From patchwork Thu Dec 3 17:11:17 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Maxim Levitsky X-Patchwork-Id: 337270 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B8596C0018C for ; Thu, 3 Dec 2020 17:13:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87F78206D5 for ; Thu, 3 Dec 2020 17:13:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2501950AbgLCRNg (ORCPT ); Thu, 3 Dec 2020 12:13:36 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:51354 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728925AbgLCRNf (ORCPT ); Thu, 3 Dec 2020 12:13:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607015528; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6hX5d7i1onM6KJjcxjt4YgWrUzJK2cIDgrBlA7uN5Mk=; b=MDzMptkIb51QzHUWu7AbFpA5KAhqkqvqW634w553OfQFwFEE3HK7Tzzn69XFElrD0CcikO Nos/r6ApkyvlF4CGhPALJqbyri9yDAPtH1f/bQFFVnMwtB1QuCNu43yGDXLvc/C8KPmCgf sMCNourTkI1D2+kWc7Fm4K5xVQFl8tI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-270-mzLNlnliPHCl5vKZ2vvgKg-1; Thu, 03 Dec 2020 12:12:03 -0500 X-MC-Unique: mzLNlnliPHCl5vKZ2vvgKg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 053AD805EE3; Thu, 3 Dec 2020 17:11:42 +0000 (UTC) Received: from localhost.localdomain (unknown [10.35.206.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6431F6085A; Thu, 3 Dec 2020 17:11:35 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: "H. Peter Anvin" , Paolo Bonzini , Jonathan Corbet , Jim Mattson , Wanpeng Li , linux-kselftest@vger.kernel.org (open list:KERNEL SELFTEST FRAMEWORK), Vitaly Kuznetsov , Marcelo Tosatti , Thomas Gleixner , Sean Christopherson , linux-kernel@vger.kernel.org (open list), Ingo Molnar , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), Joerg Roedel , Borislav Petkov , Shuah Khan , Maxim Levitsky , Andrew Jones , Oliver Upton , linux-doc@vger.kernel.org (open list:DOCUMENTATION) Subject: [PATCH v2 2/3] KVM: x86: introduce KVM_X86_QUIRK_TSC_HOST_ACCESS Date: Thu, 3 Dec 2020 19:11:17 +0200 Message-Id: <20201203171118.372391-3-mlevitsk@redhat.com> In-Reply-To: <20201203171118.372391-1-mlevitsk@redhat.com> References: <20201203171118.372391-1-mlevitsk@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This quirk reflects the fact that we currently treat MSR_IA32_TSC and MSR_TSC_ADJUST access by the host (e.g qemu) in a way that is different compared to an access from the guest. For host's MSR_IA32_TSC read we currently always return L1 TSC value, and for host's write we do the tsc synchronization. For host's MSR_TSC_ADJUST write, we don't make the tsc 'jump' as we should for this msr. When the hypervisor uses the new TSC GET/SET state ioctls, all of this is no longer needed, thus leave this enabled only with a quirk which the hypervisor can disable. Suggested-by: Paolo Bonzini Signed-off-by: Maxim Levitsky --- arch/x86/include/uapi/asm/kvm.h | 1 + arch/x86/kvm/x86.c | 19 ++++++++++++++----- 2 files changed, 15 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index 8e76d3701db3f..2a60fc6674164 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -404,6 +404,7 @@ struct kvm_sync_regs { #define KVM_X86_QUIRK_LAPIC_MMIO_HOLE (1 << 2) #define KVM_X86_QUIRK_OUT_7E_INC_RIP (1 << 3) #define KVM_X86_QUIRK_MISC_ENABLE_NO_MWAIT (1 << 4) +#define KVM_X86_QUIRK_TSC_HOST_ACCESS (1 << 5) #define KVM_STATE_NESTED_FORMAT_VMX 0 #define KVM_STATE_NESTED_FORMAT_SVM 1 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9b8a2fe3a2398..aabded17abae4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3091,7 +3091,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) break; case MSR_IA32_TSC_ADJUST: if (guest_cpuid_has(vcpu, X86_FEATURE_TSC_ADJUST)) { - if (!msr_info->host_initiated) { + if (!msr_info->host_initiated || + !kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_TSC_HOST_ACCESS)) { s64 adj = data - vcpu->arch.ia32_tsc_adjust_msr; adjust_tsc_offset_guest(vcpu, adj); } @@ -3118,7 +3119,8 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.msr_ia32_power_ctl = data; break; case MSR_IA32_TSC: - if (msr_info->host_initiated) { + if (msr_info->host_initiated && + kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_TSC_HOST_ACCESS)) { kvm_synchronize_tsc(vcpu, data); } else { u64 adj = kvm_compute_tsc_offset(vcpu, data) - vcpu->arch.l1_tsc_offset; @@ -3409,17 +3411,24 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vcpu->arch.msr_ia32_power_ctl; break; case MSR_IA32_TSC: { + u64 tsc_offset; + /* * Intel SDM states that MSR_IA32_TSC read adds the TSC offset * even when not intercepted. AMD manual doesn't explicitly * state this but appears to behave the same. * - * On userspace reads and writes, however, we unconditionally + * On userspace reads and writes, when KVM_X86_QUIRK_SPECIAL_TSC_READ + * is present, however, we unconditionally * return L1's TSC value to ensure backwards-compatible * behavior for migration. */ - u64 tsc_offset = msr_info->host_initiated ? vcpu->arch.l1_tsc_offset : - vcpu->arch.tsc_offset; + + if (msr_info->host_initiated && + kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_TSC_HOST_ACCESS)) + tsc_offset = vcpu->arch.l1_tsc_offset; + else + tsc_offset = vcpu->arch.tsc_offset; msr_info->data = kvm_scale_tsc(vcpu, rdtsc()) + tsc_offset; break;