From nobody Fri Feb 13 19:29:07 2026 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 26BB2E7D0AA for ; Thu, 21 Sep 2023 20:56:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230381AbjIUU4f (ORCPT ); Thu, 21 Sep 2023 16:56:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232507AbjIUU4L (ORCPT ); Thu, 21 Sep 2023 16:56:11 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86AF6C06B5 for ; Thu, 21 Sep 2023 13:33:44 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id d9443c01a7336-1c43e6ba8d1so10908555ad.3 for ; Thu, 21 Sep 2023 13:33:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1695328424; x=1695933224; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=ooFkuvOD+X01OBgJAJRWL8fBqVSu8Kag+d9BzvqrsOA=; b=V30WBHyn02jX7zrORwjVf/opgyfac0giuBab24z168ORR6RfjRU3+sdMlHIDUzp6+Q GEFaeOzRwqrZDztBXnfHO4WJ8PkuAwHRZinBGYE3zKGTKo2Fb+osioFKh6xktbut6JTT 5ynF5OnJLijZqWSQWpzsG4qhYQ06o2LkcCz/Brn7eDPGdhiSzX1TBsIOHTlup6XkvLh/ ZBlRZpGCWG2Uz2L+ElIrKAu/HXtFlQV8ZBxI7qUE/E/K1KLk38MMM4Pmn7yY9f1/j9x6 OYiH9wJVoKsWGfHjMGWYDqyXeKIPoEzZ6StluXAYO+lY+Ryyo4Pr/UHTRWHDZ0xLmJyJ iaJw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695328424; x=1695933224; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ooFkuvOD+X01OBgJAJRWL8fBqVSu8Kag+d9BzvqrsOA=; b=lnmYcXHI8RjOe8JNCfO+gm24DjzIb+7HEZ2KfF/ztyectMq6ZghfurPFqBBGx99HbO +fdfkuZud2VQeABOhjVHzDcGRTV0k+epVm7pFLXsyERZaF+QpAIPrwhLyJ3eH/MNs6Wj zkmKjJGSSiU7lAfSqdbRLgutZNqJlH4n+GYm8pnWMYfMNTX2PxkwdjS7Lhs22JleksfM 2VkPebj/PbS7IaFy2B2Qa6fOTL7blBmYWk3tssT+8aQcKgTcQnKipeL9ZJB3d3rQ/EMF /qm4/N5EuFCwHdk4xqUkOMLdkcHS8/DjZM9DlOib8nYB0E0HgUaDdmJmJFBO+jemb8Y8 kNGQ== X-Gm-Message-State: AOJu0YzpOYg4+0A42TnQ7fbGOqQVpSQtYUnpr4GwGW5Th6zaCbNwhabX 4L9PxI9hKtH1jDkyWBoeV+r4KFmlK30= X-Google-Smtp-Source: AGHT+IEU5m4YoGaLYARxz6CkyfsMJNbrUD8SUx5Ubkh7a53+UYT0k7pUszgIuGSWr5rg40lyfuo4qcQeNaM= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:e5d2:b0:1bf:cc5:7b53 with SMTP id u18-20020a170902e5d200b001bf0cc57b53mr91087plf.1.1695328423673; Thu, 21 Sep 2023 13:33:43 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 21 Sep 2023 13:33:22 -0700 In-Reply-To: <20230921203331.3746712-1-seanjc@google.com> Mime-Version: 1.0 References: <20230921203331.3746712-1-seanjc@google.com> X-Mailer: git-send-email 2.42.0.515.g380fc7ccd1-goog Message-ID: <20230921203331.3746712-6-seanjc@google.com> Subject: [PATCH 05/13] KVM: Fix MMU invalidation bookkeeping in guest_memfd From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Roth , Binbin Wu Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Acquire mmu_lock and do invalidate_{begin,end}() if and only if there is at least one memslot that overlaps the to-be-invalidated range. This fixes a bug where KVM would leave a danging in-progress invalidation as the begin() call was unconditional, but the end() was not (only performed if there was overlap). Reported-by: Binbin Wu Fixes: 1d46f95498c5 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-spe= cific backing memory") Signed-off-by: Sean Christopherson --- virt/kvm/guest_mem.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c index 3c9e83a596fe..68528e9cddd7 100644 --- a/virt/kvm/guest_mem.c +++ b/virt/kvm/guest_mem.c @@ -88,14 +88,10 @@ static struct folio *kvm_gmem_get_folio(struct inode *i= node, pgoff_t index) static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start, pgoff_t end) { + bool flush =3D false, found_memslot =3D false; struct kvm_memory_slot *slot; struct kvm *kvm =3D gmem->kvm; unsigned long index; - bool flush =3D false; - - KVM_MMU_LOCK(kvm); - - kvm_mmu_invalidate_begin(kvm); =20 xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) { pgoff_t pgoff =3D slot->gmem.pgoff; @@ -107,13 +103,21 @@ static void kvm_gmem_invalidate_begin(struct kvm_gmem= *gmem, pgoff_t start, .may_block =3D true, }; =20 + if (!found_memslot) { + found_memslot =3D true; + + KVM_MMU_LOCK(kvm); + kvm_mmu_invalidate_begin(kvm); + } + flush |=3D kvm_mmu_unmap_gfn_range(kvm, &gfn_range); } =20 if (flush) kvm_flush_remote_tlbs(kvm); =20 - KVM_MMU_UNLOCK(kvm); + if (found_memslot) + KVM_MMU_UNLOCK(kvm); } =20 static void kvm_gmem_invalidate_end(struct kvm_gmem *gmem, pgoff_t start, @@ -121,10 +125,11 @@ static void kvm_gmem_invalidate_end(struct kvm_gmem *= gmem, pgoff_t start, { struct kvm *kvm =3D gmem->kvm; =20 - KVM_MMU_LOCK(kvm); - if (xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) + if (xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) { + KVM_MMU_LOCK(kvm); kvm_mmu_invalidate_end(kvm); - KVM_MMU_UNLOCK(kvm); + KVM_MMU_UNLOCK(kvm); + } } =20 static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t= len) --=20 2.42.0.515.g380fc7ccd1-goog