return 0;
+			return;
 		}
 	}
-
-	pr_warn("Unable to use DARN for get_random_seed()\n");
-
-	return -EIO;
 }
-machine_subsys_initcall(, rng_init);
diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
index 0b02603bdb74..6b32539395a4 100644
--- a/arch/powerpc/platforms/microwatt/setup.c
+++ b/arch/powerpc/platforms/microwatt/setup.c
@@ -16,6 +16,8 @@
 #include <asm/xics.h>
 #include <asm/udbg.h>
 
+#include "microwatt.h"
+
 static void __init microwatt_init_IRQ(void)
 {
 	xics_init();
@@ -32,10 +34,16 @@ static int __init microwatt_populate(void)
 }
 machine_arch_initcall(microwatt, microwatt_populate);
 
+static void __init microwatt_setup_arch(void)
+{
+	microwatt_rng_init();
+}
+
 define_machine(microwatt) {
 	.name			= "microwatt",
 	.probe			= microwatt_probe,
 	.init_IRQ		= microwatt_init_IRQ,
+	.setup_arch		= microwatt_setup_arch,
 	.progress		= udbg_progress,
 	.calibrate_decr		= generic_calibrate_decr,
 };
-- 
2.35.1

Re: [PATCH v3 1/3] powerpc/microwatt: wire up rng during setup_arch

[Christophe Leroy]

Le 11/06/2022 à 17:10, Jason A. Donenfeld a écrit :
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means
> it's easy to wire this up. This commit also removes some noisy log
> messages that don't add much.
> 
> Cc: stable@vger.kernel.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Fixes: c25769fddaec ("powerpc/microwatt: Add support for hardware random number generator")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
>   arch/powerpc/platforms/microwatt/microwatt.h |  7 +++++++
>   arch/powerpc/platforms/microwatt/rng.c       | 10 +++-------
>   arch/powerpc/platforms/microwatt/setup.c     |  8 ++++++++
>   3 files changed, 18 insertions(+), 7 deletions(-)
>   create mode 100644 arch/powerpc/platforms/microwatt/microwatt.h
> 
> diff --git a/arch/powerpc/platforms/microwatt/microwatt.h b/arch/powerpc/platforms/microwatt/microwatt.h
> new file mode 100644
> index 000000000000..335417e95e66
> --- /dev/null
> +++ b/arch/powerpc/platforms/microwatt/microwatt.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _MICROWATT_H
> +#define _MICROWATT_H
> +
> +void microwatt_rng_init(void);
> +
> +#endif /* _MICROWATT_H */
> diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
> index 7bc4d1cbfaf0..8ece87d005c8 100644
> --- a/arch/powerpc/platforms/microwatt/rng.c
> +++ b/arch/powerpc/platforms/microwatt/rng.c
> @@ -11,6 +11,7 @@
>   #include <asm/archrandom.h>
>   #include <asm/cputable.h>
>   #include <asm/machdep.h>
> +#include "microwatt.h"
>   
>   #define DARN_ERR 0xFFFFFFFFFFFFFFFFul
>   
> @@ -29,7 +30,7 @@ static int microwatt_get_random_darn(unsigned long *v)
>   	return 1;
>   }
>   
> -static __init int rng_init(void)
> +void __init microwatt_rng_init(void)
>   {
>   	unsigned long val;
>   	int i;
> @@ -37,12 +38,7 @@ static __init int rng_init(void)
>   	for (i = 0; i < 10; i++) {
>   		if (microwatt_get_random_darn(&val)) {
>   			ppc_md.get_random_seed = microwatt_get_random_darn;
> -			return 0;
> +			return;
>   		}
>   	}
> -
> -	pr_warn("Unable to use DARN for get_random_seed()\n");
> -
> -	return -EIO;
>   }
> -machine_subsys_initcall(, rng_init);
> diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
> index 0b02603bdb74..6b32539395a4 100644
> --- a/arch/powerpc/platforms/microwatt/setup.c
> +++ b/arch/powerpc/platforms/microwatt/setup.c
> @@ -16,6 +16,8 @@
>   #include <asm/xics.h>
>   #include <asm/udbg.h>
>   
> +#include "microwatt.h"
> +
>   static void __init microwatt_init_IRQ(void)
>   {
>   	xics_init();
> @@ -32,10 +34,16 @@ static int __init microwatt_populate(void)
>   }
>   machine_arch_initcall(microwatt, microwatt_populate);
>   
> +static void __init microwatt_setup_arch(void)
> +{
> +	microwatt_rng_init();
> +}
> +
>   define_machine(microwatt) {
>   	.name			= "microwatt",
>   	.probe			= microwatt_probe,
>   	.init_IRQ		= microwatt_init_IRQ,
> +	.setup_arch		= microwatt_setup_arch,
>   	.progress		= udbg_progress,
>   	.calibrate_decr		= generic_calibrate_decr,
>   };

[PATCH v3 2/3] powerpc/powernv: wire up rng during setup_arch

[Jason A. Donenfeld]

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. Fortunately,
each platform already has a setup_arch function pointer, which means
it's easy to wire this up. This commit also removes some noisy log
messages that don't add much.

Cc: stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/platforms/powernv/powernv.h |  2 ++
 arch/powerpc/platforms/powernv/rng.c     | 18 +++++-------------
 arch/powerpc/platforms/powernv/setup.c   |  2 ++
 3 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index e297bf4abfcb..fd3f5e1eb10b 100644
--- 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);
 u32 __init memcons_get_size(struct memcons *mc);
 struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name);
 
+void powernv_rng_init(void);
+
 #endif /* _POWERNV_H */
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e3d44b36ae98..c86bf097e407 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
 
@@ -84,24 +85,20 @@ static int powernv_get_random_darn(unsigned long *v)
 	return 1;
 }
 
-static int __init initialise_darn(void)
+static void __init initialise_darn(void)
 {
 	unsigned long val;
 	int i;
 
 	if (!cpu_has_feature(CPU_FTR_ARCH_300))
-		return -ENODEV;
+		return;
 
 	for (i = 0; i < 10; i++) {
 		if (powernv_get_random_darn(&val)) {
 			ppc_md.get_random_seed = powernv_get_random_darn;
-			return 0;
+			return;
 		}
 	}
-
-	pr_warn("Unable to use DARN for get_random_seed()\n");
-
-	return -EIO;
 }
 
 int powernv_get_random_long(unsigned long *v)
@@ -163,14 +160,12 @@ 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)
+void __init powernv_rng_init(void)
 {
 	struct device_node *dn;
 	int rc;
@@ -188,7 +183,4 @@ static __init int rng_init(void)
 	}
 
 	initialise_darn();
-
-	return 0;
 }
-machine_subsys_initcall(powernv, rng_init);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 824c3ad7a0fa..a5fcb6796b22 100644
--- 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)
 	pnv_check_guarded_cores();
 
 	/* XXX PMCS */
+
+	powernv_rng_init();
 }
 
 static void __init pnv_init(void)
-- 
2.35.1

Re: [PATCH v3 2/3] powerpc/powernv: wire up rng during setup_arch

[Christophe Leroy]

Le 11/06/2022 à 17:10, Jason A. Donenfeld a écrit :
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means
> it's easy to wire this up. This commit also removes some noisy log
> messages that don't add much.
> 
> Cc: stable@vger.kernel.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
>   arch/powerpc/platforms/powernv/powernv.h |  2 ++
>   arch/powerpc/platforms/powernv/rng.c     | 18 +++++-------------
>   arch/powerpc/platforms/powernv/setup.c   |  2 ++
>   3 files changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
> index e297bf4abfcb..fd3f5e1eb10b 100644
> --- 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);
>   u32 __init memcons_get_size(struct memcons *mc);
>   struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name);
>   
> +void powernv_rng_init(void);
> +
>   #endif /* _POWERNV_H */
> diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
> index e3d44b36ae98..c86bf097e407 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
>   
> @@ -84,24 +85,20 @@ static int powernv_get_random_darn(unsigned long *v)
>   	return 1;
>   }
>   
> -static int __init initialise_darn(void)
> +static void __init initialise_darn(void)
>   {
>   	unsigned long val;
>   	int i;
>   
>   	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> -		return -ENODEV;
> +		return;
>   
>   	for (i = 0; i < 10; i++) {
>   		if (powernv_get_random_darn(&val)) {
>   			ppc_md.get_random_seed = powernv_get_random_darn;
> -			return 0;
> +			return;
>   		}
>   	}
> -
> -	pr_warn("Unable to use DARN for get_random_seed()\n");
> -
> -	return -EIO;
>   }
>   
>   int powernv_get_random_long(unsigned long *v)
> @@ -163,14 +160,12 @@ 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)
> +void __init powernv_rng_init(void)
>   {
>   	struct device_node *dn;
>   	int rc;
> @@ -188,7 +183,4 @@ static __init int rng_init(void)
>   	}
>   
>   	initialise_darn();
> -
> -	return 0;
>   }
> -machine_subsys_initcall(powernv, rng_init);
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index 824c3ad7a0fa..a5fcb6796b22 100644
> --- 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)
>   	pnv_check_guarded_cores();
>   
>   	/* XXX PMCS */
> +
> +	powernv_rng_init();
>   }
>   
>   static void __init pnv_init(void)

Re: [PATCH v3 2/3] powerpc/powernv: wire up rng during setup_arch

[Michael Ellerman]

"Jason A. Donenfeld" <Jason@zx2c4.com> writes:
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means
> it's easy to wire this up. This commit also removes some noisy log
> messages that don't add much.
>
> Cc: stable@vger.kernel.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
>  arch/powerpc/platforms/powernv/powernv.h |  2 ++
>  arch/powerpc/platforms/powernv/rng.c     | 18 +++++-------------
>  arch/powerpc/platforms/powernv/setup.c   |  2 ++
>  3 files changed, 9 insertions(+), 13 deletions(-)
>
...
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index 824c3ad7a0fa..a5fcb6796b22 100644
> --- 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)
>  	pnv_check_guarded_cores();
>  
>  	/* XXX PMCS */
> +
> +	powernv_rng_init();
>  }

This crashes on power8 because it's too early to call kzalloc() in
rng_create(), and it's also too early to setup the percpu variables in
there.

I'll rework it and post a v4.

cheers

Re: [PATCH v3 2/3] powerpc/powernv: wire up rng during setup_arch

[Jason A. Donenfeld]

Hi Michael,

On Sun, Jun 19, 2022 at 1:49 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
> This crashes on power8 because it's too early to call kzalloc() in
> rng_create(), and it's also too early to setup the percpu variables in
> there.
>
> I'll rework it and post a v4.

Oh, darn. Sorry about that. Thanks for reworking it.

Jason

[PATCH v4] powerpc/powernv: wire up rng during setup_arch

[Jason A. Donenfeld]

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. Fortunately,
each platform already has a setup_arch function pointer, which means we
can wire it up that way. 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 into an early phase and a late phase,
with the early phase working well enough to seed the RNG with a
spinlock, before later getting fast per-cpu allocations. This commit
also removes some noisy log messages that don't add much.

Cc: stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/platforms/powernv/powernv.h |  2 +
 arch/powerpc/platforms/powernv/rng.c     | 68 ++++++++++++++++++------
 arch/powerpc/platforms/powernv/setup.c   |  2 +
 3 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index e297bf4abfcb..fd3f5e1eb10b 100644
--- 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);
 u32 __init memcons_get_size(struct memcons *mc);
 struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name);
 
+void powernv_rng_init(void);
+
 #endif /* _POWERNV_H */
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e3d44b36ae98..c1beced9c32c 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
 
@@ -28,6 +29,12 @@ struct powernv_rng {
 
 static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
 
+static struct {
+	struct powernv_rng rng;
+	spinlock_t lock;
+} early_state __initdata = {
+	.lock = __SPIN_LOCK_UNLOCKED(powernv_early_rng)
+};
 
 int powernv_hwrng_present(void)
 {
@@ -84,7 +91,7 @@ static int powernv_get_random_darn(unsigned long *v)
 	return 1;
 }
 
-static int __init initialise_darn(void)
+static int __init initialize_darn(void)
 {
 	unsigned long val;
 	int i;
@@ -98,10 +105,18 @@ static int __init initialise_darn(void)
 			return 0;
 		}
 	}
+	return -EIO;
+}
 
-	pr_warn("Unable to use DARN for get_random_seed()\n");
+static int __init powernv_get_random_long_early(unsigned long *v)
+{
+	unsigned long flags;
 
-	return -EIO;
+	spin_lock_irqsave(&early_state.lock, flags);
+	*v = rng_whiten(&early_state.rng, in_be64(early_state.rng.regs));
+	spin_unlock_irqrestore(&early_state.lock, flags);
+
+	return 1;
 }
 
 int powernv_get_random_long(unsigned long *v)
@@ -163,32 +178,51 @@ 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)
+void __init powernv_rng_init(void)
+{
+	struct device_node *dn;
+	struct resource res;
+
+	/* Prefer darn over the rest. */
+	if (!initialize_darn())
+		return;
+
+	dn = of_find_compatible_node(NULL, NULL, "ibm,power-rng");
+	if (!dn)
+		return;
+	if (of_address_to_resource(dn, 0, &res))
+		return;
+	early_state.rng.regs_real = (void __iomem *)res.start;
+	early_state.rng.regs = of_iomap(dn, 0);
+	if (!early_state.rng.regs)
+		return;
+	early_state.rng.mask = in_be64(early_state.rng.regs);
+	ppc_md.get_random_seed = powernv_get_random_long_early;
+}
+
+static __init int powernv_rng_late_init(void)
 {
 	struct device_node *dn;
-	int rc;
+
+	/*
+	 * If this didn't get initialized early on, then we're using darn,
+	 * or this isn't available at all, so return early.
+	 */
+	if (ppc_md.get_random_seed != powernv_get_random_long_early)
+		return 0;
+	ppc_md.get_random_seed = NULL;
 
 	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();
-
 	return 0;
 }
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, powernv_rng_late_init);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 824c3ad7a0fa..a5fcb6796b22 100644
--- 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)
 	pnv_check_guarded_cores();
 
 	/* XXX PMCS */
+
+	powernv_rng_init();
 }
 
 static void __init pnv_init(void)
-- 
2.35.1

[PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Jason A. Donenfeld]

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. Fortunately,
each platform already has a setup_arch function pointer, which means we
can wire it up that way. 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.

Cc: stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: a4da0d50b2a0 ("powerpc: Implement arch_get_random_long/int() for powernv")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/platforms/powernv/powernv.h |  2 +
 arch/powerpc/platforms/powernv/rng.c     | 47 ++++++++++++++++--------
 arch/powerpc/platforms/powernv/setup.c   |  2 +
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h
index e297bf4abfcb..fd3f5e1eb10b 100644
--- 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);
 u32 __init memcons_get_size(struct memcons *mc);
 struct memcons *__init memcons_init(struct device_node *node, const char *mc_prop_name);
 
+void powernv_rng_init(void);
+
 #endif /* _POWERNV_H */
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index e3d44b36ae98..e332e72e1857 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 +160,50 @@ 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 powernv_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, powernv_get_random_long_early,
+		    NULL) != powernv_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 powernv_rng_init(void)
+{
+	/* Prefer darn over the rest. */
+	if (!initialise_darn())
+		return;
+
+	if (of_find_compatible_node(NULL, NULL, "ibm,power-rng"))
+		ppc_md.get_random_seed = powernv_get_random_long_early;
+}
 
+static int __init powernv_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 == powernv_get_random_long_early)
+		powernv_get_random_long_early(&v);
 	return 0;
 }
-machine_subsys_initcall(powernv, rng_init);
+machine_subsys_initcall(powernv, powernv_rng_late_init);
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index 824c3ad7a0fa..a5fcb6796b22 100644
--- 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)
 	pnv_check_guarded_cores();
 
 	/* XXX PMCS */
+
+	powernv_rng_init();
 }
 
 static void __init pnv_init(void)
-- 
2.35.1

Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Christophe Leroy]

Le 21/06/2022 à 16:08, Jason A. Donenfeld a écrit :
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means we
> can wire it up that way. 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.

Regarding the kmalloc(), I have not looked at it in details, but usually 
you can use memblock_alloc() when kmalloc is not available yet.

Christophe

Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Jason A. Donenfeld]

Hi Christophe,

On Tue, Jun 21, 2022 at 06:33:11PM +0000, Christophe Leroy wrote:
> Le 21/06/2022 à 16:08, Jason A. Donenfeld a écrit :
> > 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. Fortunately,
> > each platform already has a setup_arch function pointer, which means we
> > can wire it up that way. 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.
> 
> Regarding the kmalloc(), I have not looked at it in details, but usually 
> you can use memblock_alloc() when kmalloc is not available yet.

That seems a bit excessive, especially as those allocations are long
lived. And we don't even *need* it that early, but just before
random_init(). Michael is running this v5 on the test rig overnight, so
we'll learn in the Australian morning whether this finally did the trick
(I hope).

Jason

Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Christophe Leroy]

Le 21/06/2022 à 20:47, Jason A. Donenfeld a écrit :
> Hi Christophe,
> 
> On Tue, Jun 21, 2022 at 06:33:11PM +0000, Christophe Leroy wrote:
>> Le 21/06/2022 à 16:08, Jason A. Donenfeld a écrit :
>>> 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. Fortunately,
>>> each platform already has a setup_arch function pointer, which means we
>>> can wire it up that way. 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.
>>
>> Regarding the kmalloc(), I have not looked at it in details, but usually
>> you can use memblock_alloc() when kmalloc is not available yet.
> 
> That seems a bit excessive, especially as those allocations are long
> lived. And we don't even *need* it that early, but just before
> random_init(). Michael is running this v5 on the test rig overnight, so
> we'll learn in the Australian morning whether this finally did the trick
> (I hope).
> 

The fact that they are long lived make them a good candidate for 
memblock_alloc().

But fair enough, if they are not required that early then just do it later.

Christophe

Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Michael Ellerman]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 21/06/2022 à 20:47, Jason A. Donenfeld a écrit :
>> On Tue, Jun 21, 2022 at 06:33:11PM +0000, Christophe Leroy wrote:
>>> Le 21/06/2022 à 16:08, Jason A. Donenfeld a écrit :
>>>> 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. Fortunately,
>>>> each platform already has a setup_arch function pointer, which means we
>>>> can wire it up that way. 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.
>>>
>>> Regarding the kmalloc(), I have not looked at it in details, but usually
>>> you can use memblock_alloc() when kmalloc is not available yet.
>> 
>> That seems a bit excessive, especially as those allocations are long
>> lived. And we don't even *need* it that early, but just before
>> random_init(). Michael is running this v5 on the test rig overnight, so
>> we'll learn in the Australian morning whether this finally did the trick
>> (I hope).
>
> The fact that they are long lived make them a good candidate for 
> memblock_alloc().
>
> But fair enough, if they are not required that early then just do it later.

memblock works but then we trip on ioremap vs early_ioremap.

Fixing that is a bit of a pain as we'd have to stop using of_iomap() and
we'd also need to switch the mappings to ioremap() later in boot.

We'd also have to defer the percpu initialisation.

So it's all just a bit of a pain when we actually only need to get the
hook ready before random_init() which is called much later in boot when
slab/ioremap/percpu are all ready.

cheers

Re: [PATCH v5] powerpc/powernv: wire up rng during setup_arch

[Michael Ellerman]

On Tue, 21 Jun 2022 16:08:49 +0200, Jason A. Donenfeld wrote:
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means we
> can wire it up that way. 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.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/powernv: wire up rng during setup_arch
      https://git.kernel.org/powerpc/c/f3eac426657d985b97c92fa5f7ae1d43f04721f3

cheers

[PATCH v3 3/3] powerpc/pseries: wire up rng during setup_arch

[Jason A. Donenfeld]

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. Fortunately,
each platform already has a setup_arch function pointer, which means
it's easy to wire this up. This commit also removes some noisy log
messages that don't add much.

Cc: stable@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: a489043f4626 ("powerpc/pseries: Implement arch_get_random_long() based on H_RANDOM")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 arch/powerpc/platforms/pseries/pseries.h |  2 ++
 arch/powerpc/platforms/pseries/rng.c     | 11 +++--------
 arch/powerpc/platforms/pseries/setup.c   |  1 +
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
index f5c916c839c9..1d75b7742ef0 100644
--- a/arch/powerpc/platforms/pseries/pseries.h
+++ b/arch/powerpc/platforms/pseries/pseries.h
@@ -122,4 +122,6 @@ void pseries_lpar_read_hblkrm_characteristics(void);
 static inline void pseries_lpar_read_hblkrm_characteristics(void) { }
 #endif
 
+void pseries_rng_init(void);
+
 #endif /* _PSERIES_PSERIES_H */
diff --git a/arch/powerpc/platforms/pseries/rng.c b/arch/powerpc/platforms/pseries/rng.c
index 6268545947b8..6ddfdeaace9e 100644
--- a/arch/powerpc/platforms/pseries/rng.c
+++ b/arch/powerpc/platforms/pseries/rng.c
@@ -10,6 +10,7 @@
 #include <asm/archrandom.h>
 #include <asm/machdep.h>
 #include <asm/plpar_wrappers.h>
+#include "pseries.h"
 
 
 static int pseries_get_random_long(unsigned long *v)
@@ -24,19 +25,13 @@ static int pseries_get_random_long(unsigned long *v)
 	return 0;
 }
 
-static __init int rng_init(void)
+void __init pseries_rng_init(void)
 {
 	struct device_node *dn;
 
 	dn = of_find_compatible_node(NULL, NULL, "ibm,random");
 	if (!dn)
-		return -ENODEV;
-
-	pr_info("Registering arch random hook.\n");
-
+		return;
 	ppc_md.get_random_seed = pseries_get_random_long;
-
 	of_node_put(dn);
-	return 0;
 }
-machine_subsys_initcall(pseries, rng_init);
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index afb074269b42..ee4f1db49515 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -839,6 +839,7 @@ static void __init pSeries_setup_arch(void)
 	}
 
 	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
+	pseries_rng_init();
 }
 
 static void pseries_panic(char *str)
-- 
2.35.1

Re: [PATCH v3 3/3] powerpc/pseries: wire up rng during setup_arch

[Christophe Leroy]

Le 11/06/2022 à 17:10, Jason A. Donenfeld a écrit :
> 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. Fortunately,
> each platform already has a setup_arch function pointer, which means
> it's easy to wire this up. This commit also removes some noisy log
> messages that don't add much.
> 
> Cc: stable@vger.kernel.org
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
> Fixes: a489043f4626 ("powerpc/pseries: Implement arch_get_random_long() based on H_RANDOM")
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>

> ---
>   arch/powerpc/platforms/pseries/pseries.h |  2 ++
>   arch/powerpc/platforms/pseries/rng.c     | 11 +++--------
>   arch/powerpc/platforms/pseries/setup.c   |  1 +
>   3 files changed, 6 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h
> index f5c916c839c9..1d75b7742ef0 100644
> --- a/arch/powerpc/platforms/pseries/pseries.h
> +++ b/arch/powerpc/platforms/pseries/pseries.h
> @@ -122,4 +122,6 @@ void pseries_lpar_read_hblkrm_characteristics(void);
>   static inline void pseries_lpar_read_hblkrm_characteristics(void) { }
>   #endif
>   
> +void pseries_rng_init(void);
> +
>   #endif /* _PSERIES_PSERIES_H */
> diff --git a/arch/powerpc/platforms/pseries/rng.c b/arch/powerpc/platforms/pseries/rng.c
> index 6268545947b8..6ddfdeaace9e 100644
> --- a/arch/powerpc/platforms/pseries/rng.c
> +++ b/arch/powerpc/platforms/pseries/rng.c
> @@ -10,6 +10,7 @@
>   #include <asm/archrandom.h>
>   #include <asm/machdep.h>
>   #include <asm/plpar_wrappers.h>
> +#include "pseries.h"
>   
>   
>   static int pseries_get_random_long(unsigned long *v)
> @@ -24,19 +25,13 @@ static int pseries_get_random_long(unsigned long *v)
>   	return 0;
>   }
>   
> -static __init int rng_init(void)
> +void __init pseries_rng_init(void)
>   {
>   	struct device_node *dn;
>   
>   	dn = of_find_compatible_node(NULL, NULL, "ibm,random");
>   	if (!dn)
> -		return -ENODEV;
> -
> -	pr_info("Registering arch random hook.\n");
> -
> +		return;
>   	ppc_md.get_random_seed = pseries_get_random_long;
> -
>   	of_node_put(dn);
> -	return 0;
>   }
> -machine_subsys_initcall(pseries, rng_init);
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index afb074269b42..ee4f1db49515 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -839,6 +839,7 @@ static void __init pSeries_setup_arch(void)
>   	}
>   
>   	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
> +	pseries_rng_init();
>   }
>   
>   static void pseries_panic(char *str)