On 9/21/2015 9:36 AM, Linus Torvalds wrote:
On Mon, Sep 21, 2015 at 1:46 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
Linus, what's your preference?
So quite frankly, is there any reason we don't just implement
native_read_msr() as just
unsigned long long native_read_msr(unsigned int msr)
{
int err;
unsigned long long val;
val = native_read_msr_safe(msr, &err);
WARN_ON_ONCE(err);
return val;
}
Note: no inline, no nothing. Just put it in arch/x86/lib/msr.c, and be
done with it. I don't see the downside.
How many msr reads are <i>so</i> critical that the function call
overhead would matter?
if anything qualifies it'd be switch_to() and friends.
note that I'm not entirely happy about the notion of "safe" MSRs.
They're safe as in "won't fault".
Reading random MSRs isn't a generic safe operation though, but the name sort of gives people
the impression that it is. Even with _safe variants, you still need to KNOW the MSR exists (by means
of CPUID or similar) unfortunately.
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