From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C30EC761AF for ; Mon, 3 Apr 2023 14:34:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233587AbjDCOet (ORCPT ); Mon, 3 Apr 2023 10:34:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233032AbjDCOer (ORCPT ); Mon, 3 Apr 2023 10:34:47 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 784D8E74 for ; Mon, 3 Apr 2023 07:34:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C0C2AB81C8A for ; Mon, 3 Apr 2023 14:34:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 230B9C433D2; Mon, 3 Apr 2023 14:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680532455; bh=xBhRxDw30CyeAR3Q/IQudnXtFrYi0fww3SCrH8UTsIk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AjmQE39GPFxX+TKOGH1T+oUZ0wtOmgJoPPmxyFis+/MKCk88iDeKWtLf1SEWAKtvf Ld747deZp7qZVJsothUGfZo7LQSDv76yUDlFK2hWo7tfO18iPSvDnKkbvlqSKazIvd eVFLlYK8V1r8AD9tKmPG39AFOziiJywbydjAx1qk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sean Christopherson , Maxim Levitsky , Paolo Bonzini , syzbot+b6a74be92b5063a0f1ff@syzkaller.appspotmail.com, Tudor Ambarus Subject: [PATCH 5.15 90/99] KVM: VMX: Move preemption timer <=> hrtimer dance to common x86 Date: Mon, 3 Apr 2023 16:09:53 +0200 Message-Id: <20230403140406.748987144@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140356.079638751@linuxfoundation.org> References: <20230403140356.079638751@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sean Christopherson commit 98c25ead5eda5e9d41abe57839ad3e8caf19500c upstream. Handle the switch to/from the hypervisor/software timer when a vCPU is blocking in common x86 instead of in VMX. Even though VMX is the only user of a hypervisor timer, the logic and all functions involved are generic x86 (unless future CPUs do something completely different and implement a hypervisor timer that runs regardless of mode). Handling the switch in common x86 will allow for the elimination of the pre/post_blocks hooks, and also lets KVM switch back to the hypervisor timer if and only if it was in use (without additional params). Add a comment explaining why the switch cannot be deferred to kvm_sched_out() or kvm_vcpu_block(). Signed-off-by: Sean Christopherson Reviewed-by: Maxim Levitsky Message-Id: <20211208015236.1616697-8-seanjc@google.com> Signed-off-by: Paolo Bonzini [ta: Fix conflicts in vmx_pre_block and vmx_post_block as per Paolo's suggestion. Add Reported-by and Link tags.] Reported-by: syzbot+b6a74be92b5063a0f1ff@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=489beb3d76ef14cc6cd18125782dc6f86051a605 Tested-by: Tudor Ambarus Signed-off-by: Tudor Ambarus Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx/vmx.c | 6 ------ arch/x86/kvm/x86.c | 21 +++++++++++++++++++++ 2 files changed, 21 insertions(+), 6 deletions(-) --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7597,17 +7597,11 @@ static int vmx_pre_block(struct kvm_vcpu if (pi_pre_block(vcpu)) return 1; - if (kvm_lapic_hv_timer_in_use(vcpu)) - kvm_lapic_switch_to_sw_timer(vcpu); - return 0; } static void vmx_post_block(struct kvm_vcpu *vcpu) { - if (kvm_x86_ops.set_hv_timer) - kvm_lapic_switch_to_hv_timer(vcpu); - pi_post_block(vcpu); } --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10043,12 +10043,28 @@ out: static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu) { + bool hv_timer; + if (!kvm_arch_vcpu_runnable(vcpu) && (!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) { + /* + * Switch to the software timer before halt-polling/blocking as + * the guest's timer may be a break event for the vCPU, and the + * hypervisor timer runs only when the CPU is in guest mode. + * Switch before halt-polling so that KVM recognizes an expired + * timer before blocking. + */ + hv_timer = kvm_lapic_hv_timer_in_use(vcpu); + if (hv_timer) + kvm_lapic_switch_to_sw_timer(vcpu); + srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); kvm_vcpu_block(vcpu); vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); + if (hv_timer) + kvm_lapic_switch_to_hv_timer(vcpu); + if (kvm_x86_ops.post_block) static_call(kvm_x86_post_block)(vcpu); @@ -10287,6 +10303,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_v r = -EINTR; goto out; } + /* + * It should be impossible for the hypervisor timer to be in + * use before KVM has ever run the vCPU. + */ + WARN_ON_ONCE(kvm_lapic_hv_timer_in_use(vcpu)); kvm_vcpu_block(vcpu); if (kvm_apic_accept_events(vcpu) < 0) { r = 0;