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Wed, 20 Nov 2019 11:28:22 +0000 (UTC) Received: from [10.36.116.216] (ovpn-116-216.ams2.redhat.com [10.36.116.216]) by smtp.corp.redhat.com (Postfix) with ESMTP id DEED7600C9; Wed, 20 Nov 2019 11:28:19 +0000 (UTC) Subject: Re: [PATCH] spapr: Fix VSMT mode when it is not supported by the kernel From: Laurent Vivier To: David Gibson , Greg Kurz References: <20191108154035.12913-1-lvivier@redhat.com> <20191108174759.2d4040f1@bahia.lan> <20191119010012.GI5582@umbus.fritz.box> <20191119164526.0e980a37@bahia.lan> <20191120043653.GG5582@umbus.fritz.box> Autocrypt: addr=lvivier@redhat.com; prefer-encrypt=mutual; keydata= mQINBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABtCNMYXVyZW50IFZp dmllciA8bHZpdmllckByZWRoYXQuY29tPokCOAQTAQIAIgUCVgVQgAIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjwpgg//fSGy0Rs/t8cPFuzoY1cex4limJQfReLr SJXCANg9NOWy/bFK5wunj+h/RCFxIFhZcyXveurkBwYikDPUrBoBRoOJY/BHK0iZo7/WQkur 6H5losVZtrotmKOGnP/lJYZ3H6OWvXzdz8LL5hb3TvGOP68K8Bn8UsIaZJoeiKhaNR0sOJyI YYbgFQPWMHfVwHD/U+/gqRhD7apVysxv5by/pKDln1I5v0cRRH6hd8M8oXgKhF2+rAOL7gvh jEHSSWKUlMjC7YwwjSZmUkL+TQyE18e2XBk85X8Da3FznrLiHZFHQ/NzETYxRjnOzD7/kOVy gKD/o7asyWQVU65mh/ECrtjfhtCBSYmIIVkopoLaVJ/kEbVJQegT2P6NgERC/31kmTF69vn8 uQyW11Hk8tyubicByL3/XVBrq4jZdJW3cePNJbTNaT0d/bjMg5zCWHbMErUib2Nellnbg6bc 2HLDe0NLVPuRZhHUHM9hO/JNnHfvgiRQDh6loNOUnm9Iw2YiVgZNnT4soUehMZ7au8PwSl4I KYE4ulJ8RRiydN7fES3IZWmOPlyskp1QMQBD/w16o+lEtY6HSFEzsK3o0vuBRBVp2WKnssVH qeeV01ZHw0bvWKjxVNOksP98eJfWLfV9l9e7s6TaAeySKRRubtJ+21PRuYAxKsaueBfUE7ZT 7ze0LUxhdXJlbnQgVml2aWVyIChSZWQgSGF0KSA8bHZpdmllckByZWRoYXQuY29tPokCOAQT AQIAIgUCVgUmGQIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjxtNBAA o2xGmbXl9vJQALkj7MVlsMlgewQ1rdoZl+bZ6ythTSBsqwwtl1BUTQGA1GF2LAchRVYca5bJ lw4ai5OdZ/rc5dco2XgrRFtj1np703BzNEhGU1EFxtms/Y9YOobq/GZpck5rK8jV4osEb8oc 3xEgCm/xFwI/2DOe0/s2cHKzRkvdmKWEDhT1M+7UhtSCnloX776zCsrofYiHP2kasFyMa/5R 9J1Rt9Ax/jEAX5vFJ8+NPf68497nBfrAtLM3Xp03YJSr/LDxer44Mevhz8dFw7IMRLhnuSfr 8jP93lr6Wa8zOe3pGmFXZWpNdkV/L0HaeKwTyDKKdUDH4U7SBnE1gcDfe9x08G+oDfVhqED8 qStKCxPYxRUKIdUjGPF3f5oj7N56Q5zZaZkfxeLNTQ13LDt3wGbVHyZxzFc81B+qT8mkm74y RbeVSuviPTYjbBQ66GsUgiZZpDUyJ6s54fWqQdJf4VFwd7M/mS8WEejbSjglGHMxMGiBeRik Y0+ur5KAF7z0D1KfW1kHO9ImQ0FbEbMbTMf9u2+QOCrSWOz/rj23EwPrCQ2TSRI2fWakMJZ+ zQZvy+ei3D7lZ09I9BT/GfFkTIONgtNfDxwyMc4v4XyP0IvvZs/YZqt7j3atyTZM0S2HSaZ9 rXmQYkBt1/u691cZfvy+Tr2xZaDpFcjPkci5Ag0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5T Gxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwv F8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BNefdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2N yHfmZlPGE0Nsy7hlebS4liisXOrN3jFzasKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqX Gcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eoph oWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFMC3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHK XWo+xf9WgtLeby3cfSkEchACrxDrQpj+Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunT co1+cKSuRiSCYpBIXZMHCzPgVDjk4viPbrV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCq kCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCm dNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JPjfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHB CzkM4rWyRhuVABEBAAGJAh8EGAECAAkFAlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3 TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtIWlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b 6WimV64FmlVn17Ri6FgFU3xNt9TTEChqAcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+ klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2xOhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76 J21YeRrEW4WDznPyVcDTa+tz++q2S/BpP4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjX EYRWdiCxN7ca5iPml5gLtuvhJMSy36glU6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2Tx L8enfx40PrfbDtWwqRID3WY8jLrjKfTdR3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/ jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPMoDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1 pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyxFCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbL XiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsBkmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZ D+Ofp0T3KOr1RUHvCZoLURfFhSQ= Message-ID: <0c1f57ac-0823-4268-429b-d1aee8f7f8d5@redhat.com> Date: Wed, 20 Nov 2019 12:28:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: Fkw1T6VIPBOX6-q52qhM-w-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: =?UTF-8?B?THVrw6HFoSBEb2t0b3I=?= , Juan Quintela , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , qemu-ppc@nongnu.org, clg@kaod.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 20/11/2019 10:00, Laurent Vivier wrote: > On 20/11/2019 05:36, David Gibson wrote: >> On Tue, Nov 19, 2019 at 04:45:26PM +0100, Greg Kurz wrote: >>> On Tue, 19 Nov 2019 15:06:51 +0100 >>> Laurent Vivier wrote: >>> >>>> On 19/11/2019 02:00, David Gibson wrote: >>>>> On Fri, Nov 08, 2019 at 05:47:59PM +0100, Greg Kurz wrote: >>>>>> On Fri, 8 Nov 2019 16:40:35 +0100 >>>>>> Laurent Vivier wrote: >>>>>> >>>>>>> Commit 29cb4187497d sets by default the VSMT to smp_threads, >>>>>>> but older kernels (< 4.13) don't support that. >>>>>>> >>>>>>> We can reasonably restore previous behavior with this kernel >>>>>>> to allow to run QEMU as before. >>>>>>> >>>>>>> If VSMT is not supported, VSMT will be set to MAX(8, smp_threads) >>>>>>> as it is done for previous machine types (< pseries-4.2) >>>>>>> >>>>>> >>>>>> It is usually _bad_ to base the machine behavior on host capabilitie= s. >>>>>> What happens if we migrate between an older kernel and a recent one = ? >>>>> >>>>> Right. We're really trying to remove instaces of such behaviour. I'= d >>>>> prefer to completely revert Greg's original patch than to re-introduc= e >>>>> host configuration dependency into the guest configuration.. >>>>> >>>>>> I understand this is to fix tests/migration-test on older kernels. >>>>>> Couldn't this be achieved with migration-test doing some introspecti= on >>>>>> and maybe pass vsmt=3D8 on the QEMU command line ? >>>>> >>>>> ..adjusting the test case like this might be a better idea, though. >>>>> >>>>> What's the test setup where we're using the old kernel? I really onl= y >>>>> applied the original patch on the guess that we didn't really care >>>>> about kernels that old. The fact you've hit this in practice makes m= e >>>>> doubt that assumption. >>>>> >>>> >>>> The way to fix the tests is to add "-smp threads=3D8" on the command l= ine >>>> (for all tests, so basically in qtest_init_without_qmp_handshake(), an= d >>>> it will impact all the machine types), and we have to check if it is >>> >>> Ohhh... it isn't possible to initialize Qtest with machine specific >>> properties ? That's a bit unfortunate :-\ >> >> Uhh... I don't see why we can't. Couldn't we just put either -machine >> vsmt=3D8 or -smp 8 into the cmd_src / cmd_dst printfs() in the >> strcmp(arch, "ppc64") case? >=20 > Yes, but we need to do that to all other tests that fail. test-migration > is not the only one impacted by the problem (we have also pxe-test), so > it's why I thought to fix the problem in a generic place. >=20 > But it seems there are only this couple of tests that are impacted so I > can modify both instead. I think only tests that really start CPU have > the problem. >=20 > I'm going to send a patch to fix that. And again, it's a little bit more complicated than expected: setting vsmt to 8 works only with kvm_hv, but breaks in case of TCG or kvm_pr. So the test must check what is in use... Thanks, Laurent