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 lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EBB05C982FA for ; Wed, 23 Sep 2026 11:28:42 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x9L8w-0001Gu-Bm; Wed, 23 Sep 2026 07:28:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1x9L8o-0001GV-Rr for qemu-devel@nongnu.org; Wed, 23 Sep 2026 07:27:58 -0400 Received: from linux.microsoft.com ([13.77.154.182]) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1x9L8j-0000E5-5p for qemu-devel@nongnu.org; Wed, 23 Sep 2026 07:27:57 -0400 Received: from example.com (unknown [167.220.208.66]) by linux.microsoft.com (Postfix) with ESMTPSA id 67BF120B7168; Wed, 23 Sep 2026 04:26:59 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 67BF120B7168 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1790162820; bh=PMWAOuTEXXnJ0sZoYdpLHdpG3urFjnkjpUgV0G4FqAA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=m0X4/wup97EZrULoRLPBLZZfBLgxOoduW5qKXOQBDqrDI17fdXG43uJo1107twlm5 S2NhgTMyeAAzTI/9VZ8eZ7MdzHnc0AC5FcOIEqD9Sn0NDZnNMfuC3ZRo32xIxzY3Ir YTSRZMwgarc46m4qYQrB/0TGUdCfuBcWR/a7p2P4= Date: Wed, 23 Sep 2026 13:27:44 +0200 From: Magnus Kulke To: Doru =?iso-8859-1?Q?Bl=E2nzeanu?= Cc: qemu-devel@nongnu.org, Wei Liu , Wei Liu , Magnus Kulke , Doru =?iso-8859-1?Q?Bl=E2nzeanu?= Subject: Re: [PATCH v2 4/4] accel/mshv: break the vCPU run loop on exit_request Message-ID: References: <20260731184643.89604-1-dblanzeanu@linux.microsoft.com> <20260731184643.89604-5-dblanzeanu@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260731184643.89604-5-dblanzeanu@linux.microsoft.com> Received-SPF: pass client-ip=13.77.154.182; envelope-from=magnuskulke@linux.microsoft.com; helo=linux.microsoft.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, SPF_HELO_PASS=-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: qemu development 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Jul 31, 2026 at 09:46:42PM +0300, Doru Blânzeanu wrote: > Ignored VM exits can cause mshv_cpu_exec() to re-enter MSHV_RUN_VP > without returning to qemu_process_cpu_events(). A busy vCPU may > prevent pause_all_vcpus() from completing. > > Check exit_request before re-entering MSHV_RUN_VP and return > EXCP_INTERRUPT so pending stop requests can be processed. > > Signed-off-by: Doru Blânzeanu > --- > accel/mshv/mshv-all.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c > index afcb87b3b8..b7c1126fe0 100644 > --- a/accel/mshv/mshv-all.c > +++ b/accel/mshv/mshv-all.c > @@ -780,6 +780,16 @@ static int mshv_cpu_exec(CPUState *cpu) > cpu->vcpu_dirty = false; > } > > + /* > + * A kick/stop can't reliably break MSHV_RUN_VP out, so leave the run > + * loop here too; otherwise a busy vCPU never reaches > + * qemu_process_cpu_events() and pause_all_vcpus() hangs under the BQL. > + */ > + if (cpu->stop || qatomic_load_acquire(&cpu->exit_request)) { > + ret = EXCP_INTERRUPT; > + break; > + } > + > ret = mshv_run_vcpu(mshv_state->vm, cpu, &mshv_msg, &exit_reason); > if (ret < 0) { > error_report("Failed to run on vcpu %d", cpu->cpu_index); > -- > 2.53.0 This is already fixed in upstream. checking the cpu->stop flag doesn't seem to be required and other accelerators do not seem to check it either. We agreed to drop this patch for now.