From patchwork Fri Oct 4 02:53:17 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Niethe X-Patchwork-Id: 1171525 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="I+7X8PFy"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46kvb61cbDz9sPw for ; Fri, 4 Oct 2019 12:53:54 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731004AbfJDCxx (ORCPT ); Thu, 3 Oct 2019 22:53:53 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:34015 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730309AbfJDCxw (ORCPT ); Thu, 3 Oct 2019 22:53:52 -0400 Received: by mail-pl1-f196.google.com with SMTP id k7so2449249pll.1 for ; Thu, 03 Oct 2019 19:53:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=pw20gjwGyIvk4z43y2bV2DrT/I4s7wENPGMcRRJ5rbU=; b=I+7X8PFymt8BYtwV6VPllwcWxilbTowRfL8xWjjgfRDnyc1vOoMFchC9SqBarrsgAm 6ghMr6iSAVYWfyXYZbtwpFaL5m10QOx0SvNLbUCf9yzu6zmtGnOMiZE/eqwVAxvT/ZlR gnn2mvEePlMKHVn4PrCP+n8V7eYsHkjxVZBrZPDMjU4037JYe1NYNSKwe5OrcOgJb53m wDUSQw+7WwmK/vaxvYN1EoaKjv/qX4ZZOP1m+OwAZdYXoRVhVKdPYKqVQ0LJOjC/2t3s BSkFO5qdHDD9ZG/obz7Th/peMJBH7WXnmUwJvGCAEIdSzgKaM/Z6nBbDR9p4KMEnLiA4 kNrQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=pw20gjwGyIvk4z43y2bV2DrT/I4s7wENPGMcRRJ5rbU=; b=M81kM+CA4mGSHgo9xEPcRQ2W8tWNrTT/11CQGha9/c2i0CHKLe8DW0cMN+BTfBRBx8 sv9sz9UZho4l17GwNbV7I6xQ3Ko/CcNfRVfytTdn9stmDH/JUaoX23DZmYtJA/NbiRDh EjC5dwMcooixZY/tl+qvu0xvBd2F0FpjAeoCo067BFUQoBri3AtwR8nNrsdGWfpfKquT e9SslKttJrdvxuceLYdxiIZsJLt43+36tvH+TkD+NPSCptI1dXMAiw4EVMP9pURpOHuS Z+2kF5/dOf1so2v6GulWBKBLpYYLH3OGyC8ZksS0heWk2vcipQzrvpvJZtu/M7GlktGZ qjPg== X-Gm-Message-State: APjAAAW44tdMlp6LX1tUaWDJ0QZYIPrFG8/8NrBvcWi7i45WyxsjLtK7 tFxvutl/Ww8LHjdEInLrNzc= X-Google-Smtp-Source: APXvYqz+Wnmy5oq8K1YLi07YGFVPhyMZPZ0qDgQMDHCzmadww+fy1WVnAmWycWvQyFJxrLfO/vp3nA== X-Received: by 2002:a17:902:ff18:: with SMTP id f24mr12839898plj.173.1570157632027; Thu, 03 Oct 2019 19:53:52 -0700 (PDT) Received: from pasglop.ozlabs.ibm.com ([122.99.82.10]) by smtp.gmail.com with ESMTPSA id d20sm6920181pfq.88.2019.10.03.19.53.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Oct 2019 19:53:51 -0700 (PDT) From: Jordan Niethe To: linuxppc-dev@lists.ozlabs.org Cc: patch-notifications@ellerman.id.au, paulus@ozlabs.org, alistair@popple.id.au, kvm-ppc@vger.kernel.org, aik@ozlabs.ru, Jordan Niethe Subject: [PATCH] powerpc/kvm: Fix kvmppc_vcore->in_guest value in kvmhv_switch_to_host Date: Fri, 4 Oct 2019 12:53:17 +1000 Message-Id: <20191004025317.19340-1-jniethe5@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org kvmhv_switch_to_host() in arch/powerpc/kvm/book3s_hv_rmhandlers.S needs to set kvmppc_vcore->in_guest to 0 to signal secondary CPUs to continue. This happens after resetting the PCR. Before commit 13c7bb3c57dc ("powerpc/64s: Set reserved PCR bits"), r0 would always be 0 before it was stored to kvmppc_vcore->in_guest. However because of this change in the commit: /* Reset PCR */ ld r0, VCORE_PCR(r5) - cmpdi r0, 0 + LOAD_REG_IMMEDIATE(r6, PCR_MASK) + cmpld r0, r6 beq 18f - li r0, 0 - mtspr SPRN_PCR, r0 + mtspr SPRN_PCR, r6 18: /* Signal secondary CPUs to continue */ stb r0,VCORE_IN_GUEST(r5) We are no longer comparing r0 against 0 and loading it with 0 if it contains something else. Hence when we store r0 to kvmppc_vcore->in_guest, it might not be 0. This means that secondary CPUs will not be signalled to continue. Those CPUs get stuck and errors like the following are logged: KVM: CPU 1 seems to be stuck KVM: CPU 2 seems to be stuck KVM: CPU 3 seems to be stuck KVM: CPU 4 seems to be stuck KVM: CPU 5 seems to be stuck KVM: CPU 6 seems to be stuck KVM: CPU 7 seems to be stuck This can be reproduced with: $ for i in `seq 1 7` ; do chcpu -d $i ; done ; $ taskset -c 0 qemu-system-ppc64 -smp 8,threads=8 \ -M pseries,accel=kvm,kvm-type=HV -m 1G -nographic -vga none \ -kernel vmlinux -initrd initrd.cpio.xz Fix by making sure r0 is 0 before storing it to kvmppc_vcore->in_guest. Fixes: 13c7bb3c57dc ("powerpc/64s: Set reserved PCR bits") Reported-by: Alexey Kardashevskiy Signed-off-by: Jordan Niethe Reviewed-by: Alistair Popple Tested-by: Alexey Kardashevskiy Reviewed-by: Alistair Popple --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 74a9cfe84aee..faebcbb8c4db 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1921,6 +1921,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) mtspr SPRN_PCR, r6 18: /* Signal secondary CPUs to continue */ + li r0, 0 stb r0,VCORE_IN_GUEST(r5) 19: lis r8,0x7fff /* MAX_INT@h */ mtspr SPRN_HDEC,r8