From patchwork Mon Nov 27 03:43:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: EwanHai X-Patchwork-Id: 13469040 Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from mx1.zhaoxin.com (MX1.ZHAOXIN.COM [210.0.225.12]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5029EB for ; Sun, 26 Nov 2023 19:43:32 -0800 (PST) X-ASG-Debug-ID: 1701056607-086e236fef27ff0001-HEqcsx Received: from ZXSHMBX2.zhaoxin.com (ZXSHMBX2.zhaoxin.com [10.28.252.164]) by mx1.zhaoxin.com with ESMTP id NrY4m6C8f7h764DS (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Mon, 27 Nov 2023 11:43:27 +0800 (CST) X-Barracuda-Envelope-From: EwanHai-oc@zhaoxin.com X-Barracuda-RBL-Trusted-Forwarder: 10.28.252.164 Received: from zxbjmbx1.zhaoxin.com (10.29.252.163) by ZXSHMBX2.zhaoxin.com (10.28.252.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Mon, 27 Nov 2023 11:43:27 +0800 Received: from ewan-server.zhaoxin.com (10.28.66.55) by zxbjmbx1.zhaoxin.com (10.29.252.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Mon, 27 Nov 2023 11:43:26 +0800 X-Barracuda-RBL-Trusted-Forwarder: 10.28.252.164 From: EwanHai X-Barracuda-RBL-Trusted-Forwarder: 10.29.252.163 To: , , , CC: , , Subject: [PATCH v2] target/i386/kvm: Refine VMX controls setting for backward compatibility Date: Sun, 26 Nov 2023 22:43:26 -0500 X-ASG-Orig-Subj: [PATCH v2] target/i386/kvm: Refine VMX controls setting for backward compatibility Message-ID: <20231127034326.257596-1-ewanhai-oc@zhaoxin.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: zxbjmbx1.zhaoxin.com (10.29.252.163) To zxbjmbx1.zhaoxin.com (10.29.252.163) X-Barracuda-Connect: ZXSHMBX2.zhaoxin.com[10.28.252.164] X-Barracuda-Start-Time: 1701056607 X-Barracuda-Encrypted: ECDHE-RSA-AES128-GCM-SHA256 X-Barracuda-URL: https://10.28.252.35:4443/cgi-mod/mark.cgi X-Virus-Scanned: by bsmtpd at zhaoxin.com X-Barracuda-Scan-Msg-Size: 2739 X-Barracuda-BRTS-Status: 1 X-Barracuda-Bayes: INNOCENT GLOBAL 0.0000 1.0000 -2.0210 X-Barracuda-Spam-Score: -2.02 X-Barracuda-Spam-Status: No, SCORE=-2.02 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.3.117308 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Commit 4a910e1 ("target/i386: do not set unsupported VMX secondary execution controls") implemented a workaround for hosts that have specific CPUID features but do not support the corresponding VMX controls, e.g., hosts support RDSEED but do not support RDSEED-Exiting. In detail, commit 4a910e1 introduced a flag `has_msr_vmx_procbased_clts2`. If KVM has `MSR_IA32_VMX_PROCBASED_CTLS2` in its msr list, QEMU would use KVM's settings, avoiding any modifications to this MSR. However, this commit (4a910e1) didn't account for cases in older Linux kernels(<5.3) where `MSR_IA32_VMX_PROCBASED_CTLS2` is in `kvm_feature_msrs`-obtained by ioctl(KVM_GET_MSR_FEATURE_INDEX_LIST), but not in `kvm_msr_list`-obtained by ioctl(KVM_GET_MSR_INDEX_LIST). As a result,it did not set the `has_msr_vmx_procbased_clts2` flag based on `kvm_msr_list` alone, even though KVM maintains the value of this MSR. This patch supplements the above logic, ensuring that `has_msr_vmx_procbased_clts2` is correctly set by checking both MSR lists, thus maintaining compatibility with older kernels. Signed-off-by: EwanHai --- In response to the suggestions from ZhaoLiu(zhao1.liu@intel.com), the following changes have been implemented in v2: - Adjusted some punctuation in the commit message as per the suggestions. - Added comments to the newly added code to indicate that it is a compatibility fix. v1 link: https://lore.kernel.org/all/20230925071453.14908-1-ewanhai-oc@zhaoxin.com/ --- target/i386/kvm/kvm.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 11b8177eff..c8f6c0b531 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -2296,6 +2296,7 @@ void kvm_arch_do_init_vcpu(X86CPU *cpu) static int kvm_get_supported_feature_msrs(KVMState *s) { int ret = 0; + int i; if (kvm_feature_msrs != NULL) { return 0; @@ -2330,6 +2331,19 @@ static int kvm_get_supported_feature_msrs(KVMState *s) return ret; } + /* + * Compatibility fix: + * Older Linux kernels(<5.3) include the MSR_IA32_VMX_PROCBASED_CTLS2 + * only in feature msr list, but not in regular msr list. This lead to + * an issue in older kernel versions where QEMU, through the regular + * MSR list check, assumes the kernel doesn't maintain this msr, + * resulting in incorrect settings by QEMU for this msr. + */ + for (i = 0; i < kvm_feature_msrs->nmsrs; i++) { + if (kvm_feature_msrs->indices[i] == MSR_IA32_VMX_PROCBASED_CTLS2) { + has_msr_vmx_procbased_ctls2 = true; + } + } return 0; }