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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 43B4BC4167B for ; Tue, 20 Dec 2022 12:39:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=YUnY1tuyyYVgDML9u4c1hHBmSQGfqd83y9+LwLh0eqU=; b=D4MWf1+H4aQXyy jGWxt0nt4YpWcX5QIKlFR76bjEYiFNND0kLSXHseGGXpkzzXQvphQZfIpBnKivkstKbT73A4KFJpb 2MwZNA/Sl4i7hHwYMTUpghNIO/cJreJdMgyd12VbY3QDUC7HZBOw2Om61s5FdlQ4K1ukHOpV8sJ5l ruEpuIH1WuH13ZvIrIy/THmHkpdZv2dY+Vk9itxUiBC9jn9fO64e7w2/p+MG6dSyfTGy0e/holaTT xrQbP2av5aXODmjHdV8BTCc6k6eY1C5YndPE17pUxkoiGAvuORQZ3O3hHzNy+Ia6XU4oEzJnko75w wLtDjrDdFmOKb1hYudfA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p7bta-00Ex8P-T0; Tue, 20 Dec 2022 12:38:58 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p7btT-00Ewy0-GE for kexec@lists.infradead.org; Tue, 20 Dec 2022 12:38:52 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1671539930; 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: in-reply-to:in-reply-to:references:references; bh=2YGLPYrhUM3liQYpN3p/+bDVBoiicBenOmdXkygbdC0=; b=ZofDCtM9217rEe1oEmKfLTzu6VqEVqy5ahDNJFewvpLugh993UzGBFtaqL/ad1h/tj8Ox5 aGcxJ9NHQLBTGbf9OTnWXHR+Dj1LZhjYXDlKwTeGw85JkQFUJMX5cBWyieDJUoo/AUudYw KMMO2suKkZjQ/bK+lBYENDSa6vQ9NWk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-561-hvM0dMytMiWl0AERQdiC_g-1; Tue, 20 Dec 2022 07:38:44 -0500 X-MC-Unique: hvM0dMytMiWl0AERQdiC_g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 04002183B3C3; Tue, 20 Dec 2022 12:38:44 +0000 (UTC) Received: from localhost (ovpn-12-53.pek2.redhat.com [10.72.12.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 30D8240C201B; Tue, 20 Dec 2022 12:38:42 +0000 (UTC) Date: Tue, 20 Dec 2022 20:38:39 +0800 From: Baoquan He To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , x86@kernel.org, kexec@lists.infradead.org, dgilbert@redhat.com Subject: Re: [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support" Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221220_043851_655174_E10F5CBF X-CRM114-Status: GOOD ( 15.46 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 12/20/22 at 12:38pm, Peter Zijlstra wrote: > On Tue, Dec 20, 2022 at 01:34:58PM +0800, Baoquan He wrote: > > This reverts commit 43931d350f30c6cd8c2f498d54ef7d65750abc92. > > > > On kvm guest with 4 cpus deployed, when adding 'nr_cpus=2' to normal > > kernel's cmdline, and triggering crash to jump to kdump kernel, kdump > > kernel will stably hang. Reverting commit 43931d350f30 ("x86/apic/x2apic: > > Implement IPI shorthands support") can fix it. > > > > The problem will disappear if removing 'nr_cpus=2' from normal kerne's > > cmdline. > > And the root cause for this is... ? Does the kvm x2apic emulation > somehow get upset when we shorthand CPUs that haven't been initialized? Thanks for checking. I haven't figure out the root cause. I haven't read the apic code for long time, and not familiar with the kvm code. So raise the issue to upstream. I can do testing if any suggestion. Add our virt dev Dr. David Alan Gilbert to CC. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec