From patchwork Fri Jun 28 18:51:22 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 255627 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 8D49F2C0090 for ; Sat, 29 Jun 2013 04:59:55 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Usdtd-0007Ih-8o; Fri, 28 Jun 2013 18:59:49 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Usdse-0006jG-EE for kernel-team@lists.ubuntu.com; Fri, 28 Jun 2013 18:58:48 +0000 Received: from c-67-160-231-42.hsd1.ca.comcast.net ([67.160.231.42] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UsdmW-0007ZU-RO; Fri, 28 Jun 2013 18:52:29 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1UsdmU-0006Y6-Qw; Fri, 28 Jun 2013 11:52:26 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 060/105] x86: kvmclock: zero initialize pvclock shared memory area Date: Fri, 28 Jun 2013 11:51:22 -0700 Message-Id: <1372445527-24414-61-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1372445527-24414-1-git-send-email-kamal@canonical.com> References: <1372445527-24414-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Cc: Igor Mammedov , Kamal Mostafa , Paolo Bonzini X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.8.13.4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Igor Mammedov commit 07868fc6aaf57847b0f3a3d53086b7556eb83f4a upstream. kernel might hung in pvclock_clocksource_read() due to uninitialized memory might contain odd version value in following cycle: do { version = __pvclock_read_cycles(src, &ret, &flags); } while ((src->version & 1) || version != src->version); if secondary kvmclock is accessed before it's registered with kvm. Clear garbage in pvclock shared memory area right after it's allocated to avoid this issue. Ref: https://bugzilla.kernel.org/show_bug.cgi?id=59521 Signed-off-by: Igor Mammedov [See BZ for analysis. We may want a different fix for 3.11, but this is the safest for now - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Kamal Mostafa --- arch/x86/kernel/kvmclock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 5bedbdd..a855a2e 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -238,6 +238,7 @@ void __init kvmclock_init(void) if (!mem) return; hv_clock = __va(mem); + memset(hv_clock, 0, size); if (kvm_register_clock("boot clock")) { hv_clock = NULL;