From patchwork Mon Mar 21 23:48:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Gardon X-Patchwork-Id: 12787956 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 67C62C433F5 for ; Mon, 21 Mar 2022 23:49:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233646AbiCUXvT (ORCPT ); Mon, 21 Mar 2022 19:51:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233656AbiCUXvM (ORCPT ); Mon, 21 Mar 2022 19:51:12 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76BA61959FD for ; Mon, 21 Mar 2022 16:49:16 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id ob7-20020a17090b390700b001c692ec6de4so437357pjb.7 for ; Mon, 21 Mar 2022 16:49:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=3m1W1T75EhNPFRfjof7HoQxGZ4zdcLUtCtOcDM/n6y4=; b=bH7mF2kTNI6R9mqs/j3WnNRaTz53LMn3cG+XFNKKsojz7Erkkcrw6O4LzU4qaDoUmk U6emSh7jsHYg0cKvkSk5657wzZvuGxwV9P24j10++KR+L8N4dYhXpUUtHYi2Wn1DDw5k mTet9eA6qZ/EByyry2C8ig+YydTCvmKnPpDQvm4om2lhvE27JMCTarC5Q0d9z+kz2i/K 9RCLcCCXXqsixdkDoSSzyk2xnX15MbqopTzGwi19TW5JyJBgOtNRCztMatkBVPm8mvAP 8uPdYNBbsqDCoyMfQ1CzSP7R0WdHm44rWvN7zRXLjVNY13zAmxgX5JU5r4D0hQS8WNaZ rWBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=3m1W1T75EhNPFRfjof7HoQxGZ4zdcLUtCtOcDM/n6y4=; b=siqafQAr2G/ZBaqmh67i0pMLLSuOmSCUebljb5vUvHba8nkR5CiZMBLlKnlzbOh384 3Ffv05f3y8RRPZgiynVVpLnl4iBEOisx7xr6u54CFq0hHRsYsPaEiL1gIcoGXp8xMG4z sWdAxgZEhgE/ZYcxlT7+D9jRhKLmjQ32TKlrBTKBA8pidfJflLuqOI5sSpzaF52DDgOp OpRyYuyqmeLKdUSrqCDhDOzTSy+OxD1Hkw3Cdtu70m2Il6E3y+YWVO9IKzI+y66p7ot9 sx5f+NkuLlJnlgQS1lDSjn723VZKqFNb1cIDbLDg6uELIhv+7/d7eDchIM/SshrGAP1N AY2w== X-Gm-Message-State: AOAM531FbPRzN5fpgZ0F22rsFvQPlfDQ5cVWLbGCtii4c13NaZlZYE6W 0efQNn5UGUSsZVpHlM5RsB9oOT0d+t28 X-Google-Smtp-Source: ABdhPJwYF1kawNqVseiO7m27DBt/cqs+ne+QGTzIFChBVKDCqpuIaX8cdJTaoOjN8Cv37L+XEUkjHTj8iQJH X-Received: from bgardon.sea.corp.google.com ([2620:15c:100:202:b76a:f152:cb5e:5cd2]) (user=bgardon job=sendgmr) by 2002:a17:90a:1b2e:b0:1c6:d5ed:3ca4 with SMTP id q43-20020a17090a1b2e00b001c6d5ed3ca4mr1678022pjq.171.1647906555633; Mon, 21 Mar 2022 16:49:15 -0700 (PDT) Date: Mon, 21 Mar 2022 16:48:42 -0700 In-Reply-To: <20220321234844.1543161-1-bgardon@google.com> Message-Id: <20220321234844.1543161-10-bgardon@google.com> Mime-Version: 1.0 References: <20220321234844.1543161-1-bgardon@google.com> X-Mailer: git-send-email 2.35.1.894.gb6a874cedc-goog Subject: [PATCH v2 09/11] KVM: x86/MMU: Allow NX huge pages to be disabled on a per-vm basis 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 In some cases, the NX hugepage mitigation for iTLB multihit is not needed for all guests on a host. Allow disabling the mitigation on a per-VM basis to avoid the performance hit of NX hugepages on trusted workloads. Signed-off-by: Ben Gardon --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/mmu.h | 1 + arch/x86/kvm/mmu/mmu.c | 6 ++++-- arch/x86/kvm/x86.c | 6 ++++++ include/uapi/linux/kvm.h | 1 + 5 files changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0a0c54639dd8..04ddfc475ce0 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1242,6 +1242,7 @@ struct kvm_arch { #endif bool nx_huge_pages; + bool disable_nx_huge_pages; }; struct kvm_vm_stat { diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h index dd28fe8d13ae..36d8d84ca6c6 100644 --- a/arch/x86/kvm/mmu.h +++ b/arch/x86/kvm/mmu.h @@ -177,6 +177,7 @@ static inline bool is_nx_huge_page_enabled(struct kvm *kvm) { return READ_ONCE(kvm->arch.nx_huge_pages); } +void kvm_update_nx_huge_pages(struct kvm *kvm); static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u32 err, bool prefetch) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index dc9672f70468..a7d387ccfd74 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6195,9 +6195,10 @@ static void __set_nx_huge_pages(bool val) nx_huge_pages = itlb_multihit_kvm_mitigation = val; } -static void kvm_update_nx_huge_pages(struct kvm *kvm) +void kvm_update_nx_huge_pages(struct kvm *kvm) { - kvm->arch.nx_huge_pages = nx_huge_pages; + kvm->arch.nx_huge_pages = nx_huge_pages && + !kvm->arch.disable_nx_huge_pages; mutex_lock(&kvm->slots_lock); kvm_mmu_zap_all_fast(kvm); @@ -6451,6 +6452,7 @@ int kvm_mmu_post_init_vm(struct kvm *kvm) int err; kvm->arch.nx_huge_pages = READ_ONCE(nx_huge_pages); + kvm->arch.disable_nx_huge_pages = false; err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0, "kvm-nx-lpage-recovery", &kvm->arch.nx_lpage_recovery_thread); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 51106d32f04e..73df90a6932b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4256,6 +4256,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_SYS_ATTRIBUTES: case KVM_CAP_VAPIC: case KVM_CAP_ENABLE_CAP: + case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES: r = 1; break; case KVM_CAP_EXIT_HYPERCALL: @@ -6048,6 +6049,11 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, } mutex_unlock(&kvm->lock); break; + case KVM_CAP_VM_DISABLE_NX_HUGE_PAGES: + kvm->arch.disable_nx_huge_pages = true; + kvm_update_nx_huge_pages(kvm); + r = 0; + break; default: r = -EINVAL; break; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index ee5cc9e2a837..6f9fa7ecfd1e 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1144,6 +1144,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_S390_MEM_OP_EXTENSION 211 #define KVM_CAP_PMU_CAPABILITY 212 #define KVM_CAP_DISABLE_QUIRKS2 213 +#define KVM_CAP_VM_DISABLE_NX_HUGE_PAGES 214 #ifdef KVM_CAP_IRQ_ROUTING