From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
kvm@vger.kernel.org, Wanpeng Li <wanpengli@tencent.com>,
Thomas Gleixner <tglx@linutronix.de>,
Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
Jim Mattson <jmattson@google.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v3 01/12] Revert "KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock"
Date: Tue, 3 Aug 2021 19:29:50 +0200 [thread overview]
Message-ID: <15a05059-beae-904b-645e-17faf760c261@redhat.com> (raw)
In-Reply-To: <YQlch2fVEfDnz8aX@google.com>
On 03/08/21 17:11, Sean Christopherson wrote:
>> On top of this, I think the CD case (kvm_post_set_cr0) can be changed to use
>> kvm_mmu_zap_all_fast.
> No, because fast zap requires kvm->slots_lock be held.
Yeah, that much I knew. :) The issue is the usual ordering between
slots_lock and SRCU.
Paolo
That could be relaxed by
> reverting ca333add6933 ("KVM: x86/mmu: Explicitly track only a single invalid mmu
> generation") and converting mmu_valid_gen to a u64 (to prevent wrap on 32-bit KVM).
> IMO the extra memory cost, even though it's meager savings when using TDP without
> nested, isn't worth relaxing the rules for fast zap. Non-coherent DMA isn't very
> common these days, and toggling CR0.CD is a rare guest operation (it'd probably
> never happen if the darn architcture didn't set it on RESET).
>
next prev parent reply other threads:[~2021-08-03 17:29 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-02 18:33 [PATCH v3 00/12] My AVIC patch queue Maxim Levitsky
2021-08-02 18:33 ` [PATCH v3 01/12] Revert "KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock" Maxim Levitsky
2021-08-03 8:05 ` Paolo Bonzini
2021-08-03 15:11 ` Sean Christopherson
2021-08-03 17:29 ` Paolo Bonzini [this message]
2021-08-02 18:33 ` [PATCH v3 02/12] KVM: x86/mmu: bump mmu notifier count in kvm_zap_gfn_range Maxim Levitsky
2021-08-03 9:00 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 03/12] KVM: x86/mmu: rename try_async_pf to kvm_faultin_pfn Maxim Levitsky
2021-08-03 9:00 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 04/12] KVM: x86/mmu: allow kvm_faultin_pfn to return page fault handling code Maxim Levitsky
2021-08-03 9:00 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 05/12] KVM: x86/mmu: allow APICv memslot to be partially enabled Maxim Levitsky
2021-08-03 9:12 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 06/12] KVM: x86: don't disable APICv memslot when inhibited Maxim Levitsky
2021-08-03 8:44 ` Paolo Bonzini
2021-08-09 18:51 ` Maxim Levitsky
2021-08-09 19:14 ` Sean Christopherson
2021-08-02 18:33 ` [PATCH v3 07/12] KVM: x86: APICv: fix race in kvm_request_apicv_update on SVM Maxim Levitsky
2021-08-02 18:33 ` [PATCH v3 08/12] KVM: SVM: add warning for mistmatch between AVIC state and AVIC access page state Maxim Levitsky
2021-08-03 8:45 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 09/12] KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use Maxim Levitsky
2021-08-03 8:47 ` Paolo Bonzini
2021-08-03 9:01 ` Paolo Bonzini
2021-08-03 9:11 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 10/12] KVM: SVM: remove svm_toggle_avic_for_irq_window Maxim Levitsky
2021-08-03 9:11 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 11/12] KVM: SVM: call avic_vcpu_load/avic_vcpu_put when enabling/disabling AVIC Maxim Levitsky
2021-08-03 9:00 ` Paolo Bonzini
2021-08-02 18:33 ` [PATCH v3 12/12] KVM: SVM: AVIC: drop unsupported AVIC base relocation code Maxim Levitsky
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