Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752887AbeADLtK (ORCPT + 1 other); Thu, 4 Jan 2018 06:49:10 -0500 Received: from smtp-fw-33001.amazon.com ([207.171.190.10]:6238 "EHLO smtp-fw-33001.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775AbeADLtJ (ORCPT ); Thu, 4 Jan 2018 06:49:09 -0500 X-Amazon-filename: smime.p7s X-IronPort-AV: E=Sophos;i="5.45,507,1508803200"; d="p7s'?scan'208";a="713352798" Message-ID: <1515066469.12987.112.camel@amazon.co.uk> Subject: Re: Avoid speculative indirect calls in kernel To: Pavel Machek CC: Paolo Bonzini , Alan Cox , Linus Torvalds , Andi Kleen , , Greg Kroah-Hartman , Tim Chen , "Linux Kernel Mailing List" , Dave Hansen In-Reply-To: <20180104114231.GB1702@amd> References: <20180103230934.15788-1-andi@firstfloor.org> <20180104114231.GB1702@amd> Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwBAMAAAClLOS0AAAAG1BMVEUHBwcUFBQpKSlGRkZhYWF9fX2Xl5eysrLMzMxFF+rXAAACaElEQVQ4y21UQXbbIBQE9wJALmAg6ToWON22FrhZthHgbvssUPathC7QWMful2JHSmtWwGg+zPxBCE0DU4QoJQgRgsg4w2gJjBNE8PjFBZgnQMBs+uZ1NQNQjZO3BV4AGDFC0f+l4DBG0VUAM4yv7SO8IgRdHXQ+A78HKL5OAeCfNQV5cHX8DsBUyIJKtYbt98BKaGNCKjfgFVkqYVLbkHKsRsbSCSa0T6npIqLrpRBgQKHUpQmgs9eEKaiUcooE8WWfCGVnBiUcn1uF2XhbfmN9apKnmMP2K4kizKkQWxuaVNOpU2cACIyxO1Po8ETHcXEDMVnozcejkAYA9iaD4pU0ZvNQ8VurNnTuFAYVtuIPUZW25PjDIjQAlGyffIiRQxoWAZBmJ0LTdW2Nyc0iP3DqRhxizvGJkBWZmyFVyZkddWzmBoIBVMpCCJ1CFzl98xav4VJKSSD45KbUT75ixikTphDSRh8+Uz7JLgUTAgAFwzqzjxc/nDY7WUApqY0OMdTwCKZSXplSKkgIRCHElCp8ZnhnKqXuwcNbk1L0VXE+I9alUXoHlLHl3mv7/dWQlJwtjREC7mu9L/U2jQyMUuO2EDS4q9Kl2ddm232bxIE5pjJuVwiljNn/Cfv25/T0cu5cZbwHGVq7h/zp0B4n3S99V/utD+Uo8BiGx9xCsOAV5z7/tjo4Z4z1Lvb90KZ7eFOoOeXOukqF2seo234YYuaQPpRP+cVZU5adT1Edun5Iz3z8fTz3+eSDh0Ip1c7zx1MaijGzTd/3MbRuBHz8cvcVgCMBRpOHvgu59WDhoat+nIZm+LWm9C/aaaGq5DCP9QAAAABJRU5ErkJggg== Organization: Amazon Content-Type: multipart/signed; micalg=sha-256; protocol="application/x-pkcs7-signature"; boundary="=-SYOHSjYbvk4qWKQUxiC2" Date: Thu, 4 Jan 2018 11:47:49 +0000 X-Mailer: Evolution 3.18.5.2-0ubuntu3.2 MIME-Version: 1.0 From: "Woodhouse, David" X-Evolution-Source: 1481217574.17989.4@uc8d3ff76b9bc5848a9cc Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: --=-SYOHSjYbvk4qWKQUxiC2 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2018-01-04 at 12:42 +0100, Pavel Machek wrote: >=20 > > No, really. The full mitigation with the microcode update and IBRS > > support is *slow*. Horribly slow. >=20 > What is IBRS? Invalidate BRanch prediction bufferS? That isn't the precise acronym, but yes. The branch predictor flush that, without retpoline, we have to do on every entry to the kernel. Requires new microcode, and the patches that I believe Intel are *about* to post... The first variant (all they can do on current CPUs with a microcode update) is really slow, and thus retpoline is *very* much the preferred option to protect the kernel on current CPUs. Later CPUs will apparently have a better version of IBRS which is preferred, so we'll ALTERNATIVE out the retpoline if we discover we're running on one of those. Public docs will, presumably, be forthcoming Real Soon Now=E2=84=A2. --=-SYOHSjYbvk4qWKQUxiC2 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 VMEYPfqDt/65xoc6Tdih+qkY2pNDppZ1DZ8mVrAX6O2O60ZhmXB60wMoDvXPZInvkMOW4drqnje/ 7/NOypn/XQAY+ln4KT+3tHG3TfryyJFMedqC/r29KJlCeeCxIzdtq2j5mN42tvPVv4+p+Kr77uui GOASNdFJbNdgx7UGF+il6kRGSle17LJZKMgRiLJXYjECwnGwdfLdN5SINWD5IC3yXY8d14Bq6DyD jNts1DFw+SKhW8kVFYRZpv7TE3/42QJKQVL6YWka5T4EJO7AD3gy2ypRsd8CAwEAAaOCAecwggHj MB8GA1UdIwQYMBaAFIKvbIz4xf6WYXzoHz0rcUhexIvAMB0GA1UdDgQWBBT/vhvBExl2wDr8f50u b+0yzFyZRjAOBgNVHQ8BAf8EBAMCBaAwDAYDVR0TAQH/BAIwADAgBgNVHSUEGTAXBggrBgEFBQcD BAYLKwYBBAGyMQEDBQIwEQYJYIZIAYb4QgEBBAQDAgUgMEYGA1UdIAQ/MD0wOwYMKwYBBAGyMQEC AQEBMCswKQYIKwYBBQUHAgEWHWh0dHBzOi8vc2VjdXJlLmNvbW9kby5uZXQvQ1BTMFoGA1UdHwRT MFEwT6BNoEuGSWh0dHA6Ly9jcmwuY29tb2RvY2EuY29tL0NPTU9ET1JTQUNsaWVudEF1dGhlbnRp Y2F0aW9uYW5kU2VjdXJlRW1haWxDQS5jcmwwgYsGCCsGAQUFBwEBBH8wfTBVBggrBgEFBQcwAoZJ aHR0cDovL2NydC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRT ZWN1cmVFbWFpbENBLmNydDAkBggrBgEFBQcwAYYYaHR0cDovL29jc3AuY29tb2RvY2EuY29tMBwG A1UdEQQVMBOBEWR3bXdAYW1hem9uLmNvLnVrMA0GCSqGSIb3DQEBCwUAA4IBAQCK2HofespbCaDu udwwfh8GxDpVUnVbZZVWScpZMxfYpXzLot7L6iZrr16oMQ+UOiDDAK6/D3+u2QN8u0lJ6yLKVmvh lGOzDywGsyG2Ohy8Dt5jcEK5sz84OsPtrRH7ahZHLxYPhWlUKOjOPN6sb9h6uMYlXmG/KmAr2rwF exN6Zrwh6YwF7ukuMs175YcNyYRdB8kVYq3WikfbTHOoRbJiu9Unw7LqnvPTfx+xUvD6aN2CKLtr mactWbk98swNgbI18UWjfEpugvAqw09CDLjeq7N1v0SkUkQEDqGSUE+hKFryTNXtZ6zOfl+MQfD8 U7T5oJa34DmWXK9+x7dl+MrqMIIFLjCCBBagAwIBAgIRAKRLS99YOh+0Tl3TokJwPUYwDQYJKoZI hvcNAQELBQAwgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVyIE1hbmNoZXN0ZXIxEDAO BgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMT0wOwYDVQQDEzRDT01P RE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJlIEVtYWlsIENBMB4XDTE3MTIy MTAwMDAwMFoXDTE4MTIyMTIzNTk1OVowIjEgMB4GCSqGSIb3DQEJARYRZHdtd0BhbWF6b24uY28u dWswggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQCnRioF7sCjINq/ov+AWWQtHXUcTat8 SCk2pInv1Qks6Duz9ewN+mc1HFTBGD36g7f+ucaHOk3YofqpGNqTQ6aWdQ2fJlawF+jtjutGYZlw etMDKA71z2SJ75DDluHa6p43v+/zTsqZ/10AGPpZ+Ck/t7Rxt0368siRTHnagv69vSiZQnngsSM3 bato+ZjeNrbz1b+Pqfiq++7rohjgEjXRSWzXYMe1BhfopepERkpXteyyWSjIEYiyV2IxAsJxsHXy 3TeUiDVg+SAt8l2PHdeAaug8g4zbbNQxcPkioVvJFRWEWab+0xN/+NkCSkFS+mFpGuU+BCTuwA94 MtsqUbHfAgMBAAGjggHnMIIB4zAfBgNVHSMEGDAWgBSCr2yM+MX+lmF86B89K3FIXsSLwDAdBgNV HQ4EFgQU/74bwRMZdsA6/H+dLm/tMsxcmUYwDgYDVR0PAQH/BAQDAgWgMAwGA1UdEwEB/wQCMAAw IAYDVR0lBBkwFwYIKwYBBQUHAwQGCysGAQQBsjEBAwUCMBEGCWCGSAGG+EIBAQQEAwIFIDBGBgNV HSAEPzA9MDsGDCsGAQQBsjEBAgEBATArMCkGCCsGAQUFBwIBFh1odHRwczovL3NlY3VyZS5jb21v ZG8ubmV0L0NQUzBaBgNVHR8EUzBRME+gTaBLhklodHRwOi8vY3JsLmNvbW9kb2NhLmNvbS9DT01P RE9SU0FDbGllbnRBdXRoZW50aWNhdGlvbmFuZFNlY3VyZUVtYWlsQ0EuY3JsMIGLBggrBgEFBQcB AQR/MH0wVQYIKwYBBQUHMAKGSWh0dHA6Ly9jcnQuY29tb2RvY2EuY29tL0NPTU9ET1JTQUNsaWVu dEF1dGhlbnRpY2F0aW9uYW5kU2VjdXJlRW1haWxDQS5jcnQwJAYIKwYBBQUHMAGGGGh0dHA6Ly9v Y3NwLmNvbW9kb2NhLmNvbTAcBgNVHREEFTATgRFkd213QGFtYXpvbi5jby51azANBgkqhkiG9w0B AQsFAAOCAQEAith6H3rKWwmg7rncMH4fBsQ6VVJ1W2WVVknKWTMX2KV8y6Ley+oma69eqDEPlDog wwCuvw9/rtkDfLtJSesiylZr4ZRjsw8sBrMhtjocvA7eY3BCubM/ODrD7a0R+2oWRy8WD4VpVCjo zjzerG/YerjGJV5hvypgK9q8BXsTema8IemMBe7pLjLNe+WHDcmEXQfJFWKt1opH20xzqEWyYrvV J8Oy6p7z038fsVLw+mjdgii7a5mnLVm5PfLMDYGyNfFFo3xKboLwKsNPQgy43quzdb9EpFJEBA6h klBPoSha8kzV7Weszn5fjEHw/FO0+aCWt+A5llyvfse3ZfjK6jCCBeYwggPOoAMCAQICEGqb4Tg7 /ytrnwHV2binUlYwDQYJKoZIhvcNAQEMBQAwgYUxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVh dGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1p dGVkMSswKQYDVQQDEyJDT01PRE8gUlNBIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTEzMDEx MDAwMDAwMFoXDTI4MDEwOTIzNTk1OVowgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVhdGVy IE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVk MT0wOwYDVQQDEzRDT01PRE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJlIEVt YWlsIENBMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvrOeV6wodnVAFsc4A5jTxhh2 IVDzJXkLTLWg0X06WD6cpzEup/Y0dtmEatrQPTRI5Or1u6zf+bGBSyD9aH95dDSmeny1nxdlYCeX IoymMv6pQHJGNcIDpFDIMypVpVSRsivlJTRENf+RKwrB6vcfWlP8dSsE3Rfywq09N0ZfxcBa39V0 wsGtkGWC+eQKiz4pBZYKjrc5NOpG9qrxpZxyb4o4yNNwTqzaaPpGRqXB7IMjtf7tTmU2jqPMLxFN e1VXj9XB1rHvbRikw8lBoNoSWY66nJN/VCJv5ym6Q0mdCbDKCMPybTjoNCQuelc0IAaO4nLUXk0B OSxSxt8kCvsUtQIDAQABo4IBPDCCATgwHwYDVR0jBBgwFoAUu69+Aj36pvE8hI6t7jiY7NkyMtQw HQYDVR0OBBYEFIKvbIz4xf6WYXzoHz0rcUhexIvAMA4GA1UdDwEB/wQEAwIBhjASBgNVHRMBAf8E CDAGAQH/AgEAMBEGA1UdIAQKMAgwBgYEVR0gADBMBgNVHR8ERTBDMEGgP6A9hjtodHRwOi8vY3Js LmNvbW9kb2NhLmNvbS9DT01PRE9SU0FDZXJ0aWZpY2F0aW9uQXV0aG9yaXR5LmNybDBxBggrBgEF BQcBAQRlMGMwOwYIKwYBBQUHMAKGL2h0dHA6Ly9jcnQuY29tb2RvY2EuY29tL0NPTU9ET1JTQUFk ZFRydXN0Q0EuY3J0MCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5jb21vZG9jYS5jb20wDQYJKoZI hvcNAQEMBQADggIBAHhcsoEoNE887l9Wzp+XVuyPomsX9vP2SQgG1NgvNc3fQP7TcePo7EIMERoh 42awGGsma65u/ITse2hKZHzT0CBxhuhb6txM1n/y78e/4ZOs0j8CGpfb+SJA3GaBQ+394k+z3ZBy WPQedXLL1OdK8aRINTsjk/H5Ns77zwbjOKkDamxlpZ4TKSDMKVmU/PUWNMKSTvtlenlxBhh7ETrN 543j/Q6qqgCWgWuMAXijnRglp9fyadqGOncjZjaaSOGTTFB+E2pvOUtY+hPebuPtTbq7vODqzCM6 ryEhNhzf+enm0zlpXK7q332nXttNtjv7VFNYG+I31gnMrwfHM5tdhYF/8v5UY5g2xANPECTQdu9v WPoqNSGDt87b3gXb1AiGGaI06vzgkejL580ul+9hz9D0S0U4jkhJiA7EuTecP/CFtR72uYRBcunw wH3fciPjviDDAI9SnC/2aPY8ydehzuZutLbZdRJ5PDEJM/1tyZR2niOYihZ+FCbtf3D9mB12D4ln 9icgc7CwaxpNSCPt8i/GqK2HsOgkL3VYnwtx7cJUmpvVdZ4ognzgXtgtdk3ShrtOS1iAN2ZBXFiR mjVzmehoMof06r1xub+85hFQzVxZx5/bRaTKTlL8YXLI8nAbR9HWdFqzcOoB/hxfEyIQpx9/s81r gzdEZOofSlZHynoSMYIDyjCCA8YCAQEwga0wgZcxCzAJBgNVBAYTAkdCMRswGQYDVQQIExJHcmVh dGVyIE1hbmNoZXN0ZXIxEDAOBgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1p dGVkMT0wOwYDVQQDEzRDT01PRE8gUlNBIENsaWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJl IEVtYWlsIENBAhEApEtL31g6H7ROXdOiQnA9RjANBglghkgBZQMEAgEFAKCCAe0wGAYJKoZIhvcN AQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTgwMTA0MTE0NzQ5WjAvBgkqhkiG9w0B CQQxIgQg92cBj8KimQNzp8vBaSIDPvr4XrpLl7sI7Nzq1HP5gagwgb4GCSsGAQQBgjcQBDGBsDCB rTCBlzELMAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMH U2FsZm9yZDEaMBgGA1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0Eg Q2xpZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEQCkS0vfWDoftE5d06JC cD1GMIHABgsqhkiG9w0BCRACCzGBsKCBrTCBlzELMAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0 ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMRQ09NT0RPIENBIExpbWl0 ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0aW9uIGFuZCBTZWN1cmUg RW1haWwgQ0ECEQCkS0vfWDoftE5d06JCcD1GMA0GCSqGSIb3DQEBAQUABIIBAHctUKw50f38enaG vzsUHS7L7WmSUfLarNqPLxfvGUt7cGQe92RNMPXIv73ZaYYrRUujsTvHmgcVcK8i5qs5Uf8Hj1AO qV06+FHWC7jDnjYqaoLh0DlMIfbCXqDFHfG5CLiRl5i9Qqr6Zzblb29lCs0Jw6o+BMAp4CCWUsTL wbV/cvzTVQUnCbyF1PSCqhjuT/32SK5atIMaW1VAxX6EU0FCMDRWtsp74qUBtDgPn4428Ptjt6zp vG6ezlcfsW+iTPk/vyMhg3b9oKOib3OXCwW3PRnNBnCqA9//T8hL27bfh9K/H5pk3/dOMyjn+6Am jOFQuF4u3UlaHMEwZPXGRPkAAAAAAAA= --=-SYOHSjYbvk4qWKQUxiC2--