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([2001:b07:6468:f312:cf8e:a9a0:1aed:9a37]) by smtp.gmail.com with ESMTPSA id f16sm3642510wrp.47.2020.09.16.06.05.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Sep 2020 06:05:41 -0700 (PDT) Subject: Re: [BUG] Migration hv_time rollback To: "Dr. David Alan Gilbert" , Antoine Damhet , vkuznets@redhat.com References: <20200916090602.blkm7eym6g5bnvvk@tartarus> <20200916112956.GE2833@work-vm> From: Paolo Bonzini Message-ID: <37b1b2b7-40f5-d0b1-2709-df9fe24fc65f@redhat.com> Date: Wed, 16 Sep 2020 15:05:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200916112956.GE2833@work-vm> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/16 02:35:56 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -51 X-Spam_score: -5.2 X-Spam_bar: ----- X-Spam_report: (-5.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.999, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.062, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , qemu-devel@nongnu.org, "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 16/09/20 13:29, Dr. David Alan Gilbert wrote: >> I have tracked the bug to the fact that `kvmclock` is not exposed and >> disabled from qemu PoV but is in fact used by `hv-time` (in KVM). >> >> I think we should enable the `kvmclock` (qemu device) if `hv-time` is >> present and add Hyper-V support for the `kvmclock_current_nsec` >> function. Yes, this seems correct. I would have to check but it may even be better to _always_ send kvmclock data in the live migration stream. Paolo