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 A6BE1EB64D7 for ; Mon, 26 Jun 2023 18:38:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232446AbjFZSix (ORCPT ); Mon, 26 Jun 2023 14:38:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232475AbjFZSir (ORCPT ); Mon, 26 Jun 2023 14:38:47 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 31A1619AB for ; Mon, 26 Jun 2023 11:38:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C7C0F60E8D for ; Mon, 26 Jun 2023 18:38:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1E55C433C9; Mon, 26 Jun 2023 18:38:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1687804716; bh=+OuxsiHWDK4OKZ74d89J3eV8v9xsvgozHG3hxU+frI0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zMxf0Ww9Xc0+vNfu0uDrkBh7p48CNbA7yg4NwlB0r5nAhg962AodogD+iPNddG1lx 2itMx+7800WmoxEFeA8PMR1k0b0qSGno2lf0Vatj9XIhNhh0Wn7KyDpqIYyqkjIZQH FPdWl7UFbxCPPnlQTHfQn5E3IYkII0xj1KOovcng= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, John Starks , Michael Kelley , Vitaly Kuznetsov , Wei Liu Subject: [PATCH 5.15 18/96] Drivers: hv: vmbus: Fix vmbus_wait_for_unload() to scan present CPUs Date: Mon, 26 Jun 2023 20:11:33 +0200 Message-ID: <20230626180747.687262766@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230626180746.943455203@linuxfoundation.org> References: <20230626180746.943455203@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: Michael Kelley commit 320805ab61e5f1e2a5729ae266e16bec2904050c upstream. vmbus_wait_for_unload() may be called in the panic path after other CPUs are stopped. vmbus_wait_for_unload() currently loops through online CPUs looking for the UNLOAD response message. But the values of CONFIG_KEXEC_CORE and crash_kexec_post_notifiers affect the path used to stop the other CPUs, and in one of the paths the stopped CPUs are removed from cpu_online_mask. This removal happens in both x86/x64 and arm64 architectures. In such a case, vmbus_wait_for_unload() only checks the panic'ing CPU, and misses the UNLOAD response message except when the panic'ing CPU is CPU 0. vmbus_wait_for_unload() eventually times out, but only after waiting 100 seconds. Fix this by looping through *present* CPUs in vmbus_wait_for_unload(). The cpu_present_mask is not modified by stopping the other CPUs in the panic path, nor should it be. Also, in a CoCo VM the synic_message_page is not allocated in hv_synic_alloc(), but is set and cleared in hv_synic_enable_regs() and hv_synic_disable_regs() such that it is set only when the CPU is online. If not all present CPUs are online when vmbus_wait_for_unload() is called, the synic_message_page might be NULL. Add a check for this. Fixes: cd95aad55793 ("Drivers: hv: vmbus: handle various crash scenarios") Cc: stable@vger.kernel.org Reported-by: John Starks Signed-off-by: Michael Kelley Reviewed-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/1684422832-38476-1-git-send-email-mikelley@microsoft.com Signed-off-by: Wei Liu Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -827,11 +827,22 @@ static void vmbus_wait_for_unload(void) if (completion_done(&vmbus_connection.unload_event)) goto completed; - for_each_online_cpu(cpu) { + for_each_present_cpu(cpu) { struct hv_per_cpu_context *hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu); + /* + * In a CoCo VM the synic_message_page is not allocated + * in hv_synic_alloc(). Instead it is set/cleared in + * hv_synic_enable_regs() and hv_synic_disable_regs() + * such that it is set only when the CPU is online. If + * not all present CPUs are online, the message page + * might be NULL, so skip such CPUs. + */ page_addr = hv_cpu->synic_message_page; + if (!page_addr) + continue; + msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT; @@ -865,11 +876,14 @@ completed: * maybe-pending messages on all CPUs to be able to receive new * messages after we reconnect. */ - for_each_online_cpu(cpu) { + for_each_present_cpu(cpu) { struct hv_per_cpu_context *hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu); page_addr = hv_cpu->synic_message_page; + if (!page_addr) + continue; + msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT; msg->header.message_type = HVMSG_NONE; }