From patchwork Fri Apr 14 23:44:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 13212048 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 60D05C77B7A for ; Fri, 14 Apr 2023 23:45:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230175AbjDNXps (ORCPT ); Fri, 14 Apr 2023 19:45:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230163AbjDNXpS (ORCPT ); Fri, 14 Apr 2023 19:45:18 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C2D6B476; Fri, 14 Apr 2023 16:44:41 -0700 (PDT) Message-ID: <20230414232310.194293270@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1681515880; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=U86WQCD4/7f+Xqtkcp8tab/f3Qs5fwP9mDOYJzY6GfM=; b=jVIvfWfMQ/Mv7TLWicCCZIBuoCNHTQbWP9agDzTG7YCSq254hUFkclQNrmhW3hMxwO6BPK vpCyMRIt4O1v+XPm4hgw1E/lo8bQ+TLMoWfNV6id2wkbLsusQC6+QgLxHkmM7jqI5M1i8u WMWTwhPBiMRMlROawAHv6lnZ2lJwgt69Ha2d7Hel7C6kpu8UPNf7d9bEsHq2W4HMj8o6m6 dmaviMmKfYNuICvE6NIhMG4fkMK+1VZcm9tvKGIXKcaFCzlTUjXnuorDCoZhFXx/Hy5zi8 WucVMkf4GaCQOYOvuAmNqRgA5o2nLyY6ILSN9/5KO2/baOF9ZKuCj7IpPwPGyQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1681515880; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=U86WQCD4/7f+Xqtkcp8tab/f3Qs5fwP9mDOYJzY6GfM=; b=bwxgSYDBNDOQrQ9qYJjd5x62eInfveDh14CbqLzga+9pzOoPfQod/ugWmc+ORstEOs2az4 q8XHnTNdR1jM1HBA== From: Thomas Gleixner To: LKML Cc: x86@kernel.org, David Woodhouse , Andrew Cooper , Brian Gerst , "Arjan van de Veen" , Paolo Bonzini , Paul McKenney , Tom Lendacky , Sean Christopherson , Oleksandr Natalenko , Paul Menzel , "Guilherme G. Piccoli" , Piotr Gorski , Juergen Gross , Boris Ostrovsky , xen-devel@lists.xenproject.org, David Woodhouse , Usama Arif , Russell King , Arnd Bergmann , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Guo Ren , linux-csky@vger.kernel.org, Thomas Bogendoerfer , linux-mips@vger.kernel.org, "James E.J. Bottomley" , Helge Deller , linux-parisc@vger.kernel.org, Paul Walmsley , Palmer Dabbelt , linux-riscv@lists.infradead.org, Mark Rutland , Sabin Rapan Subject: [patch 16/37] x86/xen/smp_pv: Remove wait for CPU online References: <20230414225551.858160935@linutronix.de> MIME-Version: 1.0 Date: Sat, 15 Apr 2023 01:44:39 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Now that the core code drops sparse_irq_lock after the idle thread synchronized, it's pointless to wait for the AP to mark itself online. Whether the control CPU runs in a wait loop or sleeps in the core code waiting for the online operation to complete makes no difference. Signed-off-by: Thomas Gleixner Cc: Juergen Gross Cc: Boris Ostrovsky Cc: xen-devel@lists.xenproject.org --- arch/x86/xen/smp_pv.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -340,11 +340,11 @@ static int xen_pv_cpu_up(unsigned int cp xen_pmu_init(cpu); - rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL); - BUG_ON(rc); - - while (cpu_report_state(cpu) != CPU_ONLINE) - HYPERVISOR_sched_op(SCHEDOP_yield, NULL); + /* + * Why is this a BUG? If the hypercall fails then everything can be + * rolled back, no? + */ + BUG_ON(HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)); return 0; }