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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57B20C433F5 for ; Sat, 20 Nov 2021 10:16:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237291AbhKTKT7 (ORCPT ); Sat, 20 Nov 2021 05:19:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230503AbhKTKT5 (ORCPT ); Sat, 20 Nov 2021 05:19:57 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CA3CC061574; Sat, 20 Nov 2021 02:16:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=O7jwwKuWTgvseH8YRxnLk6vqt2eMEY4vcYCD3qhW44c=; b=f+BoFEsW1VZBgyKf1Ow9VDxfMN V7JGiYjyw3GlqK4oDM1L1dNLK9g6NWFgA0CePgEIGmrCQoMVw/nw5ITUh21Lo7VVycbbNH2Ym8zm7 HA6Y6uZayDl8PpmARvlFQgRtihAhg2JZ07sBqVAIckrky79DclazDOfYt7sU7xEaHG+UPcys9Q8Vx UnDufSMTsPWxbKLH+Rdf9VNoMq9+RbsMTi6gqlFAgsGh070y8Y2ZzVHc25OgU3wgwmStOyKTPBHuc MT+eezofrSQWec/o0jiYJofTRdTK6lTNHMcrwdzMvNSROZxXFI0hZB8M43O/cZL8U4tvoMVLOTPlM vhEO5SYw==; Received: from [2001:8b0:10b:1:4a2a:e3ff:fe14:8625] (helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1moNQR-00CGNA-Fy; Sat, 20 Nov 2021 10:16:51 +0000 Message-ID: Subject: KVM: Warn if mark_page_dirty() is called without an active vCPU From: David Woodhouse To: Paolo Bonzini , butt3rflyh4ck Cc: kvm@vger.kernel.org, LKML , Sean Christopherson Date: Sat, 20 Nov 2021 10:16:49 +0000 In-Reply-To: <9eb83cdd-9314-0d1f-0d4b-0cf4432e1e84@redhat.com> References: <9eb83cdd-9314-0d1f-0d4b-0cf4432e1e84@redhat.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-gV6V4eG/xzlrObPRQMXm" User-Agent: Evolution 3.36.5-0ubuntu1 MIME-Version: 1.0 X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-gV6V4eG/xzlrObPRQMXm Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable From: David Woodhouse The various kvm_write_guest() and mark_page_dirty() functions must only ever be called in the context of an active vCPU, because if dirty ring tracking is enabled it may simply oops when kvm_get_running_vcpu() returns NULL for the vcpu and then kvm_dirty_ring_get() dereferences it. This oops was reported by "butt3rflyh4ck" in https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5u= G94g@mail.gmail.com/ That actual bug will be fixed under separate cover but this warning should help to prevent new ones from being added. Signed-off-by: David Woodhouse --- include/linux/kvm_dirty_ring.h | 6 ------ virt/kvm/dirty_ring.c | 9 --------- virt/kvm/kvm_main.c | 7 ++++++- 3 files changed, 6 insertions(+), 16 deletions(-) diff --git a/include/linux/kvm_dirty_ring.h b/include/linux/kvm_dirty_ring.= h index 120e5e90fa1d..fb0fa18878e2 100644 --- a/include/linux/kvm_dirty_ring.h +++ b/include/linux/kvm_dirty_ring.h @@ -43,11 +43,6 @@ static inline int kvm_dirty_ring_alloc(struct kvm_dirty_= ring *ring, return 0; } =20 -static inline struct kvm_dirty_ring *kvm_dirty_ring_get(struct kvm *kvm) -{ - return NULL; -} - static inline int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring) { @@ -78,7 +73,6 @@ static inline bool kvm_dirty_ring_soft_full(struct kvm_di= rty_ring *ring) =20 u32 kvm_dirty_ring_get_rsvd_entries(void); int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring, int index, u32 size)= ; -struct kvm_dirty_ring *kvm_dirty_ring_get(struct kvm *kvm); =20 /* * called with kvm->slots_lock held, returns the number of diff --git a/virt/kvm/dirty_ring.c b/virt/kvm/dirty_ring.c index 88f4683198ea..8e9874760fb3 100644 --- a/virt/kvm/dirty_ring.c +++ b/virt/kvm/dirty_ring.c @@ -36,15 +36,6 @@ static bool kvm_dirty_ring_full(struct kvm_dirty_ring *r= ing) return kvm_dirty_ring_used(ring) >=3D ring->size; } =20 -struct kvm_dirty_ring *kvm_dirty_ring_get(struct kvm *kvm) -{ - struct kvm_vcpu *vcpu =3D kvm_get_running_vcpu(); - - WARN_ON_ONCE(vcpu->kvm !=3D kvm); - - return &vcpu->dirty_ring; -} - static void kvm_reset_dirty_gfn(struct kvm *kvm, u32 slot, u64 offset, u64= mask) { struct kvm_memory_slot *memslot; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 6c5083f2eb50..72c6453bcef4 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3020,12 +3020,17 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot, gfn_t gfn) { + struct kvm_vcpu *vcpu =3D kvm_get_running_vcpu(); + + if (WARN_ON_ONCE(!vcpu) || WARN_ON_ONCE(vcpu->kvm !=3D kvm)) + return; + if (memslot && kvm_slot_dirty_track_enabled(memslot)) { unsigned long rel_gfn =3D gfn - memslot->base_gfn; u32 slot =3D (memslot->as_id << 16) | memslot->id; =20 if (kvm->dirty_ring_size) - kvm_dirty_ring_push(kvm_dirty_ring_get(kvm), + kvm_dirty_ring_push(&vcpu->dirty_ring, slot, rel_gfn); else set_bit_le(rel_gfn, memslot->dirty_bitmap); --=20 2.31.1 --=-gV6V4eG/xzlrObPRQMXm Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B 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