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SubjectRe: [RFC PATCH] x86: Move away from /dev/cpu/*/msr
On Wed, Jun 15, 2016 at 12:36:22PM +0200, Borislav Petkov wrote:
> Ah, yes, good point. Will change.

Ok, got a bit more involved - I also need to disable preemption around
smp_call_function_single(). Here's what I have now. It seems to work
too.

static ssize_t
energy_policy_pref_hint_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
u64 epb;

preempt_disable();
if (rdmsrl_on_cpu(dev->id, MSR_IA32_ENERGY_PERF_BIAS, &epb))
epb = -1;
preempt_enable();

return sprintf(buf, "%d\n", (unsigned int)(epb & 0xFULL));
}

static ssize_t
energy_policy_pref_hint_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
u32 val;
u64 epb;

if (kstrtou32(buf, 10, &val) < 0)
return -EINVAL;

if (val > 15)
return -EINVAL;

preempt_disable();

if (rdmsrl_on_cpu(dev->id, MSR_IA32_ENERGY_PERF_BIAS, &epb)) {
count = -EINVAL;
goto out;
}

if ((epb & 0xf) == val)
goto out;

if (wrmsrl_on_cpu(dev->id, MSR_IA32_ENERGY_PERF_BIAS, (epb & ~0xFULL) | val))
count = -EINVAL;

out:
preempt_enable();
return count;
}

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.

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