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([2001:b07:6468:f312:1000:6128:564:d837]) by smtp.gmail.com with ESMTPSA id d7sm9923543wrn.78.2020.05.02.09.42.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 May 2020 09:42:04 -0700 (PDT) Subject: Re: AVIC related warning in enable_irq_window To: Maxim Levitsky , kvm@vger.kernel.org Cc: Suravee Suthikulpanit , linux-kernel@vger.kernel.org References: <9ce7bb5c4fb8bcc4ac21103f7534a6edfcbe195d.camel@redhat.com> From: Paolo Bonzini Message-ID: <758b27a8-74c0-087d-d90b-d95faee2f561@redhat.com> Date: Sat, 2 May 2020 18:42:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <9ce7bb5c4fb8bcc4ac21103f7534a6edfcbe195d.camel@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/05/20 15:58, Maxim Levitsky wrote: > The AVIC is disabled by svm_toggle_avic_for_irq_window, which calls > kvm_request_apicv_update, which broadcasts the KVM_REQ_APICV_UPDATE vcpu request, > however it doesn't broadcast it to CPU on which now we are running, which seems OK, > because the code that handles that broadcast runs on each VCPU entry, thus > when this CPU will enter guest mode it will notice and disable the AVIC. > > However later in svm_enable_vintr, there is test 'WARN_ON(kvm_vcpu_apicv_active(&svm->vcpu));' > which is still true on current CPU because of the above. Good point! We can just remove the WARN_ON I think. Can you send a patch? svm_set_vintr also has a rather silly static void svm_set_vintr(struct vcpu_svm *svm) { set_intercept(svm, INTERCEPT_VINTR); if (is_intercept(svm, INTERCEPT_VINTR)) svm_enable_vintr(svm); } so I'm thinking of just inlining svm_enable_vintr and renaming svm_{set,clear}_vintr to svm_{enable,disable}_vintr_window. Would you like to send two patches for this, the first to remove the WARN_ON and the second to do the cleanup? Thanks, Paolo > The code containing this warning was added in commit > > 64b5bd27042639dfcc1534f01771b7b871a02ffe > KVM: nSVM: ignore L1 interrupt window while running L2 with V_INTR_MASKING=1