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From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>, kvm@vger.kernel.org
Cc: Wanpeng Li <wanpengli@tencent.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>,
	Sean Christopherson <seanjc@google.com>,
	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 06/12] KVM: x86: don't disable APICv memslot when inhibited
Date: Tue, 3 Aug 2021 10:44:09 +0200	[thread overview]
Message-ID: <f221e94c-fb64-a859-de3c-30f883eac657@redhat.com> (raw)
In-Reply-To: <20210802183329.2309921-7-mlevitsk@redhat.com>

Reviewing this patch and the next one together.

On 02/08/21 20:33, Maxim Levitsky wrote:
> +static int avic_alloc_access_page(struct kvm *kvm)
>  {
>  	void __user *ret;
>  	int r = 0;
>  
>  	mutex_lock(&kvm->slots_lock);
> +
> +	if (kvm->arch.apic_access_memslot_enabled)
>  		goto out;

This variable is overloaded between "is access enabled" and "is the 
memslot allocated".  I think you should check 
kvm->arch.apicv_inhibit_reasons instead in kvm_faultin_pfn.


> +	if (!activate)
> +		kvm_zap_gfn_range(kvm, gpa_to_gfn(APIC_DEFAULT_PHYS_BASE),
> +				  gpa_to_gfn(APIC_DEFAULT_PHYS_BASE + PAGE_SIZE));
> +

Off by one, the last argument of kvm_zap_gfn_range is inclusive:
Also, checking "activate" is a bit ugly when we have "new" available as 
well.  Yes, they are the same if !!old != !!new, but we care about the 
global state, not the single bit.

Putting everything together, this could become something like

         trace_kvm_apicv_update_request(activate, bit);
         if (!!old != !!new) {
		/*
		 * Kick all CPUs out of guest mode.  When
		 * kvm_vcpu_update_apicv succeeds in taking
		 * apicv_update_lock, it will see the
		 * new apicv_inhibit_reasons that we set below.
		 */
	        kvm_make_all_cpus_request(kvm, KVM_REQ_APICV_UPDATE);

	        if (new) {
	                unsigned long gfn = gpa_to_gfn(APIC_DEFAULT_PHYS_BASE);
	                kvm_zap_gfn_range(kvm, gfn, gfn);
	        }
	}
         kvm->arch.apicv_inhibit_reasons = new;
         mutex_unlock(&kvm->arch.apicv_update_lock);

Paolo


  reply	other threads:[~2021-08-03  8:44 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
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 [this message]
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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