From patchwork Thu Nov 4 00:25:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12602015 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9803C4332F for ; Thu, 4 Nov 2021 00:27:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B57E060F9D for ; Thu, 4 Nov 2021 00:27:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232755AbhKDA3u (ORCPT ); Wed, 3 Nov 2021 20:29:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233116AbhKDA2i (ORCPT ); Wed, 3 Nov 2021 20:28:38 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1354AC061714 for ; Wed, 3 Nov 2021 17:26:01 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id n22-20020a6563d6000000b0029261ffde9bso2347267pgv.22 for ; Wed, 03 Nov 2021 17:26:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=+lV0XpIZU6tw19BsegMK11Am0XrNm95tEDZ+cjWdUrM=; b=jbtShP55MKCx20McDFEhvtwsoRH1khB6gzD/3j56rgiZ3zt1jHh02awL7RkCEzV3OS juVR4kJgynHQLk53v8qOxVTOjp/cr1Axpeb38StAvaM6K/Esi65OU9b5Xxj4BlHERFw/ 20Ros746PIesTfL4lqUBcYH1DmBdILCibzAzE0JyxJqshteAL/za33QXIkiltJhs6fgG bVtI7QJVCXpF8HJS0rKZ95KbFtPX72tTwq3ga0tOCYx8FS5o3uLhWSoZiizq/DCYGBRC nP9YYyqmezSHN3kgANHiJKtWGLbMgy/F9P8mC6PT1O/nqJH2RcSpIBmpTyxPG6DF1Hbi bVTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=+lV0XpIZU6tw19BsegMK11Am0XrNm95tEDZ+cjWdUrM=; b=0RTK18Bw/rCAfhBNugLTVgEiEaggHvTsLkdfce+4Wnkfu3t4LtL6mvSEmILyhNXbx3 XAv+H8HHEGgqRvQLm1+Pwv53klw1m82iMBpPqxihcDCkFbqSZd73IFqXyfWuAmxp3tnE GdWNw08l0Cn8dYTxm/oxrmUd3wMsIldfWKG66aU3EF0ic3jxB9rKAgPrZszv4yZUZ4Tw Ce+VDw7l0Vtx+JgyhjDIeE2HtOlHj7eoqjDBFxh0207GXYCSKt3nl6NZjOzNsA3y7IN+ JLsbLBr4V09o6M5N3dKw1vy6aRg07lMYts3hZLb2WHT8edj6O4WWyPe3RgXOMA3NNKbf 0yaA== X-Gm-Message-State: AOAM532BNqw2rJLjSdka7q1UvSvF4Bn5a1wR/slVgoZGHMsoY9we8r8Y I2QLdOZnR42Oc1kW91y7pvLWjK78COI= X-Google-Smtp-Source: ABdhPJxPA9GZBaEM5Ul3kt/1JljrZJu3YLRnIzyzQ/7OAn8VgQo/7agz4e2n8dYIb/fDnOKKBTJDQWAH1V8= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:90a:c3:: with SMTP id v3mr252263pjd.0.1635985559868; Wed, 03 Nov 2021 17:25:59 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 4 Nov 2021 00:25:02 +0000 In-Reply-To: <20211104002531.1176691-1-seanjc@google.com> Message-Id: <20211104002531.1176691-2-seanjc@google.com> Mime-Version: 1.0 References: <20211104002531.1176691-1-seanjc@google.com> X-Mailer: git-send-email 2.33.1.1089.g2158813163f-goog Subject: [PATCH v5.5 01/30] KVM: Ensure local memslot copies operate on up-to-date arch-specific data From: Sean Christopherson To: Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Ben Gardon , "Maciej S . Szmigiero" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org When modifying memslots, snapshot the "old" memslot and copy it to the "new" memslot's arch data after (re)acquiring slots_arch_lock. x86 can change a memslot's arch data while memslot updates are in-progress so long as it holds slots_arch_lock, thus snapshotting a memslot without holding the lock can result in the consumption of stale data. Fixes: b10a038e84d1 ("KVM: mmu: Add slots_arch_lock for memslot arch fields") Cc: stable@vger.kernel.org Cc: Ben Gardon Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 47 ++++++++++++++++++++++++++++++--------------- 1 file changed, 31 insertions(+), 16 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3f6d450355f0..99e69375c4c9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1531,11 +1531,10 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old, static int kvm_set_memslot(struct kvm *kvm, const struct kvm_userspace_memory_region *mem, - struct kvm_memory_slot *old, struct kvm_memory_slot *new, int as_id, enum kvm_mr_change change) { - struct kvm_memory_slot *slot; + struct kvm_memory_slot *slot, old; struct kvm_memslots *slots; int r; @@ -1566,7 +1565,7 @@ static int kvm_set_memslot(struct kvm *kvm, * Note, the INVALID flag needs to be in the appropriate entry * in the freshly allocated memslots, not in @old or @new. */ - slot = id_to_memslot(slots, old->id); + slot = id_to_memslot(slots, new->id); slot->flags |= KVM_MEMSLOT_INVALID; /* @@ -1597,6 +1596,26 @@ static int kvm_set_memslot(struct kvm *kvm, kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id)); } + /* + * Make a full copy of the old memslot, the pointer will become stale + * when the memslots are re-sorted by update_memslots(), and the old + * memslot needs to be referenced after calling update_memslots(), e.g. + * to free its resources and for arch specific behavior. This needs to + * happen *after* (re)acquiring slots_arch_lock. + */ + slot = id_to_memslot(slots, new->id); + if (slot) { + old = *slot; + } else { + WARN_ON_ONCE(change != KVM_MR_CREATE); + memset(&old, 0, sizeof(old)); + old.id = new->id; + old.as_id = as_id; + } + + /* Copy the arch-specific data, again after (re)acquiring slots_arch_lock. */ + memcpy(&new->arch, &old.arch, sizeof(old.arch)); + r = kvm_arch_prepare_memory_region(kvm, new, mem, change); if (r) goto out_slots; @@ -1604,14 +1623,18 @@ static int kvm_set_memslot(struct kvm *kvm, update_memslots(slots, new, change); slots = install_new_memslots(kvm, as_id, slots); - kvm_arch_commit_memory_region(kvm, mem, old, new, change); + kvm_arch_commit_memory_region(kvm, mem, &old, new, change); + + /* Free the old memslot's metadata. Note, this is the full copy!!! */ + if (change == KVM_MR_DELETE) + kvm_free_memslot(kvm, &old); kvfree(slots); return 0; out_slots: if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) { - slot = id_to_memslot(slots, old->id); + slot = id_to_memslot(slots, new->id); slot->flags &= ~KVM_MEMSLOT_INVALID; slots = install_new_memslots(kvm, as_id, slots); } else { @@ -1626,7 +1649,6 @@ static int kvm_delete_memslot(struct kvm *kvm, struct kvm_memory_slot *old, int as_id) { struct kvm_memory_slot new; - int r; if (!old->npages) return -EINVAL; @@ -1639,12 +1661,7 @@ static int kvm_delete_memslot(struct kvm *kvm, */ new.as_id = as_id; - r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE); - if (r) - return r; - - kvm_free_memslot(kvm, old); - return 0; + return kvm_set_memslot(kvm, mem, &new, as_id, KVM_MR_DELETE); } /* @@ -1718,7 +1735,6 @@ int __kvm_set_memory_region(struct kvm *kvm, if (!old.npages) { change = KVM_MR_CREATE; new.dirty_bitmap = NULL; - memset(&new.arch, 0, sizeof(new.arch)); } else { /* Modify an existing slot. */ if ((new.userspace_addr != old.userspace_addr) || (new.npages != old.npages) || @@ -1732,9 +1748,8 @@ int __kvm_set_memory_region(struct kvm *kvm, else /* Nothing to change. */ return 0; - /* Copy dirty_bitmap and arch from the current memslot. */ + /* Copy dirty_bitmap from the current memslot. */ new.dirty_bitmap = old.dirty_bitmap; - memcpy(&new.arch, &old.arch, sizeof(new.arch)); } if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) { @@ -1760,7 +1775,7 @@ int __kvm_set_memory_region(struct kvm *kvm, bitmap_set(new.dirty_bitmap, 0, new.npages); } - r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change); + r = kvm_set_memslot(kvm, mem, &new, as_id, change); if (r) goto out_bitmap;