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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 1618DC2D0BF for ; Mon, 16 Dec 2019 17:58:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6208205ED for ; Mon, 16 Dec 2019 17:58:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519097; bh=1maL35+ZquCf70MslmyRiHUyARkU8TTCBEuiezVRX+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=pDcU+Qarn1pj/VYmNabsggvPsLnK1jHXh5bF4J5STKaLbd551xd4j1YwATOPQG9KR jssqckrgfBTD74ZGd4BgSvleZLZ791KFPJUz6ZfbB4Zu9T2v3247/S3hMB8VrUeXDz iN2KKFPCqsPOBp6xDkfGuG5aY1xIj0zUlNkgp7a4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728591AbfLPR6Q (ORCPT ); Mon, 16 Dec 2019 12:58:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:57736 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727433AbfLPR6L (ORCPT ); Mon, 16 Dec 2019 12:58:11 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4F8BB205ED; Mon, 16 Dec 2019 17:58:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576519090; bh=1maL35+ZquCf70MslmyRiHUyARkU8TTCBEuiezVRX+M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GFEp5hzvMckNP0n689wvPXT3WkFd4FvTlh4kmX2APXCuSyE1y8TOXj3QnRiTtQaLt 5ueR8SCrbGz9wXaLSuCVSfHwenQk4T9SFLziDTzFuirjPuEDtwgOhfLAuppA4ooCpW rKBZtYotdaOj7vuo9PQPTTud28ReXvZECBgh+R5E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jim Mattson , Paolo Bonzini Subject: [PATCH 4.14 141/267] KVM: x86: do not modify masked bits of shared MSRs Date: Mon, 16 Dec 2019 18:47:47 +0100 Message-Id: <20191216174910.207831723@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191216174848.701533383@linuxfoundation.org> References: <20191216174848.701533383@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo Bonzini commit de1fca5d6e0105c9d33924e1247e2f386efc3ece upstream. "Shared MSRs" are guest MSRs that are written to the host MSRs but keep their value until the next return to userspace. They support a mask, so that some bits keep the host value, but this mask is only used to skip an unnecessary MSR write and the value written to the MSR is always the guest MSR. Fix this and, while at it, do not update smsr->values[slot].curr if for whatever reason the wrmsr fails. This should only happen due to reserved bits, so the value written to smsr->values[slot].curr will not match when the user-return notifier and the host value will always be restored. However, it is untidy and in rare cases this can actually avoid spurious WRMSRs on return to userspace. Cc: stable@vger.kernel.org Reviewed-by: Jim Mattson Tested-by: Jim Mattson Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -276,13 +276,14 @@ int kvm_set_shared_msr(unsigned slot, u6 struct kvm_shared_msrs *smsr = per_cpu_ptr(shared_msrs, cpu); int err; - if (((value ^ smsr->values[slot].curr) & mask) == 0) + value = (value & mask) | (smsr->values[slot].host & ~mask); + if (value == smsr->values[slot].curr) return 0; - smsr->values[slot].curr = value; err = wrmsrl_safe(shared_msrs_global.msrs[slot], value); if (err) return 1; + smsr->values[slot].curr = value; if (!smsr->registered) { smsr->urn.on_user_return = kvm_on_user_return; user_return_notifier_register(&smsr->urn);