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=-9.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 634C6C433E0 for ; Thu, 23 Jul 2020 03:11:28 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2B8F620657 for ; Thu, 23 Jul 2020 03:11:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=gibson.dropbear.id.au header.i=@gibson.dropbear.id.au header.b="gXyYB4f4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B8F620657 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gibson.dropbear.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:60282 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jyRdn-00017C-EH for qemu-devel@archiver.kernel.org; Wed, 22 Jul 2020 23:11:27 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39746) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyRbF-0006IC-3k; Wed, 22 Jul 2020 23:08:49 -0400 Received: from bilbo.ozlabs.org ([2401:3900:2:1::2]:59779 helo=ozlabs.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jyRbB-0006T9-1b; Wed, 22 Jul 2020 23:08:48 -0400 Received: by ozlabs.org (Postfix, from userid 1007) id 4BBy2v4wbGz9sSJ; Thu, 23 Jul 2020 13:08:39 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gibson.dropbear.id.au; s=201602; t=1595473719; bh=SuFKnJtCX3Fir48Plm6JLHASs5M1Y7sRHGO+Nub+nCk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gXyYB4f4zZemW/JvVg618Yfl0Vh9m40E4hpkjwLLN7Ze+vJWjHrID6hY8srmQBcfI pq03WecoTTmpqSgCGRJ7iX55AjwXmaLOa662feRF6iCeUPuuDxlgCsvXS7OXdplKtF j57YtXZ6fsKr4N6Li9yL9FWTpzIsdnm5lCRV/bzU= Date: Thu, 23 Jul 2020 13:06:51 +1000 From: David Gibson To: Thiago Jung Bauermann Subject: Re: [PATCH v3 3/8] ppc/spapr: Use start-powered-off CPUState property Message-ID: <20200723030651.GN5513@umbus.fritz.box> References: <20200723025657.644724-1-bauerman@linux.ibm.com> <20200723025657.644724-4-bauerman@linux.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="WeDu0lr7bteb/II5" Content-Disposition: inline In-Reply-To: <20200723025657.644724-4-bauerman@linux.ibm.com> Received-SPF: pass client-ip=2401:3900:2:1::2; envelope-from=dgibson@ozlabs.org; helo=ozlabs.org X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -9 X-Spam_score: -1.0 X-Spam_bar: - X-Spam_report: (-1.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Aleksandar Rikalo , Eduardo Habkost , Aleksandar Markovic , Alex =?iso-8859-1?Q?Benn=E9e?= , Cornelia Huck , Mark Cave-Ayland , qemu-devel@nongnu.org, Greg Kurz , qemu-s390x@nongnu.org, qemu-arm@nongnu.org, qemu-ppc@nongnu.org, Artyom Tarasenko , Thomas Huth , Paolo Bonzini , David Hildenbrand , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --WeDu0lr7bteb/II5 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 22, 2020 at 11:56:52PM -0300, Thiago Jung Bauermann wrote: 65;6003;1c> PowerPC sPAPR CPUs start in the halted state, and spapr_reset_v= cpu() > attempts to implement this by setting CPUState::halted to 1. But that's t= oo > late for the case of hotplugged CPUs in a machine configure with 2 or more > threads per core. >=20 > By then, other parts of QEMU have already caused the vCPU to run in an > unitialized state a couple of times. For example, ppc_cpu_reset() calls > ppc_tlb_invalidate_all(), which ends up calling async_run_on_cpu(). This > kicks the new vCPU while it has CPUState::halted =3D 0, causing QEMU to i= ssue > a KVM_RUN ioctl on the new vCPU before the guest is able to make the > start-cpu RTAS call to initialize its register state. >=20 > This problem doesn't seem to cause visible issues for regular guests, but > on a secure guest running under the Ultravisor it does. The Ultravisor > relies on being able to snoop on the start-cpu RTAS call to map vCPUs to > guests, and this issue causes it to see a stray vCPU that doesn't belong = to > any guest. >=20 > Fix by setting the start-powered-off CPUState property in > spapr_create_vcpu(), which makes cpu_common_reset() initialize > CPUState::halted to 1 at an earlier moment. >=20 > Suggested-by: Eduardo Habkost > Signed-off-by: Thiago Jung Bauermann Acked-by: David Gibson > --- > hw/ppc/spapr_cpu_core.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) >=20 > NB: Tested on ppc64le pseries KVM guest with two threads per core.=20 > Hot-plugging additional cores doesn't cause the bug described above > anymore. >=20 > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c > index c4f47dcc04..2125fdac34 100644 > --- a/hw/ppc/spapr_cpu_core.c > +++ b/hw/ppc/spapr_cpu_core.c > @@ -36,11 +36,6 @@ static void spapr_reset_vcpu(PowerPCCPU *cpu) > =20 > cpu_reset(cs); > =20 > - /* All CPUs start halted. CPU0 is unhalted from the machine level > - * reset code and the rest are explicitly started up by the guest > - * using an RTAS call */ > - cs->halted =3D 1; > - > env->spr[SPR_HIOR] =3D 0; > =20 > lpcr =3D env->spr[SPR_LPCR]; > @@ -274,6 +269,11 @@ static PowerPCCPU *spapr_create_vcpu(SpaprCpuCore *s= c, int i, Error **errp) > =20 > cs =3D CPU(obj); > cpu =3D POWERPC_CPU(obj); > + /* > + * All CPUs start halted. CPU0 is unhalted from the machine level re= set code > + * and the rest are explicitly started up by the guest using an RTAS= call. > + */ > + cs->start_powered_off =3D true; > cs->cpu_index =3D cc->core_id + i; > spapr_set_vcpu_id(cpu, cs->cpu_index, &local_err); > if (local_err) { >=20 --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --WeDu0lr7bteb/II5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAl8Y/ssACgkQbDjKyiDZ s5KYVxAAv7P27aed2Mohc1UK3Bum8vJaeFcPpfr/EPEfJb78dgyvscEPglAvIBal Ia2ElTiYxzROnRiD209HoBR432VeEELIvXtaO99yp/u0sF2QRBrNtMVcZ3DyUWr2 MbTcD4BSR4Qq1GiCKBGvXtC6fGQv6R1vy3Z31eMqDdPXwnE67DjoiRuuXjQs+DzY J2v5BTMhBWcfMJyirzJq02OReKCSZwhRu15l77j/Wyc7LC9nYM/fZxYHxwKGVEL/ D0w0YpBy7wwtioxKUhuqkeO6ONGc/tWrNTzzDTenfZHUyJ/EC2azYFcSj9y24SiI 2NjUOsTTtvekOlD+4lW2mS2ZonkgIzYiTTa0PLPIZdJZ8P50ZEO3jbuFdmyPc7ur Mz4STuZQT/mPxFuuKU7RPQY04E++cSFIWjYhna3IqTK9K3trICGaC9OhrSQ3EUJp hBepwmoeA+Ik+xte4HR7/r+xRnVWME0hEuR/v4qhMiQ3FuK4j1mNBal9x47LTsUg r39CO8a0b6V/t3NKRT5CShsBDjQPikk2DX4wyMheRL697Tw4N3pkzI40Cpx0QZgP ludgUrzuZ+waEfujZCrPYHac7oRoSrUimV3K54hPoQE4xAAm3rDl97oBpKGHObqk 2AhiTzBtdkoB1ALG9XLNixXU/gExcrfhxYw84SdfbUYd8zdCxBc= =H/Oe -----END PGP SIGNATURE----- --WeDu0lr7bteb/II5--