From: Nicholas Piggin <npiggin@gmail.com>
To: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v3 23/41] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit
Date: Sat, 6 Mar 2021 01:06:20 +1000 [thread overview]
Message-ID: <20210305150638.2675513-24-npiggin@gmail.com> (raw)
In-Reply-To: <20210305150638.2675513-1-npiggin@gmail.com>
mftb is serialising (dispatch next-to-complete) so it is heavy weight
for a mfspr. Avoid reading it multiple times in the entry or exit paths.
A small number of cycles delay to timers is tolerable.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
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 c1965a9d8d00..6f3e3aed99aa 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3505,12 +3505,13 @@ 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))
@@ -3703,7 +3704,7 @@ 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()) {
/*
@@ -3837,7 +3838,7 @@ 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());
+ mtspr(SPRN_DEC, local_paca->kvm_hstate.dec_expires - tb);
mtspr(SPRN_SPRG_VDSO_WRITE, local_paca->sprg_vdso);
kvmhv_load_host_pmu();
--
2.23.0
next prev parent reply other threads:[~2021-03-05 15:16 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 15:05 [PATCH v3 00/41] KVM: PPC: Book3S: C-ify the P9 entry/exit code Nicholas Piggin
2021-03-05 15:05 ` [PATCH v3 01/41] KVM: PPC: Book3S HV: Disallow LPCR[AIL] to be set to 1 or 2 Nicholas Piggin
2021-03-08 15:26 ` Fabiano Rosas
2021-03-09 1:11 ` Nicholas Piggin
2021-03-05 15:05 ` [PATCH v3 02/41] KVM: PPC: Book3S HV: Prevent radix guests from setting LPCR[TC] Nicholas Piggin
2021-03-08 15:47 ` Fabiano Rosas
2021-03-09 1:14 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 03/41] KVM: PPC: Book3S HV: Remove redundant mtspr PSPB Nicholas Piggin
2021-03-12 5:07 ` Daniel Axtens
2021-03-05 15:06 ` [PATCH v3 04/41] KVM: PPC: Book3S HV: remove unused kvmppc_h_protect argument Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 05/41] KVM: PPC: Book3S HV: Fix CONFIG_SPAPR_TCE_IOMMU=n default hcalls Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 06/41] powerpc/64s: Remove KVM handler support from CBE_RAS interrupts Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 07/41] powerpc/64s: remove KVM SKIP test from instruction breakpoint handler Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 08/41] KVM: PPC: Book3S HV: Ensure MSR[ME] is always set in guest MSR Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 09/41] KVM: PPC: Book3S 64: move KVM interrupt entry to a common entry point Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 10/41] KVM: PPC: Book3S 64: Move GUEST_MODE_SKIP test into KVM Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 11/41] KVM: PPC: Book3S 64: add hcall interrupt handler Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 12/41] KVM: PPC: Book3S 64: Move hcall early register setup to KVM Nicholas Piggin
2021-03-12 5:45 ` Daniel Axtens
2021-03-16 3:43 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 13/41] KVM: PPC: Book3S 64: Move interrupt " Nicholas Piggin
2021-03-20 7:19 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 14/41] KVM: PPC: Book3S 64: move bad_host_intr check to HV handler Nicholas Piggin
2021-03-20 9:07 ` Alexey Kardashevskiy
2021-03-22 3:18 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 15/41] KVM: PPC: Book3S 64: Minimise hcall handler calling convention differences Nicholas Piggin
2021-03-22 2:09 ` Alexey Kardashevskiy
2021-03-22 4:06 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 16/41] KVM: PPC: Book3S HV P9: Move radix MMU switching instructions together Nicholas Piggin
2021-03-22 4:24 ` Alexey Kardashevskiy
2021-03-22 5:25 ` Nicholas Piggin
2021-03-22 6:21 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 17/41] KVM: PPC: Book3S HV P9: implement kvmppc_xive_pull_vcpu in C Nicholas Piggin
2021-03-22 5:05 ` Alexey Kardashevskiy
2021-03-22 16:19 ` Cédric Le Goater
2021-03-22 18:13 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 18/41] KVM: PPC: Book3S HV P9: Move xive vcpu context management into kvmhv_p9_guest_entry Nicholas Piggin
2021-03-22 5:30 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 19/41] KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9 path Nicholas Piggin
2021-03-17 16:22 ` Fabiano Rosas
2021-03-17 22:41 ` Nicholas Piggin
2021-03-22 16:12 ` Cédric Le Goater
2021-03-22 7:30 ` Alexey Kardashevskiy
2021-03-22 13:15 ` Nicholas Piggin
2021-03-22 16:01 ` Cédric Le Goater
2021-03-22 18:22 ` Nicholas Piggin
2021-03-23 7:26 ` Cédric Le Goater
2021-03-05 15:06 ` [PATCH v3 20/41] KVM: PPC: Book3S HV P9: Move setting HDEC after switching to guest LPCR Nicholas Piggin
2021-03-08 17:52 ` Fabiano Rosas
2021-03-22 8:39 ` Alexey Kardashevskiy
2021-03-22 13:24 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 21/41] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC Nicholas Piggin
2021-03-22 7:58 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 22/41] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read Nicholas Piggin
2021-03-05 15:06 ` Nicholas Piggin [this message]
2021-03-12 12:55 ` [PATCH v3 23/41] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit Fabiano Rosas
2021-03-05 15:06 ` [PATCH v3 24/41] powerpc: add set_dec_or_work API for safely updating decrementer Nicholas Piggin
2021-03-22 9:38 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 25/41] KVM: PPC: Book3S HV P9: Reduce irq_work vs guest decrementer races Nicholas Piggin
2021-03-23 1:43 ` Alexey Kardashevskiy
2021-03-05 15:06 ` [PATCH v3 26/41] KVM: PPC: Book3S HV P9: Implement the rest of the P9 path in C Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 27/41] KVM: PPC: Book3S HV P9: inline kvmhv_load_hv_regs_and_go into __kvmhv_vcpu_entry_p9 Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 28/41] KVM: PPC: Book3S HV P9: Read machine check registers while MSR[RI] is 0 Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 29/41] KVM: PPC: Book3S HV P9: Improve exit timing accounting coverage Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 30/41] KVM: PPC: Book3S HV P9: Move SPR loading after expiry time check Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 31/41] KVM: PPC: Book3S HV P9: Add helpers for OS SPR handling Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 32/41] KVM: PPC: Book3S HV P9: Switch to guest MMU context as late as possible Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 33/41] KVM: PPC: Book3S HV: Implement radix prefetch workaround by disabling MMU Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 34/41] KVM: PPC: Book3S HV: Remove support for dependent threads mode on P9 Nicholas Piggin
2021-03-17 15:11 ` Aneesh Kumar K.V
2021-03-22 3:27 ` Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 35/41] KVM: PPC: Book3S HV: Remove radix guest support from P7/8 path Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 36/41] KVM: PPC: Book3S HV P9: Allow all P9 processors to enable nested HV Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 37/41] KVM: PPC: Book3S HV: small pseries_do_hcall cleanup Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 38/41] KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page faults Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 39/41] KVM: PPC: Book3S HV P9: implement hash guest support Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 40/41] KVM: PPC: Book3S HV P9: implement hash host / " Nicholas Piggin
2021-03-05 15:06 ` [PATCH v3 41/41] KVM: PPC: Book3S HV: remove ISA v3.0 and v3.1 support from P7/8 path Nicholas Piggin
2021-03-16 6:06 ` [PATCH v3 00/41] KVM: PPC: Book3S: C-ify the P9 entry/exit code Nicholas Piggin
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