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 X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88D7CC4338F for ; Mon, 9 Aug 2021 10:53:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6D1A4610A7 for ; Mon, 9 Aug 2021 10:53:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234353AbhHIKyJ (ORCPT ); Mon, 9 Aug 2021 06:54:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:44830 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234389AbhHIKyJ (ORCPT ); Mon, 9 Aug 2021 06:54:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E80736103B; Mon, 9 Aug 2021 10:53:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1628506429; bh=fO79yYth00OAiDAqdnzQby98bCJ6sA1LXMCn6Wf413s=; h=Subject:To:Cc:From:Date:From; b=v8fvPVP76tnzT569BCAS6iQdYSAjipDGecAFZsZ8mGGzCKd6btqYWZ2TusiCCvCRr Dk39GrqqMu3BK4nnRFuKde5L3/JHScNyAXN1R9l+Za6P5BktGUXPRTNIfHl1wIHPxc Bu1nhrhM1R7VSXztcazSEPE6H8RvzLWfb6t0olJ8= Subject: FAILED: patch "[PATCH] KVM: SVM: Fix off-by-one indexing when nullifying last used" failed to apply to 4.19-stable tree To: seanjc@google.com, brijesh.singh@amd.com, pbonzini@redhat.com, thomas.lendacky@amd.com Cc: From: Date: Mon, 09 Aug 2021 12:53:47 +0200 Message-ID: <16285064275244@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 179c6c27bf487273652efc99acd3ba512a23c137 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 3 Aug 2021 09:27:46 -0700 Subject: [PATCH] KVM: SVM: Fix off-by-one indexing when nullifying last used SEV VMCB Use the raw ASID, not ASID-1, when nullifying the last used VMCB when freeing an SEV ASID. The consumer, pre_sev_run(), indexes the array by the raw ASID, thus KVM could get a false negative when checking for a different VMCB if KVM manages to reallocate the same ASID+VMCB combo for a new VM. Note, this cannot cause a functional issue _in the current code_, as pre_sev_run() also checks which pCPU last did VMRUN for the vCPU, and last_vmentry_cpu is initialized to -1 during vCPU creation, i.e. is guaranteed to mismatch on the first VMRUN. However, prior to commit 8a14fe4f0c54 ("kvm: x86: Move last_cpu into kvm_vcpu_arch as last_vmentry_cpu"), SVM tracked pCPU on its own and zero-initialized the last_cpu variable. Thus it's theoretically possible that older versions of KVM could miss a TLB flush if the first VMRUN is on pCPU0 and the ASID and VMCB exactly match those of a prior VM. Fixes: 70cd94e60c73 ("KVM: SVM: VMRUN should use associated ASID when SEV is enabled") Cc: Tom Lendacky Cc: Brijesh Singh Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 6710d9ee2e4b..4d0aba185412 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -189,7 +189,7 @@ static void sev_asid_free(struct kvm_sev_info *sev) for_each_possible_cpu(cpu) { sd = per_cpu(svm_data, cpu); - sd->sev_vmcbs[pos] = NULL; + sd->sev_vmcbs[sev->asid] = NULL; } mutex_unlock(&sev_bitmap_lock);