From patchwork Tue May 3 18:30:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Gardon X-Patchwork-Id: 12836070 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 15732C433EF for ; Tue, 3 May 2022 18:30:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235501AbiECSe1 (ORCPT ); Tue, 3 May 2022 14:34:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51244 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241376AbiECSeX (ORCPT ); Tue, 3 May 2022 14:34:23 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B1EA3F315 for ; Tue, 3 May 2022 11:30:49 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id j8-20020aa78d08000000b0050ade744b37so9797120pfe.16 for ; Tue, 03 May 2022 11:30:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=D/b4lmpRV1S4oq77zyZLQ2hr9b7x70TzpN91Y4dw1/o=; b=Y+EEi8961TGB6nwmrqnfcn6/9luwRSHrafK/WssjZWrEiHFgeIK4J3IpKOjYCgzVTI 4PcP2XL0neruyqzq8G4FIUx7JY2fh4EbQzHUEUmFT/6ITTJxwm/yYdlzeTaDYMDdGbyI RbGdAlbGZD1DZh2ZnoWXR4T9QEDnbQQWV8ZDknY6La9xAmmCWX/b8dFqimLe/MbKRlVF wr+8AEVLV0613KS5XzCfmCjcnHOSXXpnYGoSARVC1FPLW07ijevaJxSO+QBHwj8b7ruU QtQDOiN+ZTPjO8R/177zYpZMDjvuj6MWXujsGg3050rpaV3OyeRbr3vDNUZrHNB/hG0t 2x6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=D/b4lmpRV1S4oq77zyZLQ2hr9b7x70TzpN91Y4dw1/o=; b=SY+rcT5XJGzv7H1yCuSfKPhRV6QYJLCB/V05c/yPXsFy3ZYj1M1NOOPHPVPOIzt/lL ZunktsZ/5+9eV+2oOSj5cQMzU90Ge8s0ZsCqgjNFOGo8UqScFjbhncP2ZcTvXDQK06F/ jwfbwxU5Q9dl8QWooQIdd+C3lY/VsywbAXwsk2Xbira5REeYJtSPEZWEvRWp5/1AbtOk yDrscu8PRTmZLAb//G5teZ+vAtK4m+bn/HfvBzLpb4uoma8KV6V+eg75mKBATflKgTJO l+PEKeTlxYaoJiNG8AOOSNHEqbdkCy0WbUAtise4RVJy7OLf5Vbhdj4KTP6qvuuNwFA4 A1Ug== X-Gm-Message-State: AOAM530dTvyAZ64tGfzp8uCHUNsUbZ2ljvebwTc4GUJMLj1z3n8Fvd81 ZISp9YjjjpZHzbhNn1jqDTEsTvKGgGTS X-Google-Smtp-Source: ABdhPJwK9diAS9QQDrYi4VIkhuWWuos+YheFi4FTQhhWZtc53Uo8yOtdb91nwtZcJk6M5+5PsI76ObJ1jUGU X-Received: from sweer.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:e45]) (user=bgardon job=sendgmr) by 2002:a17:902:a613:b0:156:b53d:c137 with SMTP id u19-20020a170902a61300b00156b53dc137mr17778009plq.73.1651602648787; Tue, 03 May 2022 11:30:48 -0700 (PDT) Date: Tue, 3 May 2022 18:30:34 +0000 Message-Id: <20220503183045.978509-1-bgardon@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [PATCH v7 00/11] KVM: x86: Add a cap to disable NX hugepages on a VM From: Ben Gardon To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Peter Xu , Sean Christopherson , David Matlack , Jim Mattson , David Dunn , Jing Zhang , Junaid Shahid , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Given the high cost of NX hugepages in terms of TLB performance, it may be desirable to disable the mitigation on a per-VM basis. In the case of public cloud providers with many VMs on a single host, some VMs may be more trusted than others. In order to maximize performance on critical VMs, while still providing some protection to the host from iTLB Multihit, allow the mitigation to be selectively disabled. Disabling NX hugepages on a VM is relatively straightforward, but I took this as an opportunity to add some NX hugepages test coverage and clean up selftests infrastructure a bit. This series was tested with the new selftest and the rest of the KVM selftests on an Intel Haswell machine. Changelog: v1->v2: Dropped the complicated memslot refactor in favor of Ricardo Koller's patch with a similar effect. Incorporated David Dunn's feedback and reviewed by tag: shortened waits to speed up test. v2->v3: Incorporated a suggestion from David on how to build the NX huge pages test. Fixed a build breakage identified by David. Dropped the per-vm nx_huge_pages field in favor of simply checking the global + per-VM disable override. Documented the new capability Separated out the commit to test disabling NX huge pages Removed permission check when checking if the disable NX capability is supported. Added test coverage for the permission check. v3->v4: Collected RB's from Jing and David Modified stat collection to reduce a memory allocation [David] Incorporated various improvments to the NX test [David] Changed the NX disable test to run by default [David] Removed some now unnecessary commits Dropped the code to dump KVM stats from the binary stats test, and factor out parts of the existing test to library functions instead. [David, Jing, Sean] Dropped the improvement to a debugging log message as it's no longer relevant to this series. v4->v5: Incorporated cleanup suggestions from David and Sean Added a patch with style fixes for the binary stats test from Sean Added a restriction that NX huge pages can only be disabled before vCPUs are created [Sean] v5->v6: Scooped up David's RBs Added a magic token to skip nx_huge_pages_test when not run via wrapper script [Sean] Made the call to nx_huge_pages_test in the wrapper script more robust [Sean] Incorportated various nits and comment / documentation suggestions from Sean. Improved negative testing of NX disable without reboot permissions. [Sean] v6->v7: Collected Peter Xu's Reviewed-by tags Added stats metadata caching to kvm_util Misc NX test fixups Ben Gardon (10): KVM: selftests: Remove dynamic memory allocation for stats header KVM: selftests: Read binary stats header in lib KVM: selftests: Read binary stats desc in lib KVM: selftests: Read binary stat data in lib KVM: selftests: Add NX huge pages test KVM: x86: Fix errant brace in KVM capability handling KVM: x86/MMU: Allow NX huge pages to be disabled on a per-vm basis KVM: selftests: Factor out calculation of pages needed for a VM KVM: selftests: Test disabling NX hugepages on a VM KVM: selftests: Cache binary stats metadata for duration of test Sean Christopherson (1): KVM: selftests: Clean up coding style in binary stats test Documentation/virt/kvm/api.rst | 17 ++ arch/x86/include/asm/kvm_host.h | 2 + arch/x86/kvm/mmu.h | 8 +- arch/x86/kvm/mmu/spte.c | 7 +- arch/x86/kvm/mmu/spte.h | 3 +- arch/x86/kvm/mmu/tdp_mmu.c | 2 +- arch/x86/kvm/x86.c | 32 ++- include/uapi/linux/kvm.h | 1 + tools/testing/selftests/kvm/Makefile | 10 + .../selftests/kvm/include/kvm_util_base.h | 13 + .../selftests/kvm/kvm_binary_stats_test.c | 142 +++++----- tools/testing/selftests/kvm/lib/kvm_util.c | 262 ++++++++++++++++-- .../selftests/kvm/lib/kvm_util_internal.h | 5 + .../selftests/kvm/x86_64/nx_huge_pages_test.c | 222 +++++++++++++++ .../kvm/x86_64/nx_huge_pages_test.sh | 46 +++ 15 files changed, 678 insertions(+), 94 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c create mode 100755 tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh