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Peter Anvin" , Thomas Gleixner , Joerg Roedel , Suravee Suthikulpanit , Sean Christopherson , Maxim Levitsky , Robin Murphy , iommu@lists.linux.dev, Paolo Bonzini Subject: [PATCH v3 1/4] KVM: Add per vCPU flag specifying that a vCPU is loaded Date: Mon, 2 Oct 2023 14:57:20 +0300 Message-Id: <20231002115723.175344-2-mlevitsk@redhat.com> In-Reply-To: <20231002115723.175344-1-mlevitsk@redhat.com> References: <20231002115723.175344-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Mon, 02 Oct 2023 04:59:02 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1778683005806985278 X-GMAIL-MSGID: 1778683005806985278 Add vcpu->loaded boolean flag specifying that a vCPU is loaded. Such flag can be useful in a vendor code (e.g AVIC) to make decisions based on it. Signed-off-by: Maxim Levitsky --- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index fb6c6109fdcad69..331432d86e44d51 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -379,6 +379,7 @@ struct kvm_vcpu { #endif bool preempted; bool ready; + bool loaded; struct kvm_vcpu_arch arch; struct kvm_vcpu_stat stat; char stats_id[KVM_STATS_NAME_SIZE]; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 486800a7024b373..615f2a02b7cb97f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -214,6 +214,10 @@ void vcpu_load(struct kvm_vcpu *vcpu) __this_cpu_write(kvm_running_vcpu, vcpu); preempt_notifier_register(&vcpu->preempt_notifier); kvm_arch_vcpu_load(vcpu, cpu); + + /* Ensure that vcpu->cpu is visible before vcpu->loaded is set to true */ + smp_wmb(); + WRITE_ONCE(vcpu->loaded, true); put_cpu(); } EXPORT_SYMBOL_GPL(vcpu_load); @@ -221,6 +225,12 @@ EXPORT_SYMBOL_GPL(vcpu_load); void vcpu_put(struct kvm_vcpu *vcpu) { preempt_disable(); + WRITE_ONCE(vcpu->loaded, false); + /* + * Ensure that vcpu->loaded is set and visible, + * before KVM actually unloads the vCPU. + */ + smp_wmb(); kvm_arch_vcpu_put(vcpu); preempt_notifier_unregister(&vcpu->preempt_notifier); __this_cpu_write(kvm_running_vcpu, NULL);