From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752896AbeDLOdP (ORCPT ); Thu, 12 Apr 2018 10:33:15 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40152 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752303AbeDLOdN (ORCPT ); Thu, 12 Apr 2018 10:33:13 -0400 Subject: Re: [PATCH 04/10] KVM: Introduce a new guest mapping API To: KarimAllah Ahmed , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: hpa@zytor.com, jmattson@google.com, mingo@redhat.com, rkrcmar@redhat.com, tglx@linutronix.de References: <1519235241-6500-1-git-send-email-karahmed@amazon.de> <1519235241-6500-5-git-send-email-karahmed@amazon.de> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0f UGFvbG8gQm9uemluaSA8Ym9uemluaUBnbnUub3JnPsLBTQQTAQIAIwUCVEJ7AwIbAwcLCQgH AwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEH4VEAzNNmmxNcwOniaZVLsuy1lW/ntYCA0Caz0i sHpmecK8aWlvL9wpQCk4GlOX9L1emyYXZPmzIYB0IRqmSzAlZxi+A2qm9XOxs5gJ2xqMEXX5 FMtUH3kpkWWJeLqe7z0EoQdUI4EG988uv/tdZyqjUn2XJE+K01x7r3MkUSFz/HZKZiCvYuze VlS0NTYdUt5jBXualvAwNKfxEkrxeHjxgdFHjYWhjflahY7TNRmuqPM/Lx7wAuyoDjlYNE40 Z+Kun4/KjMbjgpcF4Nf3PJQR8qXI6p3so2qsSn91tY7DFSJO6v2HwFJkC2jU95wxfNmTEUZc znXahYbVOwCDJRuPrE5GKFd/XJU9u5hNtr/uYipHij01WXal2cce1S5mn1/HuM1yo1u8xdHy IupCd57EWI948e8BlhpujUCU2tzOb2iYS0kpmJ9/oLVZrOcSZCcCl2P0AaCAsj59z2kwQS9D du0WxUs8waso0Qq6tDEHo8yLCOJDzSz4oojTtWe4zsulVnWV+wu70AioemAT8S6JOtlu60C5 dHgQUD1Tp+ReXpDKXmjbASJx4otvW0qah3o6JaqO79tbDqIvncu3tewwp6c85uZd48JnIOh3 utBAu684nJakbbvZUGikJfxd887ATQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAem Vv9Yfn2PbDIbxXqLff7oyVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CR wkMHtOmzQiQ2tSLjKh/cHeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuf fAb589AJW50kkQK9VD/9QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v02 8TVAaYbIhxvDY0hUQE4r8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQ zCYHXAzwnGi8WU9iuE1P0wARAQABwsEzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EO oJy0uZggJm7gZKeJ7iUpeX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBT uiJ0bfo55SWsUNN+c9hhIX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHn plOzCXHvmdlW0i6SrMsBDl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4 HYv/7ZnASVkR5EERFF3+6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz 876SvcOb5SL5SKg9/rCBufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvr iy9enJ8kxJwhC0ECbSKFY+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y 1lJAPPSIqZKvHzGShdh8DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT /ujKaGd4vxG2Ei+MMNDmS1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO 53DliFMkVTecLptsXaesuUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: Date: Thu, 12 Apr 2018 16:33:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1519235241-6500-5-git-send-email-karahmed@amazon.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Coming back to this (nice) series. On 21/02/2018 18:47, KarimAllah Ahmed wrote: > +bool kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map) > +{ > + kvm_pfn_t pfn; > + void *kaddr = NULL; Can we s/kaddr/hva/ since that's the standard nomenclature? > + struct page *page = NULL; > + > + if (map->kaddr && map->gfn == gfn) > + /* If the mapping is valid and guest memory is already mapped */ > + return true; Please return 0/-EINVAL instead. More important, this optimization is problematic because: 1) the underlying memslots array could have changed. You'd also need to store the generation count (see kvm_read_guest_cached for an example) 2) worse, the memslots array could have switched between the SMM and non-SMM address spaces. This is by the way the reason why there is no kvm_vcpu_read_guest_cached API. However, all the places you're changing in patches 4-10 are doing already kvm_vcpu_gpa_to_page, so I suggest just dropping this optimization. > + else if (map->kaddr) > + /* If the mapping is valid but trying to map a different guest pfn */ > + kvm_vcpu_unmap(map); > + > + pfn = kvm_vcpu_gfn_to_pfn(vcpu, gfn); Please change the API to: static int __kvm_map_gfn(struct kvm_memslot *memslots, gfn_t gfn, struct kvm_host_map *map) calling gfn_to_pfn_memslot(memslots, gfn) int kvm_vcpu_map_gfn(struct kvm_vcpu *vcpu gfn_t gfn, struct kvm_host_map *map) calling kvm_vcpu_gfn_to_memslot + __kvm_map void kvm_unmap_gfn(struct kvm_host_map *map) > + if (is_error_pfn(pfn)) > + return false; Should this be is_error_noslot_pfn? > + if (pfn_valid(pfn)) { > + page = pfn_to_page(pfn); > + kaddr = vmap(&page, 1, VM_MAP, PAGE_KERNEL); > + } else { > + kaddr = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB); > + } > + > + if (!kaddr) > + return false; > + > + map->page = page; > + map->kaddr = kaddr; > + map->pfn = pfn; > + map->gfn = gfn; > + > + return true; > +} > > +void kvm_vcpu_unmap(struct kvm_host_map *map) > +{ > + if (!map->kaddr) > + return; > + > + if (map->page) > + kunmap(map->page); > + else > + memunmap(map->kaddr); > + > + kvm_release_pfn_dirty(map->pfn); > + memset(map, 0, sizeof(*map)); This can clear just map->kaddr (map->hva after the above review). Thanks, Paolo > +} > +