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([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.googlemail.com with ESMTPSA id b2-20020a1709063ca200b0073095b4b758sm1090273ejh.218.2022.08.09.05.59.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Aug 2022 05:59:13 -0700 (PDT) Message-ID: <43e258cc-71ac-bde4-d1f8-9eb9519928d3@redhat.com> Date: Tue, 9 Aug 2022 14:59:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 Subject: Re: [PATCH v3 2/2] KVM: x86/xen: Stop Xen timer before changing IRQ Content-Language: en-US To: David Woodhouse , Coleman Dietsch , kvm@vger.kernel.org Cc: Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, Pavel Skripkin , linux-kernel-mentees@lists.linuxfoundation.org, stable@vger.kernel.org, syzbot+e54f930ed78eb0f85281@syzkaller.appspotmail.com References: <20220808190607.323899-2-dietschc@csp.edu> <20220808190607.323899-3-dietschc@csp.edu> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/9/22 11:22, David Woodhouse wrote: > On Mon, 2022-08-08 at 14:06 -0500, Coleman Dietsch wrote: >> Stop Xen timer (if it's running) prior to changing the IRQ vector and >> potentially (re)starting the timer. Changing the IRQ vector while the >> timer is still running can result in KVM injecting a garbage event, e.g. >> vm_xen_inject_timer_irqs() could see a non-zero xen.timer_pending from >> a previous timer but inject the new xen.timer_virq. > > Hm, wasn't that already addressed in the first patch I saw, which just > called kvm_xen_stop_timer() unconditionally before (possibly) setting > it up again? Which patch is that? Paolo