From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57553) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ew63I-0003uD-Ag for qemu-devel@nongnu.org; Wed, 14 Mar 2018 09:02:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ew63F-00065J-9l for qemu-devel@nongnu.org; Wed, 14 Mar 2018 09:02:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37462) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ew63F-00065A-3r for qemu-devel@nongnu.org; Wed, 14 Mar 2018 09:02:41 -0400 Date: Wed, 14 Mar 2018 10:02:38 -0300 From: Eduardo Habkost Message-ID: <20180314130238.GE3417@localhost.localdomain> References: <1520969191-18162-1-git-send-email-luwei.kang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1520969191-18162-1-git-send-email-luwei.kang@intel.com> Subject: Re: [Qemu-devel] [PATCH] i386: Disable Intel PT if packets IP payloads have LIP values List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Luwei Kang Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, rth@twiddle.net On Wed, Mar 14, 2018 at 03:26:31AM +0800, Luwei Kang wrote: > Intel processor trace should be disabled when > CPUID.(EAX=14H,ECX=0H).ECX.[bit31] is set. > Generated packets which contain IP payloads will have LIP > values when this bit is set, or IP payloads will have RIP > values. > Currently, The information of CPUID 14H is constant to make > live migration safty and this bit is always 0 in guest even > if host support LIP values. > Guest sees the bit is 0 will expect IP payloads with RIP > values, but the host CPU will generate IP payloads with > LIP values if this bit is set in HW. > To make sure the value of IP payloads correctly, Intel PT > should be disabled when bit[31] is set. > > Signed-off-by: Luwei Kang Queued, thanks. -- Eduardo