From patchwork Thu Mar 30 08:57:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Stevens X-Patchwork-Id: 13193698 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB216C6FD1D for ; Thu, 30 Mar 2023 08:58:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229980AbjC3I6O (ORCPT ); Thu, 30 Mar 2023 04:58:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229540AbjC3I6M (ORCPT ); Thu, 30 Mar 2023 04:58:12 -0400 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0BE3E4C27 for ; Thu, 30 Mar 2023 01:58:11 -0700 (PDT) Received: by mail-pl1-x630.google.com with SMTP id w4so17438673plg.9 for ; Thu, 30 Mar 2023 01:58:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1680166690; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=khZuI90C3yICc2QlVMZxoINj4hbBwgvv4lkvCwQn0oM=; b=EXT9oCu6maH6hdfTnR/yspZUXl4VC9pYBcFM28HOWhVhVGfjKr06H97hxY5NEcXDVy O6AYwjuUW+eoRs3XHt58Vt+g8j0rm222Dq96fo5vNQMf/niag4j/MHyFyVmXmvni74E6 /YSWF5zCloCKf2Ewpv0BTU/CsQe8NgLXcgDAc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680166690; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=khZuI90C3yICc2QlVMZxoINj4hbBwgvv4lkvCwQn0oM=; b=vwy9SJeNQ1QpMSDx6udrHb+BsG3IT5VOjU12+Q8ztuJZ5ZgdBF0OwL44//soLTrbWN P0EGC0E5u800w1h6APjFT6ZE2r7kYV9WLAwkWe/FtgLlnrHO5tKgJyXkKk7n5wQywR8J /uaixJn8geGwcnI9tgt0Wqvhqd4NVh6wormLTXu6Wab8+QvpepW67zMm5UiwiGuUyLmN N8Lo2I3ehzuZNjsl2aYO4ePBdsefwWg0XFke2sgHmalo0eBK0hLWJ6wR6e6dso3rrcfH zRDN4Frz/ybg99auf/aHVfH7XHVGk9X+zqePsQ8sobFaTbLw0rP84adJ0tazo8I6S/t6 zBEA== X-Gm-Message-State: AAQBX9eLx820yt4gJyRnzMON7RCO588C1wbOr4IuXO5BRfDjVvwGgH0V srPLlEFRPEKGuq5ZbeDserOGMQ== X-Google-Smtp-Source: AKy350ZDrTpkuW3KLUjaRcClMpQ+xS+Gsu2ak5nMpigAHapulHNWYWEUZil+IM2Hxt1/98K3/CNwAQ== X-Received: by 2002:a17:903:11ce:b0:1a1:da3c:6065 with SMTP id q14-20020a17090311ce00b001a1da3c6065mr28208585plh.22.1680166690463; Thu, 30 Mar 2023 01:58:10 -0700 (PDT) Received: from localhost ([2401:fa00:8f:203:1320:eef8:d0bb:b161]) by smtp.gmail.com with UTF8SMTPSA id bj4-20020a170902850400b001a076568da9sm7239405plb.216.2023.03.30.01.58.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Mar 2023 01:58:09 -0700 (PDT) From: David Stevens X-Google-Original-From: David Stevens To: Marc Zyngier , Sean Christopherson Cc: Oliver Upton , Paolo Bonzini , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, David Stevens Subject: [PATCH v6 0/4] KVM: allow mapping non-refcounted pages Date: Thu, 30 Mar 2023 17:57:58 +0900 Message-Id: <20230330085802.2414466-1-stevensd@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: David Stevens This patch series adds support for mapping VM_IO and VM_PFNMAP memory that is backed by struct pages that aren't currently being refcounted (e.g. tail pages of non-compound higher order allocations) into the guest. Our use case is virtio-gpu blob resources [1], which directly map host graphics buffers into the guest as "vram" for the virtio-gpu device. This feature currently does not work on systems using the amdgpu driver, as that driver allocates non-compound higher order pages via ttm_pool_alloc_page. Currently, the gfn_to_pfn functions require being able to pin the target pfn, so they fail when the pfn returned by follow_pte isn't a ref-counted page. However, the KVM secondary MMUs do not require that the pfn be pinned, since they are integrated with the mmu notifier API. This series adds a new set of gfn_to_pfn_noref functions which parallel the gfn_to_pfn functions but do not pin the pfn. The new functions return the page from gup if it was present, so callers can use it and call put_page when done. This series updates x86 and arm64 secondary MMUs to the new API. Other MMUs can likely be updated without too much difficulty, but I am not familiar with them and have no way to test them. On the other hand, updating the rest of KVM would require replacing all usages of kvm_vcpu_map with the gfn_to_pfn_cache, which is not at all easy [2]. [1] https://patchwork.kernel.org/project/dri-devel/cover/20200814024000.2485-1-gurchetansingh@chromium.org/ [2] https://lore.kernel.org/all/ZBEEQtmtNPaEqU1i@google.com/ v5 -> v6: - rebase on kvm next branch - rename gfn_to_pfn_page to gfn_to_pfn_noref - fix uninitialized outparam in error case of __kvm_faultin_pfn - add kvm_release_pfn_noref_clean for releasing pfn/page pair v4 -> v5: - rebase on kvm next branch again v3 -> v4: - rebase on kvm next branch again - Add some more context to a comment in ensure_pfn_ref v2 -> v3: - rebase on kvm next branch v1 -> v2: - Introduce new gfn_to_pfn_page functions instead of modifying the behavior of existing gfn_to_pfn functions, to make the change less invasive. - Drop changes to mmu_audit.c - Include Nicholas Piggin's patch to avoid corrupting refcount in the follow_pte case, and use it in depreciated gfn_to_pfn functions. - Rebase on kvm/next David Stevens (4): KVM: mmu: introduce new gfn_to_pfn_noref functions KVM: x86/mmu: use gfn_to_pfn_noref KVM: arm64/mmu: use gfn_to_pfn_noref KVM: mmu: remove over-aggressive warnings arch/arm64/kvm/mmu.c | 21 ++-- arch/x86/kvm/mmu/mmu.c | 29 ++--- arch/x86/kvm/mmu/mmu_internal.h | 1 + arch/x86/kvm/mmu/paging_tmpl.h | 7 +- arch/x86/kvm/x86.c | 5 +- include/linux/kvm_host.h | 18 +++ virt/kvm/kvm_main.c | 214 +++++++++++++++++++++++--------- virt/kvm/kvm_mm.h | 6 +- virt/kvm/pfncache.c | 12 +- 9 files changed, 220 insertions(+), 93 deletions(-)