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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id kx22-20020a170907775600b0078ba492db81sm975153ejc.9.2022.10.07.02.26.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Oct 2022 02:26:15 -0700 (PDT) From: Vitaly Kuznetsov To: qemu-devel@nongnu.org, Paolo Bonzini Cc: Marcelo Tosatti , Oliver Upton , Maxim Levitsky Subject: Re: [PATCH] i386: Fix KVM_CAP_ADJUST_CLOCK capability check In-Reply-To: <87wn9pkv6e.fsf@redhat.com> References: <20220920144024.3559708-1-vkuznets@redhat.com> <87wn9pkv6e.fsf@redhat.com> Date: Fri, 07 Oct 2022 11:26:14 +0200 Message-ID: <87sfk07znt.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Received-SPF: pass client-ip=170.10.133.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Vitaly Kuznetsov writes: > Vitaly Kuznetsov writes: > >> KVM commit c68dc1b577ea ("KVM: x86: Report host tsc and realtime values in >> KVM_GET_CLOCK") broke migration of certain workloads, e.g. Win11 + WSL2 >> guest reboots immediately after migration. KVM, however, is not to >> blame this time. When KVM_CAP_ADJUST_CLOCK capability is checked, the >> result is all supported flags (which the above mentioned KVM commit >> enhanced) but kvm_has_adjust_clock_stable() wants it to be >> KVM_CLOCK_TSC_STABLE precisely. The result is that 'clock_is_reliable' >> is not set in vmstate and the saved clock reading is discarded in >> kvmclock_vm_state_change(). >> >> Signed-off-by: Vitaly Kuznetsov >> --- >> target/i386/kvm/kvm.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c >> index a1fd1f53791d..c33192a87dcb 100644 >> --- a/target/i386/kvm/kvm.c >> +++ b/target/i386/kvm/kvm.c >> @@ -157,7 +157,7 @@ bool kvm_has_adjust_clock_stable(void) >> { >> int ret = kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK); >> >> - return (ret == KVM_CLOCK_TSC_STABLE); >> + return ret & KVM_CLOCK_TSC_STABLE; >> } >> >> bool kvm_has_adjust_clock(void) > > Ping) This issue seems to introduce major migration issues with KVM >= v5.16 Ping) -- Vitaly