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 40203C2BB41 for ; Mon, 15 Aug 2022 20:17:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239413AbiHOUQ7 (ORCPT ); Mon, 15 Aug 2022 16:16:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242804AbiHOUJd (ORCPT ); Mon, 15 Aug 2022 16:09:33 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0A2A83F27; Mon, 15 Aug 2022 11:56:03 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 7875661269; Mon, 15 Aug 2022 18:56:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F037C4347C; Mon, 15 Aug 2022 18:56:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660589762; bh=UerYEdi2BJaXW/viwnJ9EWi8N9rrZIUY1Zl3yZjqTMw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xtM2EoDcPxlpiJBxlcfAJt2TpdmAjdefOWTu0/oZWlbDhAzot8DFdW/2L5YdnuFK2 Rq9JadkfRu39xe3dXgpk2y7dwZXTUI2ieD7jeh6ryVx7NlErEzJrCVXmz0+tzV5dXA VVG9KhxTi8yQaqZtwm2Dr4I8ZH07ZHDV8nNDyPIY= 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 5.18 0041/1095] KVM: x86: revalidate steal time cache if MSR value changes Date: Mon, 15 Aug 2022 19:50:40 +0200 Message-Id: <20220815180431.127649155@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180429.240518113@linuxfoundation.org> References: <20220815180429.240518113@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 / preempted 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 @@ -3367,6 +3367,7 @@ static void record_steal_time(struct kvm struct gfn_to_hva_cache *ghc = &vcpu->arch.st.cache; struct kvm_steal_time __user *st; struct kvm_memslots *slots; + gpa_t gpa = vcpu->arch.st.msr_val & KVM_STEAL_VALID_BITS; u64 steal; u32 version; @@ -3384,13 +3385,12 @@ static void record_steal_time(struct kvm slots = kvm_memslots(vcpu->kvm); if (unlikely(slots->generation != ghc->generation || + gpa != ghc->gpa || kvm_is_error_hva(ghc->hva) || !ghc->memslot)) { - gfn_t gfn = 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); - 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; }