From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932865AbcIBRAu (ORCPT ); Fri, 2 Sep 2016 13:00:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51394 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932236AbcIBRAs (ORCPT ); Fri, 2 Sep 2016 13:00:48 -0400 Subject: Re: [PATCH 4/4] kvm: x86: export TSC offset to user-space To: Luiz Capitulino , kvm@vger.kernel.org References: <1472663145-1835-1-git-send-email-lcapitulino@redhat.com> <1472663145-1835-5-git-send-email-lcapitulino@redhat.com> Cc: linux-kernel@vger.kernel.org, rkrcmar@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org, mtosatti@redhat.com From: Paolo Bonzini Message-ID: <03966aad-cf0d-6f0c-f306-aef31c4078a7@redhat.com> Date: Fri, 2 Sep 2016 19:00:41 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <1472663145-1835-5-git-send-email-lcapitulino@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 02 Sep 2016 17:00:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/08/2016 19:05, Luiz Capitulino wrote: > vcpu0: 18446742405270834952 > vcpu1: 18446742405270834952 > vcpu2: 18446742405270834952 > vcpu3: 18446742405270834952 > > - We'll probably need to export the TSC multiplier too. > However, I've been using only the TSC offset for now. > So, let's get this merged first and do the TSC multiplier > as a second step You'll need to export the number of fractional bits in the multiplier, too. It's going to be a very simple patch, so please do everything now. arch/x86/kvm/x86.c is huge; please create a new file arch/x86/kvm/debugfs.c. > Signed-off-by: Luiz Capitulino > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/svm.c | 1 + > arch/x86/kvm/vmx.c | 8 ++++++++ > arch/x86/kvm/x86.c | 30 ++++++++++++++++++++++++++++++ > 4 files changed, 40 insertions(+) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 33ae3a4..5714bbd 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -952,6 +952,7 @@ struct kvm_x86_ops { > bool (*has_wbinvd_exit)(void); > > u64 (*read_tsc_offset)(struct kvm_vcpu *vcpu); > + u64 (*read_cached_tsc_offset)(struct kvm_vcpu *vcpu); > void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset); > > u64 (*read_l1_tsc)(struct kvm_vcpu *vcpu, u64 host_tsc); > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index af523d8..c851477 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -5065,6 +5065,7 @@ static struct kvm_x86_ops svm_x86_ops = { > .has_wbinvd_exit = svm_has_wbinvd_exit, > > .read_tsc_offset = svm_read_tsc_offset, > + .read_cached_tsc_offset = svm_read_tsc_offset, > .write_tsc_offset = svm_write_tsc_offset, > .adjust_tsc_offset_guest = svm_adjust_tsc_offset_guest, > .read_l1_tsc = svm_read_l1_tsc, > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 5cede40..82dfe42 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -616,6 +616,7 @@ struct vcpu_vmx { > u64 hv_deadline_tsc; > > u64 current_tsc_ratio; > + u64 cached_tsc_offset; > > bool guest_pkru_valid; > u32 guest_pkru; > @@ -2608,6 +2609,11 @@ static u64 vmx_read_tsc_offset(struct kvm_vcpu *vcpu) > return vmcs_read64(TSC_OFFSET); > } > > +static u64 vmx_read_cached_tsc_offset(struct kvm_vcpu *vcpu) > +{ > + return to_vmx(vcpu)->cached_tsc_offset; > +} > + > /* > * writes 'offset' into guest's timestamp counter offset register > */ > @@ -2632,6 +2638,7 @@ static void vmx_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset) > vmcs_read64(TSC_OFFSET), offset); > vmcs_write64(TSC_OFFSET, offset); > } > + to_vmx(vcpu)->cached_tsc_offset = offset; > } > > static void vmx_adjust_tsc_offset_guest(struct kvm_vcpu *vcpu, s64 adjustment) > @@ -11275,6 +11282,7 @@ static struct kvm_x86_ops vmx_x86_ops = { > .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit, > > .read_tsc_offset = vmx_read_tsc_offset, > + .read_cached_tsc_offset = vmx_read_cached_tsc_offset, > .write_tsc_offset = vmx_write_tsc_offset, > .adjust_tsc_offset_guest = vmx_adjust_tsc_offset_guest, > .read_l1_tsc = vmx_read_l1_tsc, You need to handle SVM as well. So you might as well simplify the code: - add a kvm_vcpu_write_tsc_offset wrapper for kvm_x86_ops->write_tsc_offset - add a tsc_offset field in struct kvm_vcpu_arch - replace kvm_x86_ops->read_tsc_offset with accesses to the new field Then in a fifth patch export the TSC offset (and multiplier ;)) to userspace. I'm not very happy about having a single file for all TSC offsets. Creating subdirectories under the PID-FD per-VM directory would be nicer in the long run. Paolo