From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227byjsD7EthkUmTWIj1QhXRwtzJxm/5zE3kp0fC7zXathMXrTH39PcvNnkC2l286mPVL4Ki ARC-Seal: i=1; a=rsa-sha256; t=1517433474; cv=none; d=google.com; s=arc-20160816; b=sVvlz+OC031AcfQeFurwE40vE+BI0UpZytjCOtqu5Jrn4LnEUaaqC8qwEjlWBCLhfY 0rhBq0GIbvuxFlO+KC/XGKAbUadvBgor8E2hYbLZZviJsY4oICjijLgFi3UfTwsdqtQv scfABJomvJZ4HQsUPO7oNHhIqgVmog4z/1/6+RirtiRJhNfr6fpFQpM+ZBJdxvqVqJ5p LgVAsts4pmwHzBdauuhx9pMw5acOyW1It7ozLmCjSZtG2DCWge20aXvHWEVn0cO4TMb0 MCDY7WZKqj3Qx6DsLjGlS+rUEZR2SdKf+pqxOIFDIrY9LKpfNjlDZR3H22Vox+cCcdn7 xKKA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=precedence:mime-version:accept-language:in-reply-to:references :message-id:date:thread-index:thread-topic:subject:cc:to:from :mime-version:dkim-signature:arc-authentication-results; bh=N3i3eMjfI7TvF+WBh9NJ7uOfBLnHAzeD4Th3Md0SVXY=; b=oZ5m6+lg/JRgl0l+8wz76f5YuCGKpd2wg9egWrrEqjs4AdXN+R5rROG+j0QCbm6YQ+ zD98Qm6m0pbt6wpod800G0/8aRzdjeHp9xdPVuQOh2ySMi/R1GzmEfLtyQKpAGwwH4o4 LR2bB5gZuev3bEW13r1kNBo56FmnKezK5G0kkGQtR64XtrLvO8F/REewhZI7IUh0pl+H /0J8J+mg5yYvK18SY/zwXl1Y+7pQJXC0KTQRI/bFS3NrA7iAd2VNoZp2b1H2EV5mL9SW HOevYTN2WmUACoG568CwrPTKABh/dZLM3eZhijVyIAEuwYAoSiucWW5K9e0Xt7GO5rYp VogQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@amazon.co.uk header.s=amazon201209 header.b=aO2bGQZn; spf=pass (google.com: domain of prvs=56249cc1e=dwmw@amazon.co.uk designates 52.95.49.90 as permitted sender) smtp.mailfrom=prvs=56249cc1e=dwmw@amazon.co.uk; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amazon.co.uk Authentication-Results: mx.google.com; dkim=pass header.i=@amazon.co.uk header.s=amazon201209 header.b=aO2bGQZn; spf=pass (google.com: domain of prvs=56249cc1e=dwmw@amazon.co.uk designates 52.95.49.90 as permitted sender) smtp.mailfrom=prvs=56249cc1e=dwmw@amazon.co.uk; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amazon.co.uk X-Amazon-filename: smime.p7s X-IronPort-AV: E=Sophos;i="5.46,441,1511827200"; d="p7s'?scan'208";a="330033448" Content-Type: multipart/mixed; boundary="===============6724934174547643374==" MIME-Version: 1.0 From: "Woodhouse, David" To: "jmattson@google.com" , "pbonzini@redhat.com" CC: "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "arjan.van.de.ven@intel.com" , "ashok.raj@intel.com" , "Raslan, KarimAllah" , "Raslan, KarimAllah" , "torvalds@linux-foundation.org" , "tglx@linutronix.de" , "tim.c.chen@linux.intel.com" , "ak@linux.intel.com" , "x86@kernel.org" , "dan.j.williams@intel.com" , "aarcange@redhat.com" , "luto@kernel.org" , "gregkh@linuxfoundation.org" , "dave.hansen@intel.com" , "asit.k.mallick@intel.com" , "jun.nakajima@intel.com" Subject: Re: [PATCH v5 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL Thread-Topic: [PATCH v5 4/5] KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL Thread-Index: AQHTmssLrcqA5PzFukaHupAPK3+9WKOOZNkAgAACJoCAAATKAIAABIGAgAAFZgCAAAHXgIAAAWIAgAADYIA= Date: Wed, 31 Jan 2018 21:17:46 +0000 Message-ID: <1517433465.18619.209.camel@amazon.co.uk> References: <1517427467-28567-1-git-send-email-karahmed@amazon.de> <1517427467-28567-5-git-send-email-karahmed@amazon.de> <06cb88da-f355-41ed-380f-7daa8ddf6159@amazon.com> <67dca2bb-1298-c7fa-f681-018e4edc6725@redhat.com> <16d89e09-fbfc-4a08-00a6-40cfb4776018@redhat.com> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: yes X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.43.60.116] MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591113692084885209?= X-GMAIL-MSGID: =?utf-8?q?1591144322618484641?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: --===============6724934174547643374== Content-Language: en-US Content-Type: multipart/signed; micalg=sha-256; protocol="application/x-pkcs7-signature"; boundary="=-gJf04PP6HFULl0xoPmKi" --=-gJf04PP6HFULl0xoPmKi Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2018-01-31 at 13:05 -0800, Jim Mattson wrote: > On Wed, Jan 31, 2018 at 1:00 PM, Paolo Bonzini wrot= e: >=20 > > Yes, but how would moving the field into struct loaded_vmcs do anything= ? > >=C2=A0 Only vmon/vmoff would change anything in vmx->nested.vmcs02. >=20 > My suggestion was that nested_vmx_merge_msr_bitmap should set the > vmcs02 version of save_spec_ctrl_on_exit based on the calculated value > of the write permission bit for IA32_SPEC_CTRL in the vmcs02 MSR > permission bitmap. >=20 > > Even then, L1 vmexits will also be penalized because L1 has probably > > done an RDMSR/WRMSR on L2->L1 vmexit.=C2=A0 So I don't think it's an is= sue? >=20 > Yes, it sucks to be L1 in this situation. Well... we *could* clear the save_spec_ctrl_on_exit flag and intercept the MSR again, any time that the actual value of spec_ctrl is zero.=C2=A0 I don't think we'd want to do that too aggressively, but there might be something we could do there. --=-gJf04PP6HFULl0xoPmKi Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCEE4w ggUuMIIEFqADAgECAhEApEtL31g6H7ROXdOiQnA9RjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTcxMjIxMDAwMDAwWhcNMTgxMjIxMjM1 OTU5WjAiMSAwHgYJKoZIhvcNAQkBFhFkd213QGFtYXpvbi5jby51azCCASIwDQYJKoZIhvcNAQEB BQADggEPADCCAQoCggEBAKdGKgXuwKMg2r+i/4BZZC0ddRxNq3xIKTakie/VCSzoO7P17A36ZzUc 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