From patchwork Mon Mar 14 11:54:08 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 551628 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 D6D3DC41535 for ; Mon, 14 Mar 2022 12:22:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241486AbiCNMWw (ORCPT ); Mon, 14 Mar 2022 08:22:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243644AbiCNMVG (ORCPT ); Mon, 14 Mar 2022 08:21:06 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D13E354FB5; Mon, 14 Mar 2022 05:16:33 -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 6766B60C77; Mon, 14 Mar 2022 12:16:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BE79C340E9; Mon, 14 Mar 2022 12:16:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1647260192; bh=q6225OgmNK7kllOTZPGgFL9ixZv/nU3ERVzIB1tEN58=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TIQPeqLDBZqh1IKZAK9dFGSyYgbxaIvTCIr/GITR48vixGd61wNdBi2eiRtR35xfZ +IpJFL/WsDJ0xfZjYum7j+3/EjNX1upD3g65xthIm9lc0S2mhnOGa3x6f4xSjFp+9Z UHCotToxd1MhHzftvnw6gjR3kocB6xsGOLXVRjzU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Anton Romanov , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.16 065/121] kvm: x86: Disable KVM_HC_CLOCK_PAIRING if tsc is in always catchup mode Date: Mon, 14 Mar 2022 12:54:08 +0100 Message-Id: <20220314112745.939591232@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220314112744.120491875@linuxfoundation.org> References: <20220314112744.120491875@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Anton Romanov [ Upstream commit 3a55f729240a686aa8af00af436306c0cd532522 ] If vcpu has tsc_always_catchup set each request updates pvclock data. KVM_HC_CLOCK_PAIRING consumers such as ptp_kvm_x86 rely on tsc read on host's side and do hypercall inside pvclock_read_retry loop leading to infinite loop in such situation. v3: Removed warn Changed return code to KVM_EFAULT v2: Added warn Signed-off-by: Anton Romanov Message-Id: <20220216182653.506850-1-romanton@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/x86.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c6eb3e45e3d8..e8f495b9ae10 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8770,6 +8770,13 @@ static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr, if (clock_type != KVM_CLOCK_PAIRING_WALLCLOCK) return -KVM_EOPNOTSUPP; + /* + * When tsc is in permanent catchup mode guests won't be able to use + * pvclock_read_retry loop to get consistent view of pvclock + */ + if (vcpu->arch.tsc_always_catchup) + return -KVM_EOPNOTSUPP; + if (!kvm_get_walltime_and_clockread(&ts, &cycle)) return -KVM_EOPNOTSUPP;