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From: Nicholas Piggin <npiggin@gmail.com>
To: kvm-ppc@vger.kernel.org
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>,
	linuxppc-dev@lists.ozlabs.org,
	Nicholas Piggin <npiggin@gmail.com>
Subject: [RFC PATCH 02/43] KMV: PPC: Book3S HV P9: Use set_dec to set decrementer to host
Date: Tue, 22 Jun 2021 20:56:55 +1000	[thread overview]
Message-ID: <20210622105736.633352-3-npiggin@gmail.com> (raw)
In-Reply-To: <20210622105736.633352-1-npiggin@gmail.com>

The host Linux timer code arms the decrementer with the value
'decrementers_next_tb - current_tb' using set_dec(), which stores
val - 1 on Book3S-64, which is not quite the same as what KVM does
to re-arm the host decrementer when exiting the guest.

This shouldn't be a significant change, but it makes the logic match
and avoids this small extra change being brought into the next patch.

Suggested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kvm/book3s_hv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 97f3d6d54b61..d19b4ae01642 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3914,7 +3914,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit,
 	vc->entry_exit_map = 0x101;
 	vc->in_guest = 0;
 
-	mtspr(SPRN_DEC, local_paca->kvm_hstate.dec_expires - mftb());
+	set_dec(local_paca->kvm_hstate.dec_expires - mftb());
 	/* We may have raced with new irq work */
 	if (test_irq_work_pending())
 		set_dec(1);
-- 
2.23.0


  parent reply	other threads:[~2021-06-22 10:59 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-22 10:56 [RFC PATCH 00/43] KVM: PPC: Book3S HV P9: entry/exit optimisations round 1 Nicholas Piggin
2021-06-22 10:56 ` [RFC PATCH 01/43] powerpc/64s: Remove WORT SPR from POWER9/10 Nicholas Piggin
2021-06-30 17:29   ` Fabiano Rosas
2021-06-22 10:56 ` Nicholas Piggin [this message]
2021-06-22 10:56 ` [RFC PATCH 03/43] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read Nicholas Piggin
2021-06-22 10:56 ` [RFC PATCH 04/43] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Nicholas Piggin
2021-06-22 10:56 ` [RFC PATCH 05/43] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Nicholas Piggin
2021-06-22 10:56 ` [RFC PATCH 06/43] powerpc/time: add API for KVM to re-arm the host timer/decrementer Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 07/43] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests Nicholas Piggin
2021-06-30 19:41   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 08/43] powerpc/64s: Keep AMOR SPR a constant ~0 at runtime Nicholas Piggin
2021-06-30 19:17   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 09/43] KVM: PPC: Book3S HV: Don't always save PMU for guest capable of nesting Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 10/43] powerpc/64s: Always set PMU control registers to frozen/disabled when not in use Nicholas Piggin
2021-07-01 13:17   ` Madhavan Srinivasan
2021-07-02  0:27     ` Nicholas Piggin
2021-07-08 12:45       ` Nicholas Piggin
2021-07-12  3:42       ` Madhavan Srinivasan
2021-07-10  2:50   ` Athira Rajeev
2021-07-12  2:41     ` Nicholas Piggin
2021-07-12  3:17       ` Athira Rajeev
2021-07-14 12:39       ` Nicholas Piggin
2021-07-16  3:43         ` Madhavan Srinivasan
2021-06-22 10:57 ` [RFC PATCH 11/43] KVM: PPC: Book3S HV P9: Implement PMU save/restore in C Nicholas Piggin
2021-07-10  2:47   ` Athira Rajeev
2021-07-12  2:49     ` Nicholas Piggin
2021-07-12 14:07       ` Athira Rajeev
2021-06-22 10:57 ` [RFC PATCH 12/43] KVM: PPC: Book3S HV P9: Factor out yield_count increment Nicholas Piggin
2021-07-08 17:56   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 13/43] KVM: PPC: Book3S HV P9: Factor PMU save/load into context switch functions Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 14/43] KVM: PPC: Book3S HV P9: Demand fault PMU SPRs when marked not inuse Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 15/43] KVM: PPC: Book3S HV: CTRL SPR does not require read-modify-write Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 16/43] KVM: PPC: Book3S HV P9: Move SPRG restore to restore_p9_host_os_sprs Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 17/43] KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 18/43] KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 19/43] KVM: PPC: Book3S HV P9: Add kvmppc_stop_thread to match kvmppc_start_thread Nicholas Piggin
2021-06-30 20:18   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 20/43] KVM: PPC: Book3S HV: Change dec_expires to be relative to guest timebase Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 21/43] KVM: PPC: Book3S HV P9: Move TB updates Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 22/43] KVM: PPC: Book3S HV P9: Optimise timebase reads Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 23/43] KVM: PPC: Book3S HV P9: Avoid SPR scoreboard stalls Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 24/43] KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 25/43] KVM: PPC: Book3S HV P9: Juggle SPR switching around Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 26/43] KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 27/43] KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in Nicholas Piggin
2021-07-08  5:32   ` Athira Rajeev
2021-07-12  2:50     ` Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 28/43] KVM: PPC: Book3S HV P9: Move nested guest entry into its own function Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 29/43] KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 30/43] KVM: PPC: Book3S HV P9: Implement TM fastpath for guest entry/exit Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 31/43] KVM: PPC: Book3S HV P9: Switch PMU to guest as late as possible Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 32/43] KVM: PPC: Book3S HV P9: Restrict DSISR canary workaround to processors that require it Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 33/43] KVM: PPC: Book3S HV P9: More SPR speed improvements Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 34/43] KVM: PPC: Book3S HV P9: Demand fault EBB facility registers Nicholas Piggin
2021-07-08 17:46   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 35/43] KVM: PPC: Book3S HV P9: Demand fault TM " Nicholas Piggin
2021-07-08 17:46   ` Fabiano Rosas
2021-06-22 10:57 ` [RFC PATCH 36/43] KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 37/43] KVM: PPC: Book3S HV P9: Comment and fix MMU context switching code Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 38/43] KVM: PPC: Book3S HV P9: Test dawr_enabled() before saving host DAWR SPRs Nicholas Piggin
2021-06-30 17:51   ` Fabiano Rosas
2021-07-01  8:04     ` Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 39/43] KVM: PPC: Book3S HV P9: Don't restore PSSCR if not needed Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 40/43] KVM: PPC: Book3S HV P9: Avoid tlbsync sequence on radix guest exit Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 41/43] KVM: PPC: Book3S HV Nested: Avoid extra mftb() in nested entry Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 42/43] KVM: PPC: Book3S HV P9: Improve mfmsr performance on entry Nicholas Piggin
2021-06-22 10:57 ` [RFC PATCH 43/43] KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving Nicholas Piggin

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