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Wed, 12 Jul 2023 11:20:27 +0000 (GMT) Message-ID: <234c79fd-1435-71e5-73b7-235724998cdc@linux.ibm.com> Date: Wed, 12 Jul 2023 13:20:26 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v21 02/20] s390x/cpu topology: add topology entries on CPU hotplug Content-Language: en-US To: Thomas Huth , qemu-s390x@nongnu.org Cc: qemu-devel@nongnu.org, borntraeger@de.ibm.com, pasic@linux.ibm.com, richard.henderson@linaro.org, david@redhat.com, cohuck@redhat.com, mst@redhat.com, pbonzini@redhat.com, kvm@vger.kernel.org, ehabkost@redhat.com, marcel.apfelbaum@gmail.com, eblake@redhat.com, armbru@redhat.com, seiden@linux.ibm.com, nrb@linux.ibm.com, nsg@linux.ibm.com, frankja@linux.ibm.com, berrange@redhat.com, clg@kaod.org References: <20230630091752.67190-1-pmorel@linux.ibm.com> <20230630091752.67190-3-pmorel@linux.ibm.com> <71bd9791-cdfe-3930-fdd3-64b27b180c6d@redhat.com> From: Pierre Morel In-Reply-To: <71bd9791-cdfe-3930-fdd3-64b27b180c6d@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: o-G5O88_cSZrRsh6CAoS8AM2HB-voAHv X-Proofpoint-ORIG-GUID: SxJEAFViEbQ-rPP5Mvk1tQKngl1e5GOJ Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-12_06,2023-07-11_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 mlxscore=0 priorityscore=1501 suspectscore=0 adultscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 clxscore=1015 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2305260000 definitions=main-2307120098 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 7/4/23 12:32, Thomas Huth wrote: > On 30/06/2023 11.17, Pierre Morel wrote: >> The topology information are attributes of the CPU and are >> specified during the CPU device creation. >> >> On hot plug we: >> - calculate the default values for the topology for drawers, >>    books and sockets in the case they are not specified. >> - verify the CPU attributes >> - check that we have still room on the desired socket >> >> The possibility to insert a CPU in a mask is dependent on the >> number of cores allowed in a socket, a book or a drawer, the >> checking is done during the hot plug of the CPU to have an >> immediate answer. >> >> If the complete topology is not specified, the core is added >> in the physical topology based on its core ID and it gets >> defaults values for the modifier attributes. >> >> This way, starting QEMU without specifying the topology can >> still get some advantage of the CPU topology. >> >> Signed-off-by: Pierre Morel >> --- > ... >> diff --git a/include/hw/s390x/cpu-topology.h >> b/include/hw/s390x/cpu-topology.h >> new file mode 100644 >> index 0000000000..9164ac00a7 >> --- /dev/null >> +++ b/include/hw/s390x/cpu-topology.h >> @@ -0,0 +1,54 @@ >> +/* SPDX-License-Identifier: GPL-2.0-or-later */ >> +/* >> + * CPU Topology >> + * >> + * Copyright IBM Corp. 2022,2023 > > Nit: Add a space after the comma ? thx > >> + * Author(s): Pierre Morel >> + * >> + */ >> +#ifndef HW_S390X_CPU_TOPOLOGY_H >> +#define HW_S390X_CPU_TOPOLOGY_H >> + >> +#ifndef CONFIG_USER_ONLY >> + >> +#include "qemu/queue.h" >> +#include "hw/boards.h" >> +#include "qapi/qapi-types-machine-target.h" >> + >> +typedef struct S390Topology { >> +    uint8_t *cores_per_socket; >> +} S390Topology; > > So S390Topology has only one entry, "cores_per_socket" here... > > ... >> diff --git a/hw/s390x/cpu-topology.c b/hw/s390x/cpu-topology.c >> new file mode 100644 >> index 0000000000..b163c17f8f >> --- /dev/null >> +++ b/hw/s390x/cpu-topology.c >> @@ -0,0 +1,264 @@ >> +/* SPDX-License-Identifier: GPL-2.0-or-later */ >> +/* >> + * CPU Topology >> + * >> + * Copyright IBM Corp. 2022,2023 >> + * Author(s): Pierre Morel >> + * >> + * S390 topology handling can be divided in two parts: >> + * >> + * - The first part in this file is taking care of all common functions >> + *   used by KVM and TCG to create and modify the topology. >> + * >> + * - The second part, building the topology information data for the >> + *   guest with CPU and KVM specificity will be implemented inside >> + *   the target/s390/kvm sub tree. >> + */ >> + >> +#include "qemu/osdep.h" >> +#include "qapi/error.h" >> +#include "qemu/error-report.h" >> +#include "hw/qdev-properties.h" >> +#include "hw/boards.h" >> +#include "target/s390x/cpu.h" >> +#include "hw/s390x/s390-virtio-ccw.h" >> +#include "hw/s390x/cpu-topology.h" >> + >> +/* >> + * s390_topology is used to keep the topology information. >> + * .cores_per_socket: tracks information on the count of cores >> + *                    per socket. >> + * .smp: keeps track of the machine topology. >> + * > > ... but the description talks about ".smp" here, too, which never > seems to be added. Leftover from a previous iteration? > (also: please remove the empty line at the end of the comment) right, thx > >> + */ >> +S390Topology s390_topology = { >> +    /* will be initialized after the cpu model is realized */ >> +    .cores_per_socket = NULL, >> +}; >> + >> +/** >> + * s390_socket_nb: >> + * @cpu: s390x CPU >> + * >> + * Returns the socket number used inside the cores_per_socket array >> + * for a topology tree entry >> + */ >> +static int __s390_socket_nb(int drawer_id, int book_id, int socket_id) > > Please don't use function names starting with double underscores. This > namespace is reserved by the C standard. > Maybe "s390_socket_nb_from_ids" ? OK > >> +{ >> +    return (drawer_id * current_machine->smp.books + book_id) * >> +           current_machine->smp.sockets + socket_id; >> +} >> + >> +/** >> + * s390_socket_nb: >> + * @cpu: s390x CPU >> + * >> + * Returns the socket number used inside the cores_per_socket array >> + * for a cpu. >> + */ >> +static int s390_socket_nb(S390CPU *cpu) >> +{ >> +    return __s390_socket_nb(cpu->env.drawer_id, cpu->env.book_id, >> +                            cpu->env.socket_id); >> +} >> + >> +/** >> + * s390_has_topology: >> + * >> + * Return value: if the topology is supported by the machine. > > "Return: true if the topology is supported by the machine" > > (QEMU uses kerneldoc style, so it's just "Return:" and not "Return > value:", see e.g. > https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html ) OK, thx > >> + */ >> +bool s390_has_topology(void) >> +{ >> +    return false; >> +} >> + >> +/** >> + * s390_topology_init: >> + * @ms: the machine state where the machine topology is defined >> + * >> + * Keep track of the machine topology. >> + * >> + * Allocate an array to keep the count of cores per socket. >> + * The index of the array starts at socket 0 from book 0 and >> + * drawer 0 up to the maximum allowed by the machine topology. >> + */ >> +static void s390_topology_init(MachineState *ms) >> +{ >> +    CpuTopology *smp = &ms->smp; >> + >> +    s390_topology.cores_per_socket = g_new0(uint8_t, smp->sockets * >> +                                            smp->books * smp->drawers); >> +} >> + >> +/** >> + * s390_topology_cpu_default: >> + * @cpu: pointer to a S390CPU >> + * @errp: Error pointer >> + * >> + * Setup the default topology if no attributes are already set. >> + * Passing a CPU with some, but not all, attributes set is considered >> + * an error. >> + * >> + * The function calculates the (drawer_id, book_id, socket_id) >> + * topology by filling the cores starting from the first socket >> + * (0, 0, 0) up to the last (smp->drawers, smp->books, smp->sockets). >> + * >> + * CPU type and dedication have defaults values set in the >> + * s390x_cpu_properties, entitlement must be adjust depending on the >> + * dedication. >> + * >> + * Returns false if it is impossible to setup a default topology >> + * true otherwise. >> + */ >> +static bool s390_topology_cpu_default(S390CPU *cpu, Error **errp) >> +{ >> +    CpuTopology *smp = ¤t_machine->smp; >> +    CPUS390XState *env = &cpu->env; >> + >> +    /* All geometry topology attributes must be set or all unset */ >> +    if ((env->socket_id < 0 || env->book_id < 0 || env->drawer_id < >> 0) && >> +        (env->socket_id >= 0 || env->book_id >= 0 || env->drawer_id >> >= 0)) { >> +        error_setg(errp, >> +                   "Please define all or none of the topology >> geometry attributes"); >> +        return false; >> +    } >> + >> +    /* Check if one of the geometry topology is unset */ >> +    if (env->socket_id < 0) { >> +        /* Calculate default geometry topology attributes */ >> +        env->socket_id = s390_std_socket(env->core_id, smp); >> +        env->book_id = s390_std_book(env->core_id, smp); >> +        env->drawer_id = s390_std_drawer(env->core_id, smp); >> +    } >> + >> +    /* >> +     * When the user specifies the entitlement as 'auto' on the >> command line, >> +     * qemu will set the entitlement as: > > s/qemu/QEMU/ ok > >> +     * Medium when the CPU is not dedicated. >> +     * High when dedicated is true. >> +     */ >> +    if (env->entitlement == S390_CPU_ENTITLEMENT_AUTO) { >> +        if (env->dedicated) { >> +            env->entitlement = S390_CPU_ENTITLEMENT_HIGH; >> +        } else { >> +            env->entitlement = S390_CPU_ENTITLEMENT_MEDIUM; >> +        } >> +    } >> +    return true; >> +} >> + >> +/** >> + * s390_topology_check: >> + * @socket_id: socket to check >> + * @book_id: book to check >> + * @drawer_id: drawer to check >> + * @entitlement: entitlement to check >> + * @dedicated: dedication to check >> + * @errp: Error pointer >> + * >> + * The function checks if the topology >> + * attributes fits inside the system topology. >> + * >> + * Returns false if the specified topology does not match with >> + * the machine topology. >> + */ >> +static bool s390_topology_check(uint16_t socket_id, uint16_t book_id, >> +                                uint16_t drawer_id, uint16_t >> entitlement, >> +                                bool dedicated, Error **errp) >> +{ >> +    CpuTopology *smp = ¤t_machine->smp; >> +    ERRP_GUARD(); >> + >> +    if (socket_id >= smp->sockets) { >> +        error_setg(errp, "Unavailable socket: %d", socket_id); >> +        return false; >> +    } >> +    if (book_id >= smp->books) { >> +        error_setg(errp, "Unavailable book: %d", book_id); >> +        return false; >> +    } >> +    if (drawer_id >= smp->drawers) { >> +        error_setg(errp, "Unavailable drawer: %d", drawer_id); >> +        return false; >> +    } >> +    if (entitlement >= S390_CPU_ENTITLEMENT__MAX) { >> +        error_setg(errp, "Unknown entitlement: %d", entitlement); >> +        return false; >> +    } >> +    if (dedicated && (entitlement == S390_CPU_ENTITLEMENT_LOW || >> +                      entitlement == S390_CPU_ENTITLEMENT_MEDIUM)) { >> +        error_setg(errp, "A dedicated cpu implies high entitlement"); > > s/cpu/CPU/ ? yes OK > >> +        return false; >> +    } >> +    return true; >> +} >> + >> +/** >> + * s390_update_cpu_props: >> + * @ms: the machine state >> + * @cpu: the CPU for which to update the properties from the >> environment. >> + * >> + */ >> +static void s390_update_cpu_props(MachineState *ms, S390CPU *cpu) >> +{ >> +    CpuInstanceProperties *props; >> + >> +    props = &ms->possible_cpus->cpus[cpu->env.core_id].props; >> + >> +    props->socket_id = cpu->env.socket_id; >> +    props->book_id = cpu->env.book_id; >> +    props->drawer_id = cpu->env.drawer_id; >> +} >> + >> +/** >> + * s390_topology_setup_cpu: >> + * @ms: MachineState used to initialize the topology structure on >> + *      first call. >> + * @cpu: the new S390CPU to insert in the topology structure >> + * @errp: the error pointer >> + * >> + * Called from CPU hotplug to check and setup the CPU attributes >> + * before the CPU is inserted in the topology. >> + * There is no need to update the MTCR explicitly here because it >> + * will be updated by KVM on creation of the new CPU. >> + */ >> +void s390_topology_setup_cpu(MachineState *ms, S390CPU *cpu, Error >> **errp) >> +{ >> +    ERRP_GUARD(); >> +    int entry; >> + >> +    /* >> +     * We do not want to initialize the topology if the cpu model > > s/cpu/CPU/ ok > >> +     * does not support topology, consequently, we have to wait for >> +     * the first CPU to be realized, which realizes the CPU model >> +     * to initialize the topology structures. >> +     * >> +     * s390_topology_setup_cpu() is called from the cpu hotplug. >> +     */ >> +    if (!s390_topology.cores_per_socket) { >> +        s390_topology_init(ms); >> +    } >> + >> +    if (!s390_topology_cpu_default(cpu, errp)) { >> +        return; >> +    } >> + >> +    if (!s390_topology_check(cpu->env.socket_id, cpu->env.book_id, >> +                             cpu->env.drawer_id, cpu->env.entitlement, >> +                             cpu->env.dedicated, errp)) { >> +        return; >> +    } >> + >> +    /* Do we still have space in the socket */ >> +    entry = s390_socket_nb(cpu); >> +    if (s390_topology.cores_per_socket[entry] >= >> current_machine->smp.cores) { >> +        error_setg(errp, "No more space on this socket"); >> +        return; >> +    } >> + >> +    /* Update the count of cores in sockets */ >> +    s390_topology.cores_per_socket[entry] += 1; >> + >> +    /* topology tree is reflected in props */ >> +    s390_update_cpu_props(ms, cpu); >> +} > >  Thomas > > Thanks, I make the changes. Regards, Pierre