From nobody Sun Dec 14 08:04:33 2025 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 CE83EC00140 for ; Mon, 15 Aug 2022 18:16:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239515AbiHOSQj (ORCPT ); Mon, 15 Aug 2022 14:16:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59016 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233572AbiHOSPZ (ORCPT ); Mon, 15 Aug 2022 14:15:25 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B53532AE16; Mon, 15 Aug 2022 11:14:35 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6F7BEB8106E; Mon, 15 Aug 2022 18:14:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE1F4C433D7; Mon, 15 Aug 2022 18:14:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660587273; bh=AE1AKp4oa0qoGjpBEOHT5TP3oZSgBNWXFJoL9mwS8W0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u1qwhaMxenHdqr5/usJJd07fBFJL0k309Qs65L5VhVvQEL4YFr0YZT2QpYGOyCDM7 wckV91zCbbr3cEgHAvI5oVsHXuujqpd/BmRcI0f0C1Yyiauau0+lyB8lgAQKvlbc4N BeElyomZeSeKNmecfIYWkxCr9axCz+uav+P9sP3o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dave Young , Xiaoying Yan , David Woodhouse , Paolo Bonzini , "Dr . David Alan Gilbert" Subject: [PATCH 5.15 033/779] KVM: x86: revalidate steal time cache if MSR value changes Date: Mon, 15 Aug 2022 19:54:37 +0200 Message-Id: <20220815180338.649734971@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180337.130757997@linuxfoundation.org> References: <20220815180337.130757997@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Paolo Bonzini commit 901d3765fa804ce42812f1d5b1f3de2dfbb26723 upstream. Commit 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status", 2021-11-11) open coded the previous call to kvm_map_gfn, but in doing so it dropped the comparison between the cached guest physical address and the one in the MSR. This cause an incorrect cache hit if the guest modifies the steal time address while the memslots remain the same. This can happen with kexec, in which case the steal time data is written at the address used by the old kernel instead of the old one. While at it, rename the variable from gfn to gpa since it is a plain physical address and not a right-shifted one. Reported-by: Dave Young Reported-by: Xiaoying Yan Analyzed-by: Dr. David Alan Gilbert Cc: David Woodhouse Cc: stable@vger.kernel.org Fixes: 7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempt= ed status") Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3244,6 +3244,7 @@ static void record_steal_time(struct kvm struct gfn_to_hva_cache *ghc =3D &vcpu->arch.st.cache; struct kvm_steal_time __user *st; struct kvm_memslots *slots; + gpa_t gpa =3D vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; u64 steal; u32 version; =20 @@ -3261,13 +3262,12 @@ static void record_steal_time(struct kvm slots =3D kvm_memslots(vcpu->kvm); =20 if (unlikely(slots->generation !=3D ghc->generation || + gpa !=3D ghc->gpa || kvm_is_error_hva(ghc->hva) || !ghc->memslot)) { - gfn_t gfn =3D vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; - /* We rely on the fact that it fits in a single page. */ BUILD_BUG_ON((sizeof(*st) - 1) & KVM_STEAL_VALID_BITS); =20 - if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gfn, sizeof(*st)) || + if (kvm_gfn_to_hva_cache_init(vcpu->kvm, ghc, gpa, sizeof(*st)) || kvm_is_error_hva(ghc->hva) || !ghc->memslot) return; }