From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v7 13/13] KVM: x86: Disable Intel Processor Trace when VMXON in L1 guest Date: Fri, 4 May 2018 23:49:00 +0200 Message-ID: <42da55ab-aefb-aa3c-bfed-d6f0457db798@redhat.com> References: <1525349323-9938-1-git-send-email-luwei.kang@intel.com> <1525349323-9938-14-git-send-email-luwei.kang@intel.com> <20180504102358.eojiggqrnhxng2ru@um.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, rkrcmar@redhat.com, linux-kernel@vger.kernel.org, joro@8bytes.org, peterz@infradead.org, chao.p.peng@linux.intel.com To: Alexander Shishkin , Luwei Kang Return-path: In-Reply-To: <20180504102358.eojiggqrnhxng2ru@um.fi.intel.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/05/2018 12:23, Alexander Shishkin wrote: >> Currently, Intel Processor Trace do not support tracing in L1 guest >> VMX operation(IA32_VMX_MISC[bit 14] is 0). As mentioned in SDM, > I don't understand this patch. You mention VMX_MISC[14] here, but I > can't see anything related to it in the code. This is talking about the _guest_'s view of IA32_VMX_MISC. The code does nothing to set it, so the patch does what the commit message says below: >> on these type of processors, execution of the VMXON instruction will >> clears IA32_RTIT_CTL.TraceEn and any attempt to write IA32_RTIT_CTL >> causes a general-protection exception (#GP). >> >> Signed-off-by: Luwei Kang Thanks, Paolo