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Tue, 23 Jul 2019 05:43:39 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D03B03F71F; Tue, 23 Jul 2019 05:43:37 -0700 (PDT) Subject: Re: [PATCH v2 4/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on specific commands To: Auger Eric , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org References: <20190611170336.121706-1-marc.zyngier@arm.com> <20190611170336.121706-5-marc.zyngier@arm.com> <9ff329a3-44f2-1de3-b6cc-58ed38a63665@redhat.com> <1a78d52c-7a31-8981-230b-abe85d11b8ec@arm.com> <8b5e029c-a08f-b86b-7021-5d68ec05d3bd@redhat.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 ZXIgPG1hcmMuenluZ2llckBhcm0uY29tPokCTwQTAQIAOQIbAwYLCQgHAwIGFQgCCQoLBBYC AwECHgECF4AWIQSf1RxT4LVjGP2VnD0j0NC60T16QwUCXR3BUgAKCRAj0NC60T16Qyd/D/9s x0puxd3lI+jdLMEY8sTsNxw/+CZfyKaHtysasZlloLK7ftYhRUc63mMW2mrvgB1GEnXYIdj3 g6Qo4csoDuN+9EBmejh7SglM/h0evOtrY2V5QmZA/e/Pqfj0P3N/Eb5BiB3R4ptLtvKCTsqr 3womxCRqQY3IrMn1s2qfpmeNLUIfCUtgh8opzPtFuFJWVBzbzvhPEApZzMe9Vs1O2P8BQaay QXpbzHaKruthoLICRzS/3UCe0N/mBZQRKHrqhPwvjZdO0KMqjSsPqfukOJ8bl5jZxYk+G/3T 66Z4JUpZ7RkcrX7CvBfZqRo19WyWFfjGz79iVMJNIEkJvJBANbTSiWUC6IkP+zT/zWYzZPXx XRlrKWSBBqJrWQKZBwKOLsL62oQG7ARvpCG9rZ6hd5CLQtPI9dasgTwOIA1OW2mWzi20jDjD cGC9ifJiyWL8L/bgwyL3F/G0R1gxAfnRUknyzqfpLy5cSgwKCYrXOrRqgHoB+12HA/XQUG+k vKW8bbdVk5XZPc5ghdFIlza/pb1946SrIg1AsjaEMZqunh0G7oQhOWHKOd6fH0qg8NssMqQl jLfFiOlgEV2mnaz6XXQe/viXPwa4NCmdXqxeBDpJmrNMtbEbq+QUbgcwwle4Xx2/07ICkyZH +7RvbmZ/dM9cpzMAU53sLxSIVQT5lj23WLkCDQROiX9FARAAz/al0tgJaZ/eu0iI/xaPk3DK NIvr9SsKFe2hf3CVjxriHcRfoTfriycglUwtvKvhvB2Y8pQuWfLtP9Hx3H+YI5a78PO2tU1C JdY5Momd3/aJBuUFP5blbx6n+dLDepQhyQrAp2mVC3NIp4T48n4YxL4Og0MORytWNSeygISv Rordw7qDmEsa7wgFsLUIlhKmmV5VVv+wAOdYXdJ9S8n+XgrxSTgHj5f3QqkDtT0yG8NMLLmY kZpOwWoMumeqn/KppPY/uTIwbYTD56q1UirDDB5kDRL626qm63nF00ByyPY+6BXH22XD8smj f2eHw2szECG/lpD4knYjxROIctdC+gLRhz+Nlf8lEHmvjHgiErfgy/lOIf+AV9lvDF3bztjW M5oP2WGeR7VJfkxcXt4JPdyDIH6GBK7jbD7bFiXf6vMiFCrFeFo/bfa39veKUk7TRlnX13go gIZxqR6IvpkG0PxOu2RGJ7Aje/SjytQFa2NwNGCDe1bH89wm9mfDW3BuZF1o2+y+eVqkPZj0 mzfChEsiNIAY6KPDMVdInILYdTUAC5H26jj9CR4itBUcjE/tMll0n2wYRZ14Y/PM+UosfAhf YfN9t2096M9JebksnTbqp20keDMEBvc3KBkboEfoQLU08NDo7ncReitdLW2xICCnlkNIUQGS WlFVPcTQ2sMAEQEAAYkCHwQYAQIACQUCTol/RQIbDAAKCRAj0NC60T16QwsFD/9T4y30O0Wn MwIgcU8T2c2WwKbvmPbaU2LDqZebHdxQDemX65EZCv/NALmKdA22MVSbAaQeqsDD5KYbmCyC czilJ1i+tpZoJY5kJALHWWloI6Uyi2s1zAwlMktAZzgGMnI55Ifn0dAOK0p8oy7/KNGHNPwJ eHKzpHSRgysQ3S1t7VwU4mTFJtXQaBFMMXg8rItP5GdygrFB7yUbG6TnrXhpGkFBrQs9p+SK vCqRS3Gw+dquQ9QR+QGWciEBHwuSad5gu7QC9taN8kJQfup+nJL8VGtAKgGr1AgRx/a/V/QA ikDbt/0oIS/kxlIdcYJ01xuMrDXf1jFhmGZdocUoNJkgLb1iFAl5daV8MQOrqciG+6tnLeZK HY4xCBoigV7E8KwEE5yUfxBS0yRreNb+pjKtX6pSr1Z/dIo+td/sHfEHffaMUIRNvJlBeqaj BX7ZveskVFafmErkH7HC+7ErIaqoM4aOh/Z0qXbMEjFsWA5yVXvCoJWSHFImL9Bo6PbMGpI0 9eBrkNa1fd6RGcktrX6KNfGZ2POECmKGLTyDC8/kb180YpDJERN48S0QBa3Rvt06ozNgFgZF Wvu5Li5PpY/t/M7AAkLiVTtlhZnJWyEJrQi9O2nXTzlG1PeqGH2ahuRxn7txA5j5PHZEZdL1 Z46HaNmN2hZS/oJ69c1DI5Rcww== Organization: ARM Ltd Message-ID: Date: Tue, 23 Jul 2019 13:43:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <8b5e029c-a08f-b86b-7021-5d68ec05d3bd@redhat.com> Content-Language: en-US Cc: "Raslan, KarimAllah" , "Saidi, Ali" 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="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 23/07/2019 13:25, Auger Eric wrote: > Hi Marc, > > On 7/22/19 12:54 PM, Marc Zyngier wrote: >> Hi Eric, >> >> On 01/07/2019 13:38, Auger Eric wrote: >>> Hi Marc, >>> >>> On 6/11/19 7:03 PM, Marc Zyngier wrote: >>>> The LPI translation cache needs to be discarded when an ITS command >>>> may affect the translation of an LPI (DISCARD and MAPD with V=0) or >>>> the routing of an LPI to a redistributor with disabled LPIs (MOVI, >>>> MOVALL). >>>> >>>> We decide to perform a full invalidation of the cache, irrespective >>>> of the LPI that is affected. Commands are supposed to be rare enough >>>> that it doesn't matter. >>>> >>>> Signed-off-by: Marc Zyngier >>>> --- >>>> virt/kvm/arm/vgic/vgic-its.c | 8 ++++++++ >>>> 1 file changed, 8 insertions(+) >>>> >>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >>>> index 9b6b66204b97..5254bb762e1b 100644 >>>> --- a/virt/kvm/arm/vgic/vgic-its.c >>>> +++ b/virt/kvm/arm/vgic/vgic-its.c >>>> @@ -733,6 +733,8 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its, >>>> * don't bother here since we clear the ITTE anyway and the >>>> * pending state is a property of the ITTE struct. >>>> */ >>>> + vgic_its_invalidate_cache(kvm); >>>> + >>>> its_free_ite(kvm, ite); >>>> return 0; >>>> } >>>> @@ -768,6 +770,8 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its, >>>> ite->collection = collection; >>>> vcpu = kvm_get_vcpu(kvm, collection->target_addr); >>>> >>>> + vgic_its_invalidate_cache(kvm); >>>> + >>>> return update_affinity(ite->irq, vcpu); >>>> } >>>> >>>> @@ -996,6 +1000,8 @@ static void vgic_its_free_device(struct kvm *kvm, struct its_device *device) >>>> list_for_each_entry_safe(ite, temp, &device->itt_head, ite_list) >>>> its_free_ite(kvm, ite); >>>> >>>> + vgic_its_invalidate_cache(kvm); >>>> + >>>> list_del(&device->dev_list); >>>> kfree(device); >>>> } >>>> @@ -1249,6 +1255,8 @@ static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its, >>>> vgic_put_irq(kvm, irq); >>>> } >>>> >>>> + vgic_its_invalidate_cache(kvm); >>> All the commands are executed with the its_lock held. Now we don't take >>> it anymore on the fast cache injection path. Don't we have a window >>> where the move has been applied at table level and the cache is not yet >>> invalidated? Same question for vgic_its_free_device(). >> >> There is definitely a race, but that race is invisible from the guest's >> perspective. The guest can only assume that the command has taken effect >> once a SYNC command has been executed, and it cannot observe that the >> SYNC command has been executed before we have invalidated the cache. >> >> Does this answer your question? > > OK make sense. Thank you for the clarification > > Another question, don't we need to invalidate the cache on MAPC V=0 as > well? Removing the mapping of the collection results in interrupts > belonging to that collection being ignored. If we don't flush the > pending bit will be set? Yup, that's a good point. I think i had that at some point, and ended up dropping it, probably missing the point that the interrupt would be made pending. I'll add this: @@ -1218,6 +1218,7 @@ static int vgic_its_cmd_handle_mapc(struct kvm *kvm, struct vgic_its *its, if (!valid) { vgic_its_free_collection(its, coll_id); + vgic_its_invalidate_cache(kvm); } else { collection = find_collection(its, coll_id); 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