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KVM: PPC: Use exported tb_to_ns() function in decrementer emulation

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This changes the KVM code that emulates the decrementer function to do
the conversion of decrementer values to time intervals in nanoseconds
by calling the tb_to_ns() function exported by the powerpc timer code,
in preference to open-coded arithmetic using values from the
decrementer_clockevent struct.  Similarly, the HV-KVM code that did
the same conversion using arithmetic on tb_ticks_per_sec also now
uses tb_to_ns().

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Paul Mackerras 2018-10-20 20:54:55 +11:00 committed by Michael Ellerman
parent 772b039fd9
commit c43befca86
2 changed files with 4 additions and 6 deletions
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3
arch/powerpc/kvm/book3s_hv.c
View File

@ -2160,8 +2160,7 @@ static void kvmppc_set_timer(struct kvm_vcpu *vcpu)
kvmppc_core_prepare_to_enter(vcpu);
return;
}
dec_nsec = (vcpu->arch.dec_expires - now) * NSEC_PER_SEC
/ tb_ticks_per_sec;
dec_nsec = tb_to_ns(vcpu->arch.dec_expires - now);
hrtimer_start(&vcpu->arch.dec_timer, dec_nsec, HRTIMER_MODE_REL);
vcpu->arch.timer_running = 1;
}

7
arch/powerpc/kvm/emulate.c
View File

@ -61,11 +61,10 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
dec_time = vcpu->arch.dec;
/*
* Guest timebase ticks at the same frequency as host decrementer.
* So use the host decrementer calculations for decrementer emulation.
* Guest timebase ticks at the same frequency as host timebase.
* So use the host timebase calculations for decrementer emulation.
*/
dec_time = dec_time << decrementer_clockevent.shift;
do_div(dec_time, decrementer_clockevent.mult);
dec_time = tb_to_ns(dec_time);
dec_nsec = do_div(dec_time, NSEC_PER_SEC);
hrtimer_start(&vcpu->arch.dec_timer,
ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);