From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCA14C43460 for ; Mon, 17 May 2021 14:39:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4D1D61CEF for ; Mon, 17 May 2021 14:39:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240020AbhEQOlG (ORCPT ); Mon, 17 May 2021 10:41:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:37396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240515AbhEQOiP (ORCPT ); Mon, 17 May 2021 10:38:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0F90461415; Mon, 17 May 2021 14:18:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621261093; bh=M3ImQpsI4qgr16PpwL6GD8l8WZpsbWfieH0Y/njWdFA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V/nkyVw9uczYYs4VXzQBCGdKPG0u7Vig9kF0S9Cl3M/KTpxceVHK2/WJkccsSMdFv kINXFmpZu3WcLmxEef5E1MAxWhN2YVEy77BvPUZR89sVUJRpAezVE9Z4v/BG32y0oK le04uCxM87nJzBgs3xe9B6RPvdmoFRDFH9lGLZq4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yu Zhang , Sean Christopherson , Paolo Bonzini , Jack Wang Subject: [PATCH 5.4 004/141] KVM: x86/mmu: Remove the defunct update_pte() paging hook Date: Mon, 17 May 2021 16:00:56 +0200 Message-Id: <20210517140242.903613120@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140242.729269392@linuxfoundation.org> References: <20210517140242.729269392@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sean Christopherson commit c5e2184d1544f9e56140791eff1a351bea2e63b9 upstream. Remove the update_pte() shadow paging logic, which was obsoleted by commit 4731d4c7a077 ("KVM: MMU: out of sync shadow core"), but never removed. As pointed out by Yu, KVM never write protects leaf page tables for the purposes of shadow paging, and instead marks their associated shadow page as unsync so that the guest can write PTEs at will. The update_pte() path, which predates the unsync logic, optimizes COW scenarios by refreshing leaf SPTEs when they are written, as opposed to zapping the SPTE, restarting the guest, and installing the new SPTE on the subsequent fault. Since KVM no longer write-protects leaf page tables, update_pte() is unreachable and can be dropped. Reported-by: Yu Zhang Signed-off-by: Sean Christopherson Message-Id: <20210115004051.4099250-1-seanjc@google.com> Signed-off-by: Paolo Bonzini (jwang: backport to 5.4 to fix a warning on AMD nested Virtualization) Signed-off-by: Jack Wang Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/kvm_host.h | 3 --- arch/x86/kvm/mmu.c | 33 ++------------------------------- arch/x86/kvm/x86.c | 1 - 3 files changed, 2 insertions(+), 35 deletions(-) --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -391,8 +391,6 @@ struct kvm_mmu { int (*sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp); void (*invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa); - void (*update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, - u64 *spte, const void *pte); hpa_t root_hpa; gpa_t root_cr3; union kvm_mmu_role mmu_role; @@ -944,7 +942,6 @@ struct kvm_arch { struct kvm_vm_stat { ulong mmu_shadow_zapped; ulong mmu_pte_write; - ulong mmu_pte_updated; ulong mmu_pde_zapped; ulong mmu_flooded; ulong mmu_recycled; --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2243,13 +2243,6 @@ static void nonpaging_invlpg(struct kvm_ { } -static void nonpaging_update_pte(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp, u64 *spte, - const void *pte) -{ - WARN_ON(1); -} - #define KVM_PAGE_ARRAY_NR 16 struct kvm_mmu_pages { @@ -4356,7 +4349,6 @@ static void nonpaging_init_context(struc context->gva_to_gpa = nonpaging_gva_to_gpa; context->sync_page = nonpaging_sync_page; context->invlpg = nonpaging_invlpg; - context->update_pte = nonpaging_update_pte; context->root_level = 0; context->shadow_root_level = PT32E_ROOT_LEVEL; context->direct_map = true; @@ -4935,7 +4927,6 @@ static void paging64_init_context_common context->gva_to_gpa = paging64_gva_to_gpa; context->sync_page = paging64_sync_page; context->invlpg = paging64_invlpg; - context->update_pte = paging64_update_pte; context->shadow_root_level = level; context->direct_map = false; } @@ -4964,7 +4955,6 @@ static void paging32_init_context(struct context->gva_to_gpa = paging32_gva_to_gpa; context->sync_page = paging32_sync_page; context->invlpg = paging32_invlpg; - context->update_pte = paging32_update_pte; context->shadow_root_level = PT32E_ROOT_LEVEL; context->direct_map = false; } @@ -5039,7 +5029,6 @@ static void init_kvm_tdp_mmu(struct kvm_ context->page_fault = tdp_page_fault; context->sync_page = nonpaging_sync_page; context->invlpg = nonpaging_invlpg; - context->update_pte = nonpaging_update_pte; context->shadow_root_level = kvm_x86_ops->get_tdp_level(vcpu); context->direct_map = true; context->set_cr3 = kvm_x86_ops->set_tdp_cr3; @@ -5172,7 +5161,6 @@ void kvm_init_shadow_ept_mmu(struct kvm_ context->gva_to_gpa = ept_gva_to_gpa; context->sync_page = ept_sync_page; context->invlpg = ept_invlpg; - context->update_pte = ept_update_pte; context->root_level = PT64_ROOT_4LEVEL; context->direct_map = false; context->mmu_role.as_u64 = new_role.as_u64; @@ -5312,19 +5300,6 @@ void kvm_mmu_unload(struct kvm_vcpu *vcp } EXPORT_SYMBOL_GPL(kvm_mmu_unload); -static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp, u64 *spte, - const void *new) -{ - if (sp->role.level != PT_PAGE_TABLE_LEVEL) { - ++vcpu->kvm->stat.mmu_pde_zapped; - return; - } - - ++vcpu->kvm->stat.mmu_pte_updated; - vcpu->arch.mmu->update_pte(vcpu, sp, spte, new); -} - static bool need_remote_flush(u64 old, u64 new) { if (!is_shadow_present_pte(old)) @@ -5490,14 +5465,10 @@ static void kvm_mmu_pte_write(struct kvm local_flush = true; while (npte--) { - u32 base_role = vcpu->arch.mmu->mmu_role.base.word; - entry = *spte; mmu_page_zap_pte(vcpu->kvm, sp, spte); - if (gentry && - !((sp->role.word ^ base_role) - & mmu_base_role_mask.word) && rmap_can_add(vcpu)) - mmu_pte_write_new_pte(vcpu, sp, spte, &gentry); + if (gentry && sp->role.level != PG_LEVEL_4K) + ++vcpu->kvm->stat.mmu_pde_zapped; if (need_remote_flush(entry, *spte)) remote_flush = true; ++spte; --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -208,7 +208,6 @@ struct kvm_stats_debugfs_item debugfs_en { "l1d_flush", VCPU_STAT(l1d_flush) }, { "mmu_shadow_zapped", VM_STAT(mmu_shadow_zapped) }, { "mmu_pte_write", VM_STAT(mmu_pte_write) }, - { "mmu_pte_updated", VM_STAT(mmu_pte_updated) }, { "mmu_pde_zapped", VM_STAT(mmu_pde_zapped) }, { "mmu_flooded", VM_STAT(mmu_flooded) }, { "mmu_recycled", VM_STAT(mmu_recycled) },