From 11025e855235144271a0e447e3650b203f8215f4 Mon Sep 17 00:00:00 2001
From: Dave Jones <davej@redhat.com>
Date: Wed, 6 Feb 2008 01:37:13 -0800
Subject: [PATCH] via-rng: enable secondary noise source on CPUs where it is
present
In the padlock spec:
"SRC Bits[9:8] Noise source select (I): These bits control the two noise
sources on the processor that input bits to the accumulation buffers.
On Nehemiah processors prior to stepping 8, these bits are reserved
and undefined. The default RESET state is both bits = 0."
Signed-off-by: Dave Jones <davej@redhat.com>
Tested-by: Udo van den Heuvel <udovdh@xs4all.nl>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: folkert van Heusden <folkert@vanheusden.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/char/hw_random/via-rng.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 868e39fd42e49..f7feae4ebb5e9 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -42,6 +42,8 @@ enum {
VIA_STRFILT_ENABLE = (1 << 14),
VIA_RAWBITS_ENABLE = (1 << 13),
VIA_RNG_ENABLE = (1 << 6),
+ VIA_NOISESRC1 = (1 << 8),
+ VIA_NOISESRC2 = (1 << 9),
VIA_XSTORE_CNT_MASK = 0x0F,
VIA_RNG_CHUNK_8 = 0x00, /* 64 rand bits, 64 stored bits */
@@ -119,6 +121,7 @@ static int via_rng_data_read(struct hwrng *rng, u32 *data)
static int via_rng_init(struct hwrng *rng)
{
+ struct cpuinfo_x86 *c = &cpu_data(0);
u32 lo, hi, old_lo;
/* Control the RNG via MSR. Tread lightly and pay very close
@@ -134,6 +137,17 @@ static int via_rng_init(struct hwrng *rng)
lo &= ~VIA_XSTORE_CNT_MASK;
lo &= ~(VIA_STRFILT_ENABLE | VIA_STRFILT_FAIL | VIA_RAWBITS_ENABLE);
lo |= VIA_RNG_ENABLE;
+ lo |= VIA_NOISESRC1;
+
+ /* Enable secondary noise source on CPUs where it is present. */
+
+ /* Nehemiah stepping 8 and higher */
+ if ((c->x86_model == 9) && (c->x86_mask > 7))
+ lo |= VIA_NOISESRC2;
+
+ /* Esther */
+ if (c->x86_model >= 10)
+ lo |= VIA_NOISESRC2;
if (lo != old_lo)
wrmsr(MSR_VIA_RNG, lo, hi);
--
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