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From: Sean Christopherson <seanjc@google.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Marc Zyngier <maz@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
	Paul Mackerras <paulus@ozlabs.org>,
	Anup Patel <anup.patel@wdc.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Janosch Frank <frankja@linux.ibm.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Atish Patra <atish.patra@wdc.com>,
	David Hildenbrand <david@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
	kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
	kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, David Matlack <dmatlack@google.com>,
	Oliver Upton <oupton@google.com>,
	Jing Zhang <jingzhangos@google.com>
Subject: Re: [PATCH v2 00/43] KVM: Halt-polling and x86 APICv overhaul
Date: Tue, 26 Oct 2021 14:48:02 +0000	[thread overview]
Message-ID: <YXgVIvYhABnrP2Jo@google.com> (raw)
In-Reply-To: <04b1a72e-47b4-4bde-eb9e-ba36c156ff0d@de.ibm.com>

On Tue, Oct 26, 2021, Christian Borntraeger wrote:
> Am 09.10.21 um 04:11 schrieb Sean Christopherson:
> > This is basically two series smushed into one.  The first "half" aims
> > to differentiate between "halt" and a more generic "block", where "halt"
> > aligns with x86's HLT instruction, the halt-polling mechanisms, and
> > associated stats, and "block" means any guest action that causes the vCPU
> > to block/wait.
> > 
> > The second "half" overhauls x86's APIC virtualization code (Posted
> > Interrupts on Intel VMX, AVIC on AMD SVM) to do their updates in response
> > to vCPU (un)blocking in the vcpu_load/put() paths, keying off of the
> > vCPU's rcuwait status to determine when a blocking vCPU is being put and
> > reloaded.  This idea comes from arm64's kvm_timer_vcpu_put(), which I
> > stumbled across when diving into the history of arm64's (un)blocking hooks.
> > 
> > The x86 APICv overhaul allows for killing off several sets of hooks in
> > common KVM and in x86 KVM (to the vendor code).  Moving everything to
> > vcpu_put/load() also realizes nice cleanups, especially for the Posted
> > Interrupt code, which required some impressive mental gymnastics to
> > understand how vCPU task migration interacted with vCPU blocking.
> > 
> > Non-x86 folks, sorry for the noise.  I'm hoping the common parts can get
> > applied without much fuss so that future versions can be x86-only.
> > 
> > v2:
> >   - Collect reviews. [Christian, David]
> >   - Add patch to move arm64 WFI functionality out of hooks. [Marc]
> >   - Add RISC-V to the fun.
> >   - Add all the APICv fun.
> 
> Have we actually followed up on the regression regarding halt_poll_ns=0 no longer disabling
> polling for running systems?

No, I have that conversation flagged but haven't gotten back to it.  I still like
the idea of special casing halt_poll_ns=0 to override the capability.  I can send
a proper patch for that unless there's a different/better idea?

  reply	other threads:[~2021-10-26 14:48 UTC|newest]

Thread overview: 141+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-09  2:11 [PATCH v2 00/43] KVM: Halt-polling and x86 APICv overhaul Sean Christopherson
2021-10-09  2:11 ` [PATCH v2 01/43] KVM: VMX: Don't unblock vCPU w/ Posted IRQ if IRQs are disabled in guest Sean Christopherson
2021-10-09  2:11 ` [PATCH v2 02/43] KVM: SVM: Ensure target pCPU is read once when signalling AVIC doorbell Sean Christopherson
2021-10-25 13:21   ` Paolo Bonzini
2021-10-27  9:50   ` Maxim Levitsky
2021-10-09  2:11 ` [PATCH v2 03/43] KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU Sean Christopherson
2021-10-09  2:11 ` [PATCH v2 04/43] KVM: Force PPC to define its own rcuwait object Sean Christopherson
2021-10-09  2:11 ` [PATCH v2 05/43] KVM: Update halt-polling stats if and only if halt-polling was attempted Sean Christopherson
2021-10-27 10:18   ` Maxim Levitsky
2021-10-09  2:11 ` [PATCH v2 06/43] KVM: Refactor and document halt-polling stats update helper Sean Christopherson
2021-10-27 10:56   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 07/43] KVM: Reconcile discrepancies in halt-polling stats Sean Christopherson
2021-10-27 11:29   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 08/43] KVM: s390: Clear valid_wakeup in kvm_s390_handle_wait(), not in arch hook Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 09/43] KVM: Drop obsolete kvm_arch_vcpu_block_finish() Sean Christopherson
2021-10-22 15:02   ` Anup Patel
2021-10-09  2:12 ` [PATCH v2 10/43] KVM: arm64: Move vGIC v4 handling for WFI out arch callback hook Sean Christopherson
2021-10-25 13:31   ` Paolo Bonzini
2021-10-26 15:41     ` Marc Zyngier
2021-10-26 16:12       ` Paolo Bonzini
2021-11-30 11:39         ` Paolo Bonzini
2021-11-30 12:04           ` Marc Zyngier
2021-11-30 16:07             ` Paolo Bonzini
2021-10-09  2:12 ` [PATCH v2 11/43] KVM: Don't block+unblock when halt-polling is successful Sean Christopherson
2021-10-27 13:40   ` Maxim Levitsky
2021-11-28 22:16     ` Maxim Levitsky
2021-11-29 17:25       ` Sean Christopherson
2021-11-29 17:53         ` Paolo Bonzini
2021-11-29 18:55           ` Sean Christopherson
2021-11-29 19:18             ` Paolo Bonzini
2021-11-29 22:53               ` Maxim Levitsky
2021-12-02  0:20                 ` Maxim Levitsky
2021-12-02  2:00                   ` Sean Christopherson
2021-12-02 10:31                     ` Paolo Bonzini
2021-11-29 17:55         ` Paolo Bonzini
2021-11-29 22:55           ` Maxim Levitsky
2021-12-02 10:20         ` Maxim Levitsky
2021-12-02 10:47           ` Maxim Levitsky
2021-12-02 12:02         ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 12/43] KVM: x86: Tweak halt emulation helper names to free up kvm_vcpu_halt() Sean Christopherson
2021-10-27 14:10   ` Maxim Levitsky
2021-10-27 14:18     ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 13/43] KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt() Sean Christopherson
2021-10-22 15:04   ` Anup Patel
2021-10-09  2:12 ` [PATCH v2 14/43] KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 15/43] KVM: stats: Add stat to detect if vcpu is currently blocking Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 16/43] KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline Sean Christopherson
2021-10-25 14:26   ` Paolo Bonzini
2021-10-27 14:35     ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 17/43] KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs Sean Christopherson
2021-10-27 14:46   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 18/43] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states Sean Christopherson
2021-10-27 15:18   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 19/43] KVM: Add helpers to wake/query blocking vCPU Sean Christopherson
2021-10-25 14:06   ` Paolo Bonzini
2021-10-27 19:27   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 20/43] KVM: VMX: Skip Posted Interrupt updates if APICv is hard disabled Sean Christopherson
2021-10-25 13:48   ` Paolo Bonzini
2021-10-28  9:12   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 21/43] KVM: VMX: Clean up PI pre/post-block WARNs Sean Christopherson
2021-10-28 10:20   ` Maxim Levitsky
2021-10-28 15:34     ` Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 22/43] KVM: VMX: Drop unnecessary PI logic to handle impossible conditions Sean Christopherson
2021-10-25 13:53   ` Paolo Bonzini
2021-10-28 14:36   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 23/43] KVM: VMX: Use boolean returns for Posted Interrupt "test" helpers Sean Christopherson
2021-10-28  6:05   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 24/43] KVM: VMX: Drop pointless PI.NDST update when blocking Sean Christopherson
2021-10-25 14:01   ` Paolo Bonzini
2021-10-27 14:26     ` Sean Christopherson
2021-10-28 10:53   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 25/43] KVM: VMX: Save/restore IRQs (instead of CLI/STI) during PI pre/post block Sean Christopherson
2021-10-28 10:54   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 26/43] KVM: VMX: Read Posted Interrupt "control" exactly once per loop iteration Sean Christopherson
2021-10-28 10:58   ` Maxim Levitsky
2021-10-28 15:55     ` Sean Christopherson
2021-10-31 22:48       ` Maxim Levitsky
2021-11-01 17:41         ` Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 27/43] KVM: VMX: Move Posted Interrupt ndst computation out of write loop Sean Christopherson
2021-10-28 11:28   ` Maxim Levitsky
2021-10-28 16:09     ` Maxim Levitsky
2021-10-28 16:12     ` Sean Christopherson
2021-10-31 22:51       ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 28/43] KVM: VMX: Remove vCPU from PI wakeup list before updating PID.NV Sean Christopherson
2021-10-28 12:53   ` Maxim Levitsky
2021-10-28 17:19     ` Sean Christopherson
2021-10-31 22:52       ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 29/43] KVM: VMX: Handle PI wakeup shenanigans during vcpu_put/load Sean Christopherson
2021-10-28 15:14   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 30/43] KVM: Drop unused kvm_vcpu.pre_pcpu field Sean Christopherson
2021-10-28 15:16   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 31/43] KVM: Move x86 VMX's posted interrupt list_head to vcpu_vmx Sean Christopherson
2021-10-28 15:33   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 32/43] KVM: VMX: Move preemption timer <=> hrtimer dance to common x86 Sean Christopherson
2021-10-28 15:45   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 33/43] KVM: x86: Unexport LAPIC's switch_to_{hv,sw}_timer() helpers Sean Christopherson
2021-10-28 15:45   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 34/43] KVM: x86: Remove defunct pre_block/post_block kvm_x86_ops hooks Sean Christopherson
2021-10-28 15:46   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 35/43] KVM: SVM: Signal AVIC doorbell iff vCPU is in guest mode Sean Christopherson
2021-10-25 14:26   ` Paolo Bonzini
2021-10-27 15:06     ` Sean Christopherson
2021-10-27 15:36       ` Paolo Bonzini
2021-10-27 16:08         ` Sean Christopherson
2021-10-27 16:14           ` Paolo Bonzini
2021-10-28 16:12   ` Maxim Levitsky
2021-10-28 17:06     ` Sean Christopherson
2021-10-09  2:12 ` [PATCH v2 36/43] KVM: SVM: Don't bother checking for "running" AVIC when kicking for IPIs Sean Christopherson
2021-10-31 14:50   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 37/43] KVM: SVM: Unconditionally mark AVIC as running on vCPU load (with APICv) Sean Christopherson
2021-10-25 14:22   ` Paolo Bonzini
2021-10-25 15:48     ` Sean Christopherson
2021-10-25 15:57       ` Paolo Bonzini
2021-10-25 16:00         ` Sean Christopherson
2021-10-31 16:34   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 38/43] KVM: Drop defunct kvm_arch_vcpu_(un)blocking() hooks Sean Christopherson
2021-10-31 16:35   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 39/43] KVM: VMX: Don't do full kick when triggering posted interrupt "fails" Sean Christopherson
2021-10-25 14:34   ` Paolo Bonzini
2021-10-27 16:04     ` Sean Christopherson
2021-10-27 22:09       ` Paolo Bonzini
2021-10-31 22:15         ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 40/43] KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this vCPU Sean Christopherson
2021-10-25 15:05   ` Paolo Bonzini
2021-10-27 15:30     ` Sean Christopherson
2021-10-31 22:19       ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 41/43] KVM: VMX: Pass desired vector instead of bool for triggering posted IRQ Sean Christopherson
2021-10-31 22:25   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 42/43] KVM: VMX: Fold fallback path into triggering posted IRQ helper Sean Christopherson
2021-10-31 22:30   ` Maxim Levitsky
2021-10-09  2:12 ` [PATCH v2 43/43] KVM: VMX: Don't do full kick when handling posted interrupt wakeup Sean Christopherson
2021-10-25 14:16   ` Paolo Bonzini
2021-10-31 22:33     ` Maxim Levitsky
2021-10-25 14:13 ` [PATCH v2 00/43] KVM: Halt-polling and x86 APICv overhaul Paolo Bonzini
2021-10-27 14:41   ` Sean Christopherson
2021-10-27 14:57     ` Paolo Bonzini
2021-10-27 15:28       ` Sean Christopherson
2021-10-27 15:37         ` Paolo Bonzini
2021-10-26  7:20 ` Christian Borntraeger
2021-10-26 14:48   ` Sean Christopherson [this message]
2021-10-26 18:29     ` Christian Borntraeger

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