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>
diff --git a/drivers/char/hw_random/via-rng.c b/drivers/char/hw_random/via-rng.c
index 868e39f..f7feae4 100644
--- a/drivers/char/hw_random/via-rng.c
+++ b/drivers/char/hw_random/via-rng.c
@@ -42,6 +42,8 @@
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_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 @@
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);