From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 C82A5C10F11 for ; Wed, 24 Apr 2019 14:29:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DED120811 for ; Wed, 24 Apr 2019 14:29:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730609AbfDXO3a (ORCPT ); Wed, 24 Apr 2019 10:29:30 -0400 Received: from foss.arm.com ([217.140.101.70]:44926 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726272AbfDXO33 (ORCPT ); Wed, 24 Apr 2019 10:29:29 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4F39D80D; Wed, 24 Apr 2019 07:29:29 -0700 (PDT) Received: from [10.1.196.92] (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B526D3F5AF; Wed, 24 Apr 2019 07:29:27 -0700 (PDT) Subject: Re: [PATCH v10 2/5] KVM: arm/arm64: context-switch ptrauth registers To: Dave Martin , Amit Daniel Kachhap Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , Kristina Martsenko , kvmarm@lists.cs.columbia.edu, Ramana Radhakrishnan , linux-kernel@vger.kernel.org References: <1555994558-26349-1-git-send-email-amit.kachhap@arm.com> <1555994558-26349-3-git-send-email-amit.kachhap@arm.com> <20190424133903.GU3567@e103592.cambridge.arm.com> From: Marc Zyngier Openpgp: preference=signencrypt Autocrypt: addr=marc.zyngier@arm.com; prefer-encrypt=mutual; keydata= mQINBE6Jf0UBEADLCxpix34Ch3kQKA9SNlVQroj9aHAEzzl0+V8jrvT9a9GkK+FjBOIQz4KE g+3p+lqgJH4NfwPm9H5I5e3wa+Scz9wAqWLTT772Rqb6hf6kx0kKd0P2jGv79qXSmwru28vJ t9NNsmIhEYwS5eTfCbsZZDCnR31J6qxozsDHpCGLHlYym/VbC199Uq/pN5gH+5JHZyhyZiNW ozUCjMqC4eNW42nYVKZQfbj/k4W9xFfudFaFEhAf/Vb1r6F05eBP1uopuzNkAN7vqS8XcgQH qXI357YC4ToCbmqLue4HK9+2mtf7MTdHZYGZ939OfTlOGuxFW+bhtPQzsHiW7eNe0ew0+LaL 3wdNzT5abPBscqXWVGsZWCAzBmrZato+Pd2bSCDPLInZV0j+rjt7MWiSxEAEowue3IcZA++7 ifTDIscQdpeKT8hcL+9eHLgoSDH62SlubO/y8bB1hV8JjLW/jQpLnae0oz25h39ij4ijcp8N t5slf5DNRi1NLz5+iaaLg4gaM3ywVK2VEKdBTg+JTg3dfrb3DH7ctTQquyKun9IVY8AsxMc6 lxl4HxrpLX7HgF10685GG5fFla7R1RUnW5svgQhz6YVU33yJjk5lIIrrxKI/wLlhn066mtu1 DoD9TEAjwOmpa6ofV6rHeBPehUwMZEsLqlKfLsl0PpsJwov8TQARAQABtCNNYXJjIFp5bmdp ZXIgPG1hcmMuenluZ2llckBhcm0uY29tPokCOwQTAQIAJQIbAwYLCQgHAwIGFQgCCQoLBBYC AwECHgECF4AFAk6NvYYCGQEACgkQI9DQutE9ekObww/+NcUATWXOcnoPflpYG43GZ0XjQLng LQFjBZL+CJV5+1XMDfz4ATH37cR+8gMO1UwmWPv5tOMKLHhw6uLxGG4upPAm0qxjRA/SE3LC 22kBjWiSMrkQgv5FDcwdhAcj8A+gKgcXBeyXsGBXLjo5UQOGvPTQXcqNXB9A3ZZN9vS6QUYN TXFjnUnzCJd+PVI/4jORz9EUVw1q/+kZgmA8/GhfPH3xNetTGLyJCJcQ86acom2liLZZX4+1 6Hda2x3hxpoQo7pTu+XA2YC4XyUstNDYIsE4F4NVHGi88a3N8yWE+Z7cBI2HjGvpfNxZnmKX 6bws6RQ4LHDPhy0yzWFowJXGTqM/e79c1UeqOVxKGFF3VhJJu1nMlh+5hnW4glXOoy/WmDEM UMbl9KbJUfo+GgIQGMp8mwgW0vK4HrSmevlDeMcrLdfbbFbcZLNeFFBn6KqxFZaTd+LpylIH bOPN6fy1Dxf7UZscogYw5Pt0JscgpciuO3DAZo3eXz6ffj2NrWchnbj+SpPBiH4srfFmHY+Y LBemIIOmSqIsjoSRjNEZeEObkshDVG5NncJzbAQY+V3Q3yo9og/8ZiaulVWDbcpKyUpzt7pv cdnY3baDE8ate/cymFP5jGJK++QCeA6u6JzBp7HnKbngqWa6g8qDSjPXBPCLmmRWbc5j0lvA 6ilrF8m5Ag0ETol/RQEQAM/2pdLYCWmf3rtIiP8Wj5NwyjSL6/UrChXtoX9wlY8a4h3EX6E3 64snIJVMLbyr4bwdmPKULlny7T/R8dx/mCOWu/DztrVNQiXWOTKJnd/2iQblBT+W5W8ep/nS w3qUIckKwKdplQtzSKeE+PJ+GMS+DoNDDkcrVjUnsoCEr0aK3cO6g5hLGu8IBbC1CJYSpple VVb/sADnWF3SfUvJ/l4K8Uk4B4+X90KpA7U9MhvDTCy5mJGaTsFqDLpnqp/yqaT2P7kyMG2E w+eqtVIqwwweZA0S+tuqput5xdNAcsj2PugVx9tlw/LJo39nh8NrMxAhv5aQ+JJ2I8UTiHLX QvoC0Yc/jZX/JRB5r4x4IhK34Mv5TiH/gFfZbwxd287Y1jOaD9lhnke1SX5MXF7eCT3cgyB+ hgSu42w+2xYl3+rzIhQqxXhaP232t/b3ilJO00ZZ19d4KICGcakeiL6ZBtD8TrtkRiewI3v0 o8rUBWtjcDRgg3tWx/PcJvZnw1twbmRdaNvsvnlapD2Y9Js3woRLIjSAGOijwzFXSJyC2HU1 AAuR9uo4/QkeIrQVHIxP7TJZdJ9sGEWdeGPzzPlKLHwIX2HzfbdtPejPSXm5LJ026qdtJHgz BAb3NygZG6BH6EC1NPDQ6O53EXorXS1tsSAgp5ZDSFEBklpRVT3E0NrDABEBAAGJAh8EGAEC AAkFAk6Jf0UCGwwACgkQI9DQutE9ekMLBQ//U+Mt9DtFpzMCIHFPE9nNlsCm75j22lNiw6mX mx3cUA3pl+uRGQr/zQC5inQNtjFUmwGkHqrAw+SmG5gsgnM4pSdYvraWaCWOZCQCx1lpaCOl MotrNcwMJTJLQGc4BjJyOeSH59HQDitKfKMu/yjRhzT8CXhys6R0kYMrEN0tbe1cFOJkxSbV 0GgRTDF4PKyLT+RncoKxQe8lGxuk5614aRpBQa0LPafkirwqkUtxsPnarkPUEfkBlnIhAR8L kmneYLu0AvbWjfJCUH7qfpyS/FRrQCoBq9QIEcf2v1f0AIpA27f9KCEv5MZSHXGCdNcbjKw1 39YxYZhmXaHFKDSZIC29YhQJeXWlfDEDq6nIhvurZy3mSh2OMQgaIoFexPCsBBOclH8QUtMk a3jW/qYyrV+qUq9Wf3SKPrXf7B3xB332jFCETbyZQXqmowV+2b3rJFRWn5hK5B+xwvuxKyGq qDOGjof2dKl2zBIxbFgOclV7wqCVkhxSJi/QaOj2zBqSNPXga5DWtX3ekRnJLa1+ijXxmdjz hApihi08gwvP5G9fNGKQyRETePEtEAWt0b7dOqMzYBYGRVr7uS4uT6WP7fzOwAJC4lU7ZYWZ yVshCa0IvTtp1085RtT3qhh9mobkcZ+7cQOY+Tx2RGXS9WeOh2jZjdoWUv6CevXNQyOUXMM= Organization: ARM Ltd Message-ID: <4e475e1f-80f2-372a-2c16-a03ac947525a@arm.com> Date: Wed, 24 Apr 2019 15:29:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190424133903.GU3567@e103592.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/04/2019 14:39, Dave Martin wrote: > On Tue, Apr 23, 2019 at 10:12:35AM +0530, Amit Daniel Kachhap wrote: >> From: Mark Rutland >> >> When pointer authentication is supported, a guest may wish to use it. >> This patch adds the necessary KVM infrastructure for this to work, with >> a semi-lazy context switch of the pointer auth state. >> >> Pointer authentication feature is only enabled when VHE is built >> in the kernel and present in the CPU implementation so only VHE code >> paths are modified. >> >> When we schedule a vcpu, we disable guest usage of pointer >> authentication instructions and accesses to the keys. While these are >> disabled, we avoid context-switching the keys. When we trap the guest >> trying to use pointer authentication functionality, we change to eagerly >> context-switching the keys, and enable the feature. The next time the >> vcpu is scheduled out/in, we start again. However the host key save is >> optimized and implemented inside ptrauth instruction/register access >> trap. >> >> Pointer authentication consists of address authentication and generic >> authentication, and CPUs in a system might have varied support for >> either. Where support for either feature is not uniform, it is hidden >> from guests via ID register emulation, as a result of the cpufeature >> framework in the host. >> >> Unfortunately, address authentication and generic authentication cannot >> be trapped separately, as the architecture provides a single EL2 trap >> covering both. If we wish to expose one without the other, we cannot >> prevent a (badly-written) guest from intermittently using a feature >> which is not uniformly supported (when scheduled on a physical CPU which >> supports the relevant feature). Hence, this patch expects both type of >> authentication to be present in a cpu. >> >> This switch of key is done from guest enter/exit assembly as preparation >> for the upcoming in-kernel pointer authentication support. Hence, these >> key switching routines are not implemented in C code as they may cause >> pointer authentication key signing error in some situations. >> >> Signed-off-by: Mark Rutland >> [Only VHE, key switch in full assembly, vcpu_has_ptrauth checks >> , save host key in ptrauth exception trap] >> Signed-off-by: Amit Daniel Kachhap >> Reviewed-by: Julien Thierry >> Cc: Marc Zyngier >> Cc: Christoffer Dall >> Cc: kvmarm@lists.cs.columbia.edu >> --- >> Changes since v9: >> >> * Removed hardcoding of enum values[Mark Zyngier]. >> * Changed kvm_ptrauth_asm.h to kvm_ptrauth.h[Mark Zyngier]. >> * Removed macro __ptrauth_save_state and applied inline [Marc Zyngier]. >> * Moved kvm_arm_vcpu_ptrauth_setup_lazy, kvm_arm_vcpu_ptrauth_enable and >> kvm_arm_vcpu_ptrauth_disable from *.c to kvm_emulate.h file [Marc Zyngier]. >> * Added/Modified comments at few places [Marc Zyngier]. > > [...] > >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > [...] > >> @@ -1058,9 +1087,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, >> (0xfUL << ID_AA64ISAR1_API_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPI_SHIFT); >> - if (val & ptrauth_mask) >> - kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> - val &= ~ptrauth_mask; >> + if (!vcpu_has_ptrauth(vcpu)) { >> + if (val & ptrauth_mask) >> + kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> + val &= ~ptrauth_mask; >> + } > > Hmmm, didn't spot this before, but this error message no longer makes > sense now that KVM _does_ support pointer auth. > > Without vcpu_has_ptrauth(vcpu), we should just silently mask out the > relevant ID fields now (same as for SVE). > > The patch below should achieve that. > > --8<-- > > From c6065122c5cccef57108dff990ce8fb43426f88e Mon Sep 17 00:00:00 2001 > From: Dave Martin > Date: Wed, 24 Apr 2019 14:32:29 +0100 > Subject: [PATCH] KVM: arm64: sys_regs: Remove warning about missing pointer > auth support > > KVM does support pointer auth for guests now, so it is > inappropriate (and confusing) to print a warning to dmesg when > userspace explicitly does not ask for pointer auth to be turned on > for a vcpu. > > So, just squash the virtual ptrauth ID_AA64ISAR1_EL1 fields when > appropriate and remove the warning. > > Signed-off-by: Dave Martin > --- > arch/arm64/kvm/sys_regs.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 7f06c2e..f599f5e 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1082,16 +1082,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, > > if (id == SYS_ID_AA64PFR0_EL1 && !vcpu_has_sve(vcpu)) { > val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); > - } else if (id == SYS_ID_AA64ISAR1_EL1) { > - const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_API_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPI_SHIFT); > - if (!vcpu_has_ptrauth(vcpu)) { > - if (val & ptrauth_mask) > - kvm_debug("ptrauth unsupported for guests, suppressing\n"); > - val &= ~ptrauth_mask; > - } > + } else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { > + val &= ~((0xfUL << ID_AA64ISAR1_APA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_API_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPI_SHIFT)); > } > > return val; > Since the series isn't in -next yet, I've squashed the above with the other nits I had in -queue. Thanks, M. -- Jazz is not dead. It just smells funny... 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Wed, 24 Apr 2019 07:29:29 -0700 (PDT) Received: from [10.1.196.92] (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B526D3F5AF; Wed, 24 Apr 2019 07:29:27 -0700 (PDT) Subject: Re: [PATCH v10 2/5] KVM: arm/arm64: context-switch ptrauth registers To: Dave Martin , Amit Daniel Kachhap References: <1555994558-26349-1-git-send-email-amit.kachhap@arm.com> <1555994558-26349-3-git-send-email-amit.kachhap@arm.com> <20190424133903.GU3567@e103592.cambridge.arm.com> From: Marc Zyngier Openpgp: preference=signencrypt Autocrypt: addr=marc.zyngier@arm.com; prefer-encrypt=mutual; keydata= mQINBE6Jf0UBEADLCxpix34Ch3kQKA9SNlVQroj9aHAEzzl0+V8jrvT9a9GkK+FjBOIQz4KE g+3p+lqgJH4NfwPm9H5I5e3wa+Scz9wAqWLTT772Rqb6hf6kx0kKd0P2jGv79qXSmwru28vJ t9NNsmIhEYwS5eTfCbsZZDCnR31J6qxozsDHpCGLHlYym/VbC199Uq/pN5gH+5JHZyhyZiNW ozUCjMqC4eNW42nYVKZQfbj/k4W9xFfudFaFEhAf/Vb1r6F05eBP1uopuzNkAN7vqS8XcgQH qXI357YC4ToCbmqLue4HK9+2mtf7MTdHZYGZ939OfTlOGuxFW+bhtPQzsHiW7eNe0ew0+LaL 3wdNzT5abPBscqXWVGsZWCAzBmrZato+Pd2bSCDPLInZV0j+rjt7MWiSxEAEowue3IcZA++7 ifTDIscQdpeKT8hcL+9eHLgoSDH62SlubO/y8bB1hV8JjLW/jQpLnae0oz25h39ij4ijcp8N t5slf5DNRi1NLz5+iaaLg4gaM3ywVK2VEKdBTg+JTg3dfrb3DH7ctTQquyKun9IVY8AsxMc6 lxl4HxrpLX7HgF10685GG5fFla7R1RUnW5svgQhz6YVU33yJjk5lIIrrxKI/wLlhn066mtu1 DoD9TEAjwOmpa6ofV6rHeBPehUwMZEsLqlKfLsl0PpsJwov8TQARAQABtCNNYXJjIFp5bmdp ZXIgPG1hcmMuenluZ2llckBhcm0uY29tPokCOwQTAQIAJQIbAwYLCQgHAwIGFQgCCQoLBBYC AwECHgECF4AFAk6NvYYCGQEACgkQI9DQutE9ekObww/+NcUATWXOcnoPflpYG43GZ0XjQLng LQFjBZL+CJV5+1XMDfz4ATH37cR+8gMO1UwmWPv5tOMKLHhw6uLxGG4upPAm0qxjRA/SE3LC 22kBjWiSMrkQgv5FDcwdhAcj8A+gKgcXBeyXsGBXLjo5UQOGvPTQXcqNXB9A3ZZN9vS6QUYN TXFjnUnzCJd+PVI/4jORz9EUVw1q/+kZgmA8/GhfPH3xNetTGLyJCJcQ86acom2liLZZX4+1 6Hda2x3hxpoQo7pTu+XA2YC4XyUstNDYIsE4F4NVHGi88a3N8yWE+Z7cBI2HjGvpfNxZnmKX 6bws6RQ4LHDPhy0yzWFowJXGTqM/e79c1UeqOVxKGFF3VhJJu1nMlh+5hnW4glXOoy/WmDEM UMbl9KbJUfo+GgIQGMp8mwgW0vK4HrSmevlDeMcrLdfbbFbcZLNeFFBn6KqxFZaTd+LpylIH bOPN6fy1Dxf7UZscogYw5Pt0JscgpciuO3DAZo3eXz6ffj2NrWchnbj+SpPBiH4srfFmHY+Y LBemIIOmSqIsjoSRjNEZeEObkshDVG5NncJzbAQY+V3Q3yo9og/8ZiaulVWDbcpKyUpzt7pv cdnY3baDE8ate/cymFP5jGJK++QCeA6u6JzBp7HnKbngqWa6g8qDSjPXBPCLmmRWbc5j0lvA 6ilrF8m5Ag0ETol/RQEQAM/2pdLYCWmf3rtIiP8Wj5NwyjSL6/UrChXtoX9wlY8a4h3EX6E3 64snIJVMLbyr4bwdmPKULlny7T/R8dx/mCOWu/DztrVNQiXWOTKJnd/2iQblBT+W5W8ep/nS w3qUIckKwKdplQtzSKeE+PJ+GMS+DoNDDkcrVjUnsoCEr0aK3cO6g5hLGu8IBbC1CJYSpple VVb/sADnWF3SfUvJ/l4K8Uk4B4+X90KpA7U9MhvDTCy5mJGaTsFqDLpnqp/yqaT2P7kyMG2E w+eqtVIqwwweZA0S+tuqput5xdNAcsj2PugVx9tlw/LJo39nh8NrMxAhv5aQ+JJ2I8UTiHLX QvoC0Yc/jZX/JRB5r4x4IhK34Mv5TiH/gFfZbwxd287Y1jOaD9lhnke1SX5MXF7eCT3cgyB+ hgSu42w+2xYl3+rzIhQqxXhaP232t/b3ilJO00ZZ19d4KICGcakeiL6ZBtD8TrtkRiewI3v0 o8rUBWtjcDRgg3tWx/PcJvZnw1twbmRdaNvsvnlapD2Y9Js3woRLIjSAGOijwzFXSJyC2HU1 AAuR9uo4/QkeIrQVHIxP7TJZdJ9sGEWdeGPzzPlKLHwIX2HzfbdtPejPSXm5LJ026qdtJHgz BAb3NygZG6BH6EC1NPDQ6O53EXorXS1tsSAgp5ZDSFEBklpRVT3E0NrDABEBAAGJAh8EGAEC AAkFAk6Jf0UCGwwACgkQI9DQutE9ekMLBQ//U+Mt9DtFpzMCIHFPE9nNlsCm75j22lNiw6mX mx3cUA3pl+uRGQr/zQC5inQNtjFUmwGkHqrAw+SmG5gsgnM4pSdYvraWaCWOZCQCx1lpaCOl MotrNcwMJTJLQGc4BjJyOeSH59HQDitKfKMu/yjRhzT8CXhys6R0kYMrEN0tbe1cFOJkxSbV 0GgRTDF4PKyLT+RncoKxQe8lGxuk5614aRpBQa0LPafkirwqkUtxsPnarkPUEfkBlnIhAR8L kmneYLu0AvbWjfJCUH7qfpyS/FRrQCoBq9QIEcf2v1f0AIpA27f9KCEv5MZSHXGCdNcbjKw1 39YxYZhmXaHFKDSZIC29YhQJeXWlfDEDq6nIhvurZy3mSh2OMQgaIoFexPCsBBOclH8QUtMk a3jW/qYyrV+qUq9Wf3SKPrXf7B3xB332jFCETbyZQXqmowV+2b3rJFRWn5hK5B+xwvuxKyGq qDOGjof2dKl2zBIxbFgOclV7wqCVkhxSJi/QaOj2zBqSNPXga5DWtX3ekRnJLa1+ijXxmdjz hApihi08gwvP5G9fNGKQyRETePEtEAWt0b7dOqMzYBYGRVr7uS4uT6WP7fzOwAJC4lU7ZYWZ yVshCa0IvTtp1085RtT3qhh9mobkcZ+7cQOY+Tx2RGXS9WeOh2jZjdoWUv6CevXNQyOUXMM= Organization: ARM Ltd Message-ID: <4e475e1f-80f2-372a-2c16-a03ac947525a@arm.com> Date: Wed, 24 Apr 2019 15:29:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190424133903.GU3567@e103592.cambridge.arm.com> Content-Language: en-US Cc: Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Kristina Martsenko , Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Message-ID: <20190424142926.ziZka4uW6r0EyNC7tAJCWCGspGwCX3yF3nXXtlfK9mk@z> On 24/04/2019 14:39, Dave Martin wrote: > On Tue, Apr 23, 2019 at 10:12:35AM +0530, Amit Daniel Kachhap wrote: >> From: Mark Rutland >> >> When pointer authentication is supported, a guest may wish to use it. >> This patch adds the necessary KVM infrastructure for this to work, with >> a semi-lazy context switch of the pointer auth state. >> >> Pointer authentication feature is only enabled when VHE is built >> in the kernel and present in the CPU implementation so only VHE code >> paths are modified. >> >> When we schedule a vcpu, we disable guest usage of pointer >> authentication instructions and accesses to the keys. While these are >> disabled, we avoid context-switching the keys. When we trap the guest >> trying to use pointer authentication functionality, we change to eagerly >> context-switching the keys, and enable the feature. The next time the >> vcpu is scheduled out/in, we start again. However the host key save is >> optimized and implemented inside ptrauth instruction/register access >> trap. >> >> Pointer authentication consists of address authentication and generic >> authentication, and CPUs in a system might have varied support for >> either. Where support for either feature is not uniform, it is hidden >> from guests via ID register emulation, as a result of the cpufeature >> framework in the host. >> >> Unfortunately, address authentication and generic authentication cannot >> be trapped separately, as the architecture provides a single EL2 trap >> covering both. If we wish to expose one without the other, we cannot >> prevent a (badly-written) guest from intermittently using a feature >> which is not uniformly supported (when scheduled on a physical CPU which >> supports the relevant feature). Hence, this patch expects both type of >> authentication to be present in a cpu. >> >> This switch of key is done from guest enter/exit assembly as preparation >> for the upcoming in-kernel pointer authentication support. Hence, these >> key switching routines are not implemented in C code as they may cause >> pointer authentication key signing error in some situations. >> >> Signed-off-by: Mark Rutland >> [Only VHE, key switch in full assembly, vcpu_has_ptrauth checks >> , save host key in ptrauth exception trap] >> Signed-off-by: Amit Daniel Kachhap >> Reviewed-by: Julien Thierry >> Cc: Marc Zyngier >> Cc: Christoffer Dall >> Cc: kvmarm@lists.cs.columbia.edu >> --- >> Changes since v9: >> >> * Removed hardcoding of enum values[Mark Zyngier]. >> * Changed kvm_ptrauth_asm.h to kvm_ptrauth.h[Mark Zyngier]. >> * Removed macro __ptrauth_save_state and applied inline [Marc Zyngier]. >> * Moved kvm_arm_vcpu_ptrauth_setup_lazy, kvm_arm_vcpu_ptrauth_enable and >> kvm_arm_vcpu_ptrauth_disable from *.c to kvm_emulate.h file [Marc Zyngier]. >> * Added/Modified comments at few places [Marc Zyngier]. > > [...] > >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > [...] > >> @@ -1058,9 +1087,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, >> (0xfUL << ID_AA64ISAR1_API_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPI_SHIFT); >> - if (val & ptrauth_mask) >> - kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> - val &= ~ptrauth_mask; >> + if (!vcpu_has_ptrauth(vcpu)) { >> + if (val & ptrauth_mask) >> + kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> + val &= ~ptrauth_mask; >> + } > > Hmmm, didn't spot this before, but this error message no longer makes > sense now that KVM _does_ support pointer auth. > > Without vcpu_has_ptrauth(vcpu), we should just silently mask out the > relevant ID fields now (same as for SVE). > > The patch below should achieve that. > > --8<-- > > From c6065122c5cccef57108dff990ce8fb43426f88e Mon Sep 17 00:00:00 2001 > From: Dave Martin > Date: Wed, 24 Apr 2019 14:32:29 +0100 > Subject: [PATCH] KVM: arm64: sys_regs: Remove warning about missing pointer > auth support > > KVM does support pointer auth for guests now, so it is > inappropriate (and confusing) to print a warning to dmesg when > userspace explicitly does not ask for pointer auth to be turned on > for a vcpu. > > So, just squash the virtual ptrauth ID_AA64ISAR1_EL1 fields when > appropriate and remove the warning. > > Signed-off-by: Dave Martin > --- > arch/arm64/kvm/sys_regs.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 7f06c2e..f599f5e 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1082,16 +1082,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, > > if (id == SYS_ID_AA64PFR0_EL1 && !vcpu_has_sve(vcpu)) { > val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); > - } else if (id == SYS_ID_AA64ISAR1_EL1) { > - const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_API_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPI_SHIFT); > - if (!vcpu_has_ptrauth(vcpu)) { > - if (val & ptrauth_mask) > - kvm_debug("ptrauth unsupported for guests, suppressing\n"); > - val &= ~ptrauth_mask; > - } > + } else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { > + val &= ~((0xfUL << ID_AA64ISAR1_APA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_API_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPI_SHIFT)); > } > > return val; > Since the series isn't in -next yet, I've squashed the above with the other nits I had in -queue. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 4ADB8C10F11 for ; Wed, 24 Apr 2019 14:29:42 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1B16120811 for ; 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Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190424133903.GU3567@e103592.cambridge.arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190424_072930_211433_1D1B6987 X-CRM114-Status: GOOD ( 33.47 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Kristina Martsenko , Ramana Radhakrishnan , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 24/04/2019 14:39, Dave Martin wrote: > On Tue, Apr 23, 2019 at 10:12:35AM +0530, Amit Daniel Kachhap wrote: >> From: Mark Rutland >> >> When pointer authentication is supported, a guest may wish to use it. >> This patch adds the necessary KVM infrastructure for this to work, with >> a semi-lazy context switch of the pointer auth state. >> >> Pointer authentication feature is only enabled when VHE is built >> in the kernel and present in the CPU implementation so only VHE code >> paths are modified. >> >> When we schedule a vcpu, we disable guest usage of pointer >> authentication instructions and accesses to the keys. While these are >> disabled, we avoid context-switching the keys. When we trap the guest >> trying to use pointer authentication functionality, we change to eagerly >> context-switching the keys, and enable the feature. The next time the >> vcpu is scheduled out/in, we start again. However the host key save is >> optimized and implemented inside ptrauth instruction/register access >> trap. >> >> Pointer authentication consists of address authentication and generic >> authentication, and CPUs in a system might have varied support for >> either. Where support for either feature is not uniform, it is hidden >> from guests via ID register emulation, as a result of the cpufeature >> framework in the host. >> >> Unfortunately, address authentication and generic authentication cannot >> be trapped separately, as the architecture provides a single EL2 trap >> covering both. If we wish to expose one without the other, we cannot >> prevent a (badly-written) guest from intermittently using a feature >> which is not uniformly supported (when scheduled on a physical CPU which >> supports the relevant feature). Hence, this patch expects both type of >> authentication to be present in a cpu. >> >> This switch of key is done from guest enter/exit assembly as preparation >> for the upcoming in-kernel pointer authentication support. Hence, these >> key switching routines are not implemented in C code as they may cause >> pointer authentication key signing error in some situations. >> >> Signed-off-by: Mark Rutland >> [Only VHE, key switch in full assembly, vcpu_has_ptrauth checks >> , save host key in ptrauth exception trap] >> Signed-off-by: Amit Daniel Kachhap >> Reviewed-by: Julien Thierry >> Cc: Marc Zyngier >> Cc: Christoffer Dall >> Cc: kvmarm@lists.cs.columbia.edu >> --- >> Changes since v9: >> >> * Removed hardcoding of enum values[Mark Zyngier]. >> * Changed kvm_ptrauth_asm.h to kvm_ptrauth.h[Mark Zyngier]. >> * Removed macro __ptrauth_save_state and applied inline [Marc Zyngier]. >> * Moved kvm_arm_vcpu_ptrauth_setup_lazy, kvm_arm_vcpu_ptrauth_enable and >> kvm_arm_vcpu_ptrauth_disable from *.c to kvm_emulate.h file [Marc Zyngier]. >> * Added/Modified comments at few places [Marc Zyngier]. > > [...] > >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > [...] > >> @@ -1058,9 +1087,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, >> (0xfUL << ID_AA64ISAR1_API_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | >> (0xfUL << ID_AA64ISAR1_GPI_SHIFT); >> - if (val & ptrauth_mask) >> - kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> - val &= ~ptrauth_mask; >> + if (!vcpu_has_ptrauth(vcpu)) { >> + if (val & ptrauth_mask) >> + kvm_debug("ptrauth unsupported for guests, suppressing\n"); >> + val &= ~ptrauth_mask; >> + } > > Hmmm, didn't spot this before, but this error message no longer makes > sense now that KVM _does_ support pointer auth. > > Without vcpu_has_ptrauth(vcpu), we should just silently mask out the > relevant ID fields now (same as for SVE). > > The patch below should achieve that. > > --8<-- > > From c6065122c5cccef57108dff990ce8fb43426f88e Mon Sep 17 00:00:00 2001 > From: Dave Martin > Date: Wed, 24 Apr 2019 14:32:29 +0100 > Subject: [PATCH] KVM: arm64: sys_regs: Remove warning about missing pointer > auth support > > KVM does support pointer auth for guests now, so it is > inappropriate (and confusing) to print a warning to dmesg when > userspace explicitly does not ask for pointer auth to be turned on > for a vcpu. > > So, just squash the virtual ptrauth ID_AA64ISAR1_EL1 fields when > appropriate and remove the warning. > > Signed-off-by: Dave Martin > --- > arch/arm64/kvm/sys_regs.c | 15 +++++---------- > 1 file changed, 5 insertions(+), 10 deletions(-) > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > index 7f06c2e..f599f5e 100644 > --- a/arch/arm64/kvm/sys_regs.c > +++ b/arch/arm64/kvm/sys_regs.c > @@ -1082,16 +1082,11 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, > > if (id == SYS_ID_AA64PFR0_EL1 && !vcpu_has_sve(vcpu)) { > val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); > - } else if (id == SYS_ID_AA64ISAR1_EL1) { > - const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_API_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > - (0xfUL << ID_AA64ISAR1_GPI_SHIFT); > - if (!vcpu_has_ptrauth(vcpu)) { > - if (val & ptrauth_mask) > - kvm_debug("ptrauth unsupported for guests, suppressing\n"); > - val &= ~ptrauth_mask; > - } > + } else if (id == SYS_ID_AA64ISAR1_EL1 && !vcpu_has_ptrauth(vcpu)) { > + val &= ~((0xfUL << ID_AA64ISAR1_APA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_API_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPA_SHIFT) | > + (0xfUL << ID_AA64ISAR1_GPI_SHIFT)); > } > > return val; > Since the series isn't in -next yet, I've squashed the above with the other nits I had in -queue. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel