KVM: PPC: Use exported tb_to_ns() function in decrementer emulation (c43befca) · Commits · 戴 / test

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>

arch/powerpc/kvm/book3s_hv.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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;
		}

arch/powerpc/kvm/emulate.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -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);

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