From patchwork Fri Jul 5 21:06:36 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liran Alon X-Patchwork-Id: 11033343 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 42F9E912 for ; Fri, 5 Jul 2019 21:07:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 34052288F8 for ; Fri, 5 Jul 2019 21:07:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2856628B0C; Fri, 5 Jul 2019 21:07:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7A29C28B18 for ; Fri, 5 Jul 2019 21:07:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727982AbfGEVH3 (ORCPT ); Fri, 5 Jul 2019 17:07:29 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:42964 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727914AbfGEVH2 (ORCPT ); Fri, 5 Jul 2019 17:07:28 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x65L3ssF119898; Fri, 5 Jul 2019 21:07:06 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=corp-2018-07-02; bh=c1/s290z5etu0n2dhhW4gTKM/KYEKjonva5/EhYLZIU=; b=GqFIVJ+LGAkA/7QG8/2sY22kgXgTR/GX92pg2il3KbclJ+vyFhXi/+Zfq4oOUetdGzgE 4OprN6smZGcLb1oNPgc2Ifw91FO98/IQNY8A5i0xe6rx/eNuK3dK3TuRCRe+CQTmjf4j LRTqIYEhpHccp5jw+jJxPU0jXg00+KihuiKMIpMAGmCgKiJCtRaUfAyp3vAUjXfIs6wZ FORMAdyeYecRlaSMH2yHP9PCcAEhbs6mZHooThE99+uzwKTWFgo1XXDeHLp2/0vkj7QC VKSejnb9wqeTmt0g9Sp3soj67dVJPeERAbfdVycDDEPjSQRd1PA/r+Xf8/5BPlJa2bIR eQ== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2te61emgg7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Jul 2019 21:07:06 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x65L2X1w107403; Fri, 5 Jul 2019 21:07:05 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 2thxrvm49m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 05 Jul 2019 21:07:05 +0000 Received: from abhmp0003.oracle.com (abhmp0003.oracle.com [141.146.116.9]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x65L744d030880; Fri, 5 Jul 2019 21:07:04 GMT Received: from spark.ravello.local (/213.57.127.2) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 05 Jul 2019 14:07:04 -0700 From: Liran Alon To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com, ehabkost@redhat.com, kvm@vger.kernel.org, Liran Alon , Joao Martins Subject: [PATCH 4/4] target/i386: kvm: Demand nested migration kernel capabilities only when vCPU may have enabled VMX Date: Sat, 6 Jul 2019 00:06:36 +0300 Message-Id: <20190705210636.3095-5-liran.alon@oracle.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190705210636.3095-1-liran.alon@oracle.com> References: <20190705210636.3095-1-liran.alon@oracle.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9309 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=3 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907050266 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9309 signatures=668688 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907050266 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Previous to this change, a vCPU exposed with VMX running on a kernel without KVM_CAP_NESTED_STATE or KVM_CAP_EXCEPTION_PAYLOAD resulted in adding a migration blocker. This was because when code was written it was thought there is no way to reliabely know if a vCPU is utilising VMX or not at runtime. However, it turns out that this can be known to some extent: In order for a vCPU to enter VMX operation it must have CR4.VMXE set. Since it was set, CR4.VMXE must remain set as long as vCPU is in VMX operation. This is because CR4.VMXE is one of the bits set in MSR_IA32_VMX_CR4_FIXED1. There is one exception to above statement when vCPU enters SMM mode. When a vCPU enters SMM mode, it temporarily exit VMX operation and may also reset CR4.VMXE during execution in SMM mode. When vCPU exits SMM mode, vCPU state is restored to be in VMX operation and CR4.VMXE is restored to it's original value of being set. Therefore, when vCPU is not in SMM mode, we can infer whether VMX is being used by examining CR4.VMXE. Otherwise, we cannot know for certain but assume the worse that vCPU may utilise VMX. Summaring all the above, a vCPU may have enabled VMX in case CR4.VMXE is set or vCPU is in SMM mode. Therefore, remove migration blocker and check before migration (cpu_pre_save()) if vCPU may have enabled VMX. If true, only then require relevant kernel capabilities. While at it, demand KVM_CAP_EXCEPTION_PAYLOAD only when vCPU is in guest-mode and there is a pending/injected exception. Otherwise, this kernel capability is not required for proper migration. Reviewed-by: Joao Martins Signed-off-by: Liran Alon Reviewed-by: Maran Wilson Tested-by: Maran Wilson --- target/i386/cpu.h | 22 ++++++++++++++++++++++ target/i386/kvm.c | 26 ++++++-------------------- target/i386/kvm_i386.h | 1 + target/i386/machine.c | 24 ++++++++++++++++++++---- 4 files changed, 49 insertions(+), 24 deletions(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index cdb0e43676a9..c752c4d936ee 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1872,6 +1872,28 @@ static inline bool cpu_has_svm(CPUX86State *env) return env->features[FEAT_8000_0001_ECX] & CPUID_EXT3_SVM; } +/* + * In order for a vCPU to enter VMX operation it must have CR4.VMXE set. + * Since it was set, CR4.VMXE must remain set as long as vCPU is in + * VMX operation. This is because CR4.VMXE is one of the bits set + * in MSR_IA32_VMX_CR4_FIXED1. + * + * There is one exception to above statement when vCPU enters SMM mode. + * When a vCPU enters SMM mode, it temporarily exit VMX operation and + * may also reset CR4.VMXE during execution in SMM mode. + * When vCPU exits SMM mode, vCPU state is restored to be in VMX operation + * and CR4.VMXE is restored to it's original value of being set. + * + * Therefore, when vCPU is not in SMM mode, we can infer whether + * VMX is being used by examining CR4.VMXE. Otherwise, we cannot + * know for certain. + */ +static inline bool cpu_vmx_maybe_enabled(CPUX86State *env) +{ + return cpu_has_vmx(env) && + ((env->cr[4] & CR4_VMXE_MASK) || (env->hflags & HF_SMM_MASK)); +} + /* fpu_helper.c */ void update_fp_status(CPUX86State *env); void update_mxcsr_status(CPUX86State *env); diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 4e2c8652168f..d3af445eeb5d 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -128,6 +128,11 @@ bool kvm_has_adjust_clock_stable(void) return (ret == KVM_CLOCK_TSC_STABLE); } +bool kvm_has_exception_payload(void) +{ + return has_exception_payload; +} + bool kvm_allows_irq0_override(void) { return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing(); @@ -1341,7 +1346,6 @@ static int hyperv_init_vcpu(X86CPU *cpu) } static Error *invtsc_mig_blocker; -static Error *nested_virt_mig_blocker; #define KVM_MAX_CPUID_ENTRIES 100 @@ -1640,22 +1644,6 @@ int kvm_arch_init_vcpu(CPUState *cs) !!(c->ecx & CPUID_EXT_SMX); } - if (cpu_has_vmx(env) && !nested_virt_mig_blocker && - ((kvm_max_nested_state_length() <= 0) || !has_exception_payload)) { - error_setg(&nested_virt_mig_blocker, - "Kernel do not provide required capabilities for " - "nested virtualization migration. " - "(CAP_NESTED_STATE=%d, CAP_EXCEPTION_PAYLOAD=%d)", - kvm_max_nested_state_length() > 0, - has_exception_payload); - r = migrate_add_blocker(nested_virt_mig_blocker, &local_err); - if (local_err) { - error_report_err(local_err); - error_free(nested_virt_mig_blocker); - return r; - } - } - if (env->mcg_cap & MCG_LMCE_P) { has_msr_mcg_ext_ctl = has_msr_feature_control = true; } @@ -1670,7 +1658,7 @@ int kvm_arch_init_vcpu(CPUState *cs) if (local_err) { error_report_err(local_err); error_free(invtsc_mig_blocker); - goto fail2; + return r; } } } @@ -1741,8 +1729,6 @@ int kvm_arch_init_vcpu(CPUState *cs) fail: migrate_del_blocker(invtsc_mig_blocker); - fail2: - migrate_del_blocker(nested_virt_mig_blocker); return r; } diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h index 3057ba4f7d19..06fe06bdb3d6 100644 --- a/target/i386/kvm_i386.h +++ b/target/i386/kvm_i386.h @@ -35,6 +35,7 @@ bool kvm_allows_irq0_override(void); bool kvm_has_smm(void); bool kvm_has_adjust_clock_stable(void); +bool kvm_has_exception_payload(void); void kvm_synchronize_all_tsc(void); void kvm_arch_reset_vcpu(X86CPU *cs); void kvm_arch_do_init_vcpu(X86CPU *cs); diff --git a/target/i386/machine.c b/target/i386/machine.c index 20bda9f80154..c04021937722 100644 --- a/target/i386/machine.c +++ b/target/i386/machine.c @@ -7,6 +7,7 @@ #include "hw/isa/isa.h" #include "migration/cpu.h" #include "hyperv.h" +#include "kvm_i386.h" #include "sysemu/kvm.h" #include "sysemu/tcg.h" @@ -232,10 +233,25 @@ static int cpu_pre_save(void *opaque) } #ifdef CONFIG_KVM - /* Verify we have nested virtualization state from kernel if required */ - if (kvm_enabled() && cpu_has_vmx(env) && !env->nested_state) { - error_report("Guest enabled nested virtualization but kernel " - "does not support saving of nested state"); + /* + * In case vCPU may have enabled VMX, we need to make sure kernel have + * required capabilities in order to perform migration correctly: + * + * 1) We must be able to extract vCPU nested-state from KVM. + * + * 2) In case vCPU is running in guest-mode and it has a pending exception, + * we must be able to determine if it's in a pending or injected state. + * Note that in case KVM don't have required capability to do so, + * a pending/injected exception will always appear as an + * injected exception. + */ + if (kvm_enabled() && cpu_vmx_maybe_enabled(env) && + (!env->nested_state || + (!kvm_has_exception_payload() && (env->hflags & HF_GUEST_MASK) && + env->exception_injected))) { + error_report("Guest maybe enabled nested virtualization but kernel " + "does not support required capabilities to save vCPU " + "nested state"); return -EINVAL; } #endif