From: David Matlack <dmatlack@google.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
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>,
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,
linux-kernel@vger.kernel.org, Jing Zhang <jingzhangos@google.com>
Subject: Re: [PATCH 13/14] KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs
Date: Tue, 28 Sep 2021 22:12:50 +0000 [thread overview]
Message-ID: <YVOTYk9aSl72hCmX@google.com> (raw)
In-Reply-To: <20210925005528.1145584-14-seanjc@google.com>
On Fri, Sep 24, 2021 at 05:55:27PM -0700, Sean Christopherson wrote:
> Go directly to kvm_vcpu_block() when handling the case where userspace
> attempts to run an UNINITIALIZED vCPU. The vCPU isn't halted and its time
> spent in limbo arguably should not be factored into halt-polling as the
> behavior of the VM at this point is not at all indicative of the behavior
> of the VM once it is up and running, i.e. executing HLT in idle tasks.
>
> Note, because this case is encountered only on the first run of an AP vCPU,
> vcpu->halt_poll_ns is guaranteed to be '0', and so KVM will not attempt
> halt-polling, i.e. this really only affects the post-block bookkeeping.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
> ---
> arch/x86/kvm/x86.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0d71c73a61bb..b444f9315766 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10127,7 +10127,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
> r = -EINTR;
> goto out;
> }
> - kvm_vcpu_halt(vcpu);
> + kvm_vcpu_block(vcpu);
> if (kvm_apic_accept_events(vcpu) < 0) {
> r = 0;
> goto out;
> --
> 2.33.0.685.g46640cef36-goog
>
next prev parent reply other threads:[~2021-09-28 22:12 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-25 0:55 [PATCH 00/14] KVM: Halt-polling fixes, cleanups and a new stat Sean Christopherson
2021-09-25 0:55 ` [PATCH 01/14] KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU Sean Christopherson
2021-09-27 6:54 ` Christian Borntraeger
2021-09-25 0:55 ` [PATCH 02/14] KVM: Update halt-polling stats if and only if halt-polling was attempted Sean Christopherson
2021-09-28 18:57 ` David Matlack
2021-09-25 0:55 ` [PATCH 03/14] KVM: Refactor and document halt-polling stats update helper Sean Christopherson
2021-09-28 19:01 ` David Matlack
2021-09-25 0:55 ` [PATCH 04/14] KVM: Reconcile discrepancies in halt-polling stats Sean Christopherson
2021-09-28 21:26 ` David Matlack
2021-09-25 0:55 ` [PATCH 05/14] KVM: s390: Clear valid_wakeup in kvm_s390_handle_wait(), not in arch hook Sean Christopherson
2021-09-27 6:58 ` Christian Borntraeger
2021-09-25 0:55 ` [PATCH 06/14] KVM: Drop obsolete kvm_arch_vcpu_block_finish() Sean Christopherson
2021-09-27 6:58 ` Christian Borntraeger
2021-09-28 21:28 ` David Matlack
2021-09-25 0:55 ` [PATCH 07/14] KVM: Don't block+unblock when halt-polling is successful Sean Christopherson
2021-09-25 9:50 ` Marc Zyngier
2021-09-26 6:27 ` Paolo Bonzini
2021-09-26 9:02 ` Marc Zyngier
2021-09-27 17:28 ` Sean Christopherson
2021-09-28 9:24 ` Marc Zyngier
2021-09-28 16:21 ` Sean Christopherson
2021-09-30 9:36 ` Marc Zyngier
2021-09-25 0:55 ` [PATCH 08/14] KVM: x86: Tweak halt emulation helper names to free up kvm_vcpu_halt() Sean Christopherson
2021-09-28 21:59 ` David Matlack
2021-09-25 0:55 ` [PATCH 09/14] KVM: Rename kvm_vcpu_block() => kvm_vcpu_halt() Sean Christopherson
2021-09-27 7:06 ` Christian Borntraeger
2021-09-28 22:01 ` David Matlack
2021-09-25 0:55 ` [PATCH 10/14] KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() Sean Christopherson
2021-09-27 7:41 ` Christian Borntraeger
2021-09-28 22:03 ` David Matlack
2021-09-25 0:55 ` [PATCH 11/14] KVM: stats: Add stat to detect if vcpu is currently blocking Sean Christopherson
2021-09-28 22:04 ` David Matlack
2021-09-25 0:55 ` [PATCH 12/14] KVM: Don't redo ktime_get() when calculating halt-polling stop/deadline Sean Christopherson
2021-09-28 22:08 ` David Matlack
2021-09-25 0:55 ` [PATCH 13/14] KVM: x86: Directly block (instead of "halting") UNINITIALIZED vCPUs Sean Christopherson
2021-09-28 22:12 ` David Matlack [this message]
2021-09-25 0:55 ` [PATCH 14/14] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states Sean Christopherson
2021-09-28 22:14 ` David Matlack
2021-09-27 7:22 ` disabling halt polling broken? (was Re: [PATCH 00/14] KVM: Halt-polling fixes, cleanups and a new stat) Christian Borntraeger
2021-09-27 14:59 ` Sean Christopherson
2021-09-27 15:03 ` Paolo Bonzini
2021-09-27 15:15 ` Sean Christopherson
2021-09-27 15:16 ` Christian Borntraeger
2021-09-27 16:58 ` David Matlack
2021-09-29 6:56 ` Christian Borntraeger
2021-09-27 17:24 ` Paolo Bonzini
2021-09-27 17:33 ` Sean Christopherson
2022-11-15 3:28 ` wangyanan (Y)
2022-11-16 17:19 ` David Matlack
2022-11-18 2:29 ` wangyanan (Y)
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