From patchwork Mon Oct 8 05:30:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Mackerras X-Patchwork-Id: 10630019 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C8A1E14BD for ; Mon, 8 Oct 2018 05:31:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BB67B28AEB for ; Mon, 8 Oct 2018 05:31:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AFA4A28B80; Mon, 8 Oct 2018 05:31:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 45DE528AEB for ; Mon, 8 Oct 2018 05:31:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726610AbeJHMla (ORCPT ); Mon, 8 Oct 2018 08:41:30 -0400 Received: from ozlabs.org ([203.11.71.1]:60515 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725941AbeJHMl3 (ORCPT ); Mon, 8 Oct 2018 08:41:29 -0400 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPSA id 42T89d3jc4zB2xk; Mon, 8 Oct 2018 16:31:33 +1100 (AEDT) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ozlabs.org; s=201707; t=1538976693; bh=rhwZmTbPSGXuqzu5MmIcPN2GrDUqIBi5Ktej1eXaNjA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H64xrfxDFUsV3Q15mdeuKqXzHKcxnYXyDv+W+slKjCaEfNCeFf7aQKrRXQijCJQrQ Ni4dk+ySQYu/DHxXNvkkyhMiYwSc29WjQM1/D0V/J1DIPGxyl1JB8sT+47PobNRqfL bpeuHKcXn3/LCkA4DJ2IPITYDIjTQbTx5W5yRlDg7GoNmU2XGEw4LMXxHEg3I9gGvw 9QC61k+wHc9qnJXJJNWCVK9eIg0bPNdvv/UQNd0l9p8IB/sBcVNe6l8JTxn3FidkN/ zR5AFt/K27FXm5nn3uvo3yYWoThdG83xgGGqFP1H640JrCacbMTRaegZtlUhs8W2RG qzkTYq1yS144Q== From: Paul Mackerras To: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org Cc: David Gibson , linuxppc-dev@ozlabs.org Subject: [PATCH v5 08/33] KVM: PPC: Book3S HV: Call kvmppc_handle_exit_hv() with vcore unlocked Date: Mon, 8 Oct 2018 16:30:54 +1100 Message-Id: <1538976679-1363-9-git-send-email-paulus@ozlabs.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1538976679-1363-1-git-send-email-paulus@ozlabs.org> References: <1538976679-1363-1-git-send-email-paulus@ozlabs.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently kvmppc_handle_exit_hv() is called with the vcore lock held because it is called within a for_each_runnable_thread loop. However, we already unlock the vcore within kvmppc_handle_exit_hv() under certain circumstances, and this is safe because (a) any vcpus that become runnable and are added to the runnable set by kvmppc_run_vcpu() have their vcpu->arch.trap == 0 and can't actually run in the guest (because the vcore state is VCORE_EXITING), and (b) for_each_runnable_thread is safe against addition or removal of vcpus from the runnable set. Therefore, in order to simplify things for following patches, let's drop the vcore lock in the for_each_runnable_thread loop, so kvmppc_handle_exit_hv() gets called without the vcore lock held. Reviewed-by: David Gibson Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 49a686c..0e17593 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1084,7 +1084,6 @@ static int kvmppc_emulate_doorbell_instr(struct kvm_vcpu *vcpu) return RESUME_GUEST; } -/* Called with vcpu->arch.vcore->lock held */ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, struct task_struct *tsk) { @@ -1205,10 +1204,7 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, swab32(vcpu->arch.emul_inst) : vcpu->arch.emul_inst; if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) { - /* Need vcore unlocked to call kvmppc_get_last_inst */ - spin_unlock(&vcpu->arch.vcore->lock); r = kvmppc_emulate_debug_inst(run, vcpu); - spin_lock(&vcpu->arch.vcore->lock); } else { kvmppc_core_queue_program(vcpu, SRR1_PROGILL); r = RESUME_GUEST; @@ -1224,12 +1220,8 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu, case BOOK3S_INTERRUPT_H_FAC_UNAVAIL: r = EMULATE_FAIL; if (((vcpu->arch.hfscr >> 56) == FSCR_MSGP_LG) && - cpu_has_feature(CPU_FTR_ARCH_300)) { - /* Need vcore unlocked to call kvmppc_get_last_inst */ - spin_unlock(&vcpu->arch.vcore->lock); + cpu_has_feature(CPU_FTR_ARCH_300)) r = kvmppc_emulate_doorbell_instr(vcpu); - spin_lock(&vcpu->arch.vcore->lock); - } if (r == EMULATE_FAIL) { kvmppc_core_queue_program(vcpu, SRR1_PROGILL); r = RESUME_GUEST; @@ -2599,6 +2591,14 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) spin_lock(&vc->lock); now = get_tb(); for_each_runnable_thread(i, vcpu, vc) { + /* + * It's safe to unlock the vcore in the loop here, because + * for_each_runnable_thread() is safe against removal of + * the vcpu, and the vcore state is VCORE_EXITING here, + * so any vcpus becoming runnable will have their arch.trap + * set to zero and can't actually run in the guest. + */ + spin_unlock(&vc->lock); /* cancel pending dec exception if dec is positive */ if (now < vcpu->arch.dec_expires && kvmppc_core_pending_dec(vcpu)) @@ -2614,6 +2614,7 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) vcpu->arch.ret = ret; vcpu->arch.trap = 0; + spin_lock(&vc->lock); if (is_kvmppc_resume_guest(vcpu->arch.ret)) { if (vcpu->arch.pending_exceptions) kvmppc_core_prepare_to_enter(vcpu);