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Avoid reading it multiple times in the entry or exit paths. A small number of cycles delay to timers is tolerable. Reviewed-by: Fabiano Rosas Signed-off-by: Nicholas Piggin --- arch/powerpc/kvm/book3s_hv.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 5c4ccebce682..f4e5a64457e6 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3557,12 +3557,13 @@ static int kvmhv_load_hv_regs_and_go(struct kvm_vcpu *vcpu, u64 time_limit, host_dawrx1 = mfspr(SPRN_DAWRX1); } - hdec = time_limit - mftb(); + tb = mftb(); + hdec = time_limit - tb; if (hdec < 0) return BOOK3S_INTERRUPT_HV_DECREMENTER; if (vc->tb_offset) { - u64 new_tb = mftb() + vc->tb_offset; + u64 new_tb = tb + vc->tb_offset; mtspr(SPRN_TBU40, new_tb); tb = mftb(); if ((tb & 0xffffff) < (new_tb & 0xffffff)) @@ -3760,7 +3761,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, if (!(vcpu->arch.ctrl & 1)) mtspr(SPRN_CTRLT, mfspr(SPRN_CTRLF) & ~1); - mtspr(SPRN_DEC, vcpu->arch.dec_expires - mftb()); + mtspr(SPRN_DEC, vcpu->arch.dec_expires - tb); if (kvmhv_on_pseries()) { /* @@ -3895,7 +3896,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vc->in_guest = 0; next_timer = timer_get_next_tb(); - mtspr(SPRN_DEC, next_timer - mftb()); + mtspr(SPRN_DEC, next_timer - tb); mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso); kvmhv_load_host_pmu(); -- 2.23.0