From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>, kvm@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Jim Mattson <jmattson@google.com>
Subject: Re: [PATCH 02/10] KVM: x86: APICv: fix race in kvm_request_apicv_update on SVM
Date: Wed, 23 Jun 2021 23:50:35 +0200 [thread overview]
Message-ID: <6c4a69ce-595e-d5a1-7b4e-e6ce1afe1252@redhat.com> (raw)
In-Reply-To: <20210623113002.111448-3-mlevitsk@redhat.com>
On 23/06/21 13:29, Maxim Levitsky wrote:
> + kvm_block_guest_entries(kvm);
> +
> trace_kvm_apicv_update_request(activate, bit);
> if (kvm_x86_ops.pre_update_apicv_exec_ctrl)
> static_call(kvm_x86_pre_update_apicv_exec_ctrl)(kvm, activate);
> @@ -9243,6 +9245,8 @@ void kvm_request_apicv_update(struct kvm *kvm, bool activate, ulong bit)
> except = kvm_get_running_vcpu();
> kvm_make_all_cpus_request_except(kvm, KVM_REQ_APICV_UPDATE,
> except);
> +
> + kvm_allow_guest_entries(kvm);
Doesn't this cause a busy loop during synchronize_rcu? It should be
possible to request the vmexit of other CPUs from
avic_update_access_page, and do a lock/unlock of kvm->slots_lock to wait
for the memslot to be updated.
(As an aside, I'd like to get rid of KVM_REQ_MCLOCK_IN_PROGRESS in 5.15...).
Paolo
next prev parent reply other threads:[~2021-06-23 21:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-23 11:29 [PATCH 00/10] My AVIC patch queue Maxim Levitsky
2021-06-23 11:29 ` [PATCH 01/10] KVM: x86: extract block/allow guest enteries Maxim Levitsky
2021-06-23 11:29 ` [PATCH 02/10] KVM: x86: APICv: fix race in kvm_request_apicv_update on SVM Maxim Levitsky
2021-06-23 21:50 ` Paolo Bonzini [this message]
2021-06-24 8:07 ` Maxim Levitsky
2021-07-07 12:57 ` Maxim Levitsky
2021-07-07 13:58 ` Paolo Bonzini
2021-06-23 11:29 ` [PATCH 03/10] KVM: x86: rename apic_access_page_done to apic_access_memslot_enabled Maxim Levitsky
2021-06-23 21:50 ` Paolo Bonzini
2021-06-23 11:29 ` [PATCH 04/10] KVM: SVM: add warning for mistmatch between AVIC state and AVIC access page state Maxim Levitsky
2021-06-23 21:53 ` Paolo Bonzini
2021-06-24 8:13 ` Maxim Levitsky
2021-06-23 11:29 ` [PATCH 05/10] KVM: SVM: svm_set_vintr don't warn if AVIC is active but is about to be deactivated Maxim Levitsky
2021-06-23 11:29 ` [PATCH 06/10] KVM: SVM: tweak warning about enabled AVIC on nested entry Maxim Levitsky
2021-06-23 21:52 ` Paolo Bonzini
2021-06-23 11:29 ` [PATCH 07/10] KVM: SVM: use vmcb01 in svm_refresh_apicv_exec_ctrl Maxim Levitsky
2021-06-23 21:54 ` Paolo Bonzini
2021-06-24 8:16 ` Maxim Levitsky
2021-06-23 11:30 ` [PATCH 08/10] KVM: x86: APICv: drop immediate APICv disablement on current vCPU Maxim Levitsky
2021-06-23 11:30 ` [PATCH 09/10] KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC Maxim Levitsky
2021-06-23 11:30 ` [PATCH 10/10] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Maxim Levitsky
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