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Thu, 22 Aug 2019 20:07:12 +0000 (UTC) Received: from [10.36.116.91] (ovpn-116-91.ams2.redhat.com [10.36.116.91]) by smtp.corp.redhat.com (Postfix) with ESMTP id D3A5E60CDA; Thu, 22 Aug 2019 20:07:10 +0000 (UTC) To: David Gibson , peter.maydell@linaro.org References: <20190813065920.23203-1-david@gibson.dropbear.id.au> <20190813065920.23203-2-david@gibson.dropbear.id.au> From: Laurent Vivier Openpgp: preference=signencrypt 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 7ze5Ag0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5TGxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT 460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwvF8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BN efdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2NyHfmZlPGE0Nsy7hlebS4liisXOrN3jFz asKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqXGcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0 VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eophoWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFM C3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHKXWo+xf9WgtLeby3cfSkEchACrxDrQpj+ Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunTco1+cKSuRiSCYpBIXZMHCzPgVDjk4viP brV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCqkCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6 z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCmdNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JP jfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHBCzkM4rWyRhuVABEBAAGJAh8EGAECAAkF AlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtI WlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b6WimV64FmlVn17Ri6FgFU3xNt9TTEChq AcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2x OhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76J21YeRrEW4WDznPyVcDTa+tz++q2S/Bp P4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjXEYRWdiCxN7ca5iPml5gLtuvhJMSy36gl U6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2TxL8enfx40PrfbDtWwqRID3WY8jLrjKfTd R3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPM oDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyx FCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbLXiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsB kmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZD+Ofp0T3KOr1RUHvCZoLURfFhSQ= Message-ID: Date: Thu, 22 Aug 2019 22:07:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190813065920.23203-2-david@gibson.dropbear.id.au> Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Thu, 22 Aug 2019 20:07:12 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-ppc] [PULL 1/2] spapr: Reset CAS & IRQ subsystem after devices 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: groug@kaod.org, qemu-ppc@nongnu.org, clg@kaod.org, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 13/08/2019 08:59, David Gibson wrote: > This fixes a nasty regression in qemu-4.1 for the 'pseries' machine, > caused by the new "dual" interrupt controller model. Specifically, > qemu can crash when used with KVM if a 'system_reset' is requested > while there's active I/O in the guest. >=20 > The problem is that in spapr_machine_reset() we: >=20 > 1. Reset the CAS vector state > spapr_ovec_cleanup(spapr->ov5_cas); >=20 > 2. Reset all devices > qemu_devices_reset() >=20 > 3. Reset the irq subsystem > spapr_irq_reset(); >=20 > However (1) implicitly changes the interrupt delivery mode, because > whether we're using XICS or XIVE depends on the CAS state. We don't > properly initialize the new irq mode until (3) though - in particular > setting up the KVM devices. >=20 > During (2), we can temporarily drop the BQL allowing some irqs to be > delivered which will go to an irq system that's not properly set up. >=20 > Specifically, if the previous guest was in (KVM) XIVE mode, the CAS > reset will put us back in XICS mode. kvm_kernel_irqchip() still > returns true, because XIVE was using KVM, however XICs doesn't have > its KVM components intialized and kernel_xics_fd =3D=3D -1. When the i= rq > is delivered it goes via ics_kvm_set_irq() which assert()s that > kernel_xics_fd !=3D -1. >=20 > This change addresses the problem by delaying the CAS reset until > after the devices reset. The device reset should quiesce all the > devices so we won't get irqs delivered while we mess around with the > IRQ. The CAS reset and irq re-initialize should also now be under the > same BQL critical section so nothing else should be able to interrupt > it either. >=20 > We also move the spapr_irq_msi_reset() used in one of the legacy irq > modes, since it logically makes sense at the same point as the > spapr_irq_reset() (it's essentially an equivalent operation for older > machine types). Since we don't need to switch between different > interrupt controllers for those old machine types it shouldn't > actually be broken in those cases though. >=20 > Cc: C=C3=A9dric Le Goater >=20 > Fixes: b2e22477 "spapr: add a 'reset' method to the sPAPR IRQ backend" > Fixes: 13db0cd9 "spapr: introduce a new sPAPR IRQ backend supporting > XIVE and XICS" > Signed-off-by: David Gibson > --- > hw/ppc/spapr.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) >=20 > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index 821f0d4a49..12ed4b065c 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -1726,6 +1726,18 @@ static void spapr_machine_reset(MachineState *ma= chine) > spapr_setup_hpt_and_vrma(spapr); > } > =20 > + /* > + * NVLink2-connected GPU RAM needs to be placed on a separate NUMA= node. > + * We assign a new numa ID per GPU in spapr_pci_collect_nvgpu() wh= ich is > + * called from vPHB reset handler so we initialize the counter her= e. > + * If no NUMA is configured from the QEMU side, we start from 1 as= GPU RAM > + * must be equally distant from any other node. > + * The final value of spapr->gpu_numa_id is going to be written to > + * max-associativity-domains in spapr_build_fdt(). > + */ > + spapr->gpu_numa_id =3D MAX(1, nb_numa_nodes); > + qemu_devices_reset(); > + > /* > * If this reset wasn't generated by CAS, we should reset our > * negotiated options and start from scratch > @@ -1741,18 +1753,6 @@ static void spapr_machine_reset(MachineState *ma= chine) > spapr_irq_msi_reset(spapr); > } > =20 > - /* > - * NVLink2-connected GPU RAM needs to be placed on a separate NUMA= node. > - * We assign a new numa ID per GPU in spapr_pci_collect_nvgpu() wh= ich is > - * called from vPHB reset handler so we initialize the counter her= e. > - * If no NUMA is configured from the QEMU side, we start from 1 as= GPU RAM > - * must be equally distant from any other node. > - * The final value of spapr->gpu_numa_id is going to be written to > - * max-associativity-domains in spapr_build_fdt(). > - */ > - spapr->gpu_numa_id =3D MAX(1, nb_numa_nodes); > - qemu_devices_reset(); > - > /* > * This is fixing some of the default configuration of the XIVE > * devices. To be called after the reset of the machine devices. >=20 This commit breaks migration between POWER8 <-> POWER9 hosts: qemu-system-ppc64: error while loading state for instance 0x1 of device '= cpu' qemu-system-ppc64: load of migration failed: Operation not permitted Using a guest with a running 4.18 kernel (RHEL 8) and "-M pseries,max-cpu= -compat=3Dpower8" on both sides. There is no problem if both hosts are of the same kind ( P8 <-> P8 or P9 = <-> P9). Thanks, Laurent