From: Qemu-devel [mailto:qemu-devel-bounces+salil.mehta=huawei.com@nongnu.org] On Behalf Of Yanan Wang Sent: Sunday, May 16, 2021 11:32 AM To: Peter Maydell <peter.maydell@linaro.org>; Paolo Bonzini <pbonzini@redhat.com>; Andrew Jones <drjones@redhat.com>; Michael S . Tsirkin <mst@redhat.com>; Igor Mammedov <imammedo@redhat.com>; Shannon Zhao <shannon.zhaosl@gmail.com>; qemu-devel@nongnu.org; qemu-arm@nongnu.org Cc: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>; Philippe Mathieu-Daudé <philmd@redhat.com>; wangyanan (Y) <wangyanan55@huawei.com>; Zengtao (B) <prime.zeng@hisilicon.com>; Wanghaibin (D) <wanghaibin.wang@huawei.com>; yuzenghui <yuzenghui@huawei.com>; yangyicong <yangyicong@huawei.com>; zhukeqian <zhukeqian1@huawei.com> Subject: [RFC PATCH v3 4/4] hw/arm/virt: Parse -smp cluster parameter in virt_smp_parse

There is a separate function virt_smp_parse() in hw/virt/arm.c used to parse cpu topology for the ARM machines. So add parsing of -smp cluster parameter in it, then total number of logical cpus will be calculated like: max_cpus = sockets * clusters * cores * threads.

Note, we will assume multi-cluster in one socket is not supported and default the value of clusters to 1, if it's not explicitly specified in -smp cmdline.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com> --- hw/arm/virt.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c index 7de822e491..678d5ef36c 100644 --- a/hw/arm/virt.c +++ b/hw/arm/virt.c @@ -2642,8 +2642,8 @@ static int virt_kvm_type(MachineState *ms, const char *type_str) * with the -smp cmdlines when parsing them. * * We require that at least one of cpus or maxcpus must be provided. - * Threads will default to 1 if not provided. Sockets and cores must - * be either both provided or both not. + * Clusters and threads will default to 1 if they are not provided. + * Sockets and cores must be either both provided or both not. * * Note, if neither sockets nor cores are specified, we will calculate * all the missing values just like smp_parse() does, but will disable @@ -2652,15 +2652,18 @@ static int virt_kvm_type(MachineState *ms, const char *type_str) static void virt_smp_parse(MachineState *ms, QemuOpts *opts) { VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(ms); + VirtMachineState *vms = VIRT_MACHINE(ms);

if (opts) { unsigned cpus = qemu_opt_get_number(opts, "cpus", 0); unsigned maxcpus = qemu_opt_get_number(opts, "maxcpus", 0); unsigned sockets = qemu_opt_get_number(opts, "sockets", 0); + unsigned clusters = qemu_opt_get_number(opts, "clusters", 0); unsigned cores = qemu_opt_get_number(opts, "cores", 0); unsigned threads = qemu_opt_get_number(opts, "threads", 0);

- /* Default threads to 1 if not provided */ + /* Default clusters and threads to 1 if not provided */ + clusters = clusters > 0 ? clusters : 1; threads = threads > 0 ? threads : 1;

if (cpus == 0 && maxcpus == 0) { @@ -2676,13 +2679,13 @@ static void virt_smp_parse(MachineState *ms, QemuOpts *opts) cores = 1; if (cpus == 0) { sockets = 1; - cpus = sockets * cores * threads; + cpus = sockets * clusters * cores * threads; } else { maxcpus = maxcpus > 0 ? maxcpus : cpus; - sockets = maxcpus / (cores * threads); + sockets = maxcpus / (clusters * cores * threads); } } else if (sockets > 0 && cores > 0) { - cpus = cpus > 0 ? cpus : sockets * cores * threads; + cpus = cpus > 0 ? cpus : sockets * clusters * cores * threads; maxcpus = maxcpus > 0 ? maxcpus : cpus; } else { error_report("sockets and cores must be both provided " @@ -2695,25 +2698,26 @@ static void virt_smp_parse(MachineState *ms, QemuOpts *opts) exit(1); }

- if (sockets * cores * threads < cpus) { + if (sockets * clusters * cores * threads < cpus) { error_report("cpu topology: " - "sockets (%u) * cores (%u) * threads (%u) < " - "smp_cpus (%u)", - sockets, cores, threads, cpus); + "sockets (%u) * clusters (%u) * cores (%u) * " + "threads (%u) < smp_cpus (%u)", + sockets, clusters, cores, threads, cpus); exit(1); }

- if (sockets * cores * threads != maxcpus) { + if (sockets * clusters * cores * threads != maxcpus) { error_report("cpu topology: " - "sockets (%u) * cores (%u) * threads (%u) " - "!= maxcpus (%u)", - sockets, cores, threads, maxcpus); + "sockets (%u) * clusters (%u) * cores (%u) * " + "threads (%u) != maxcpus (%u)", + sockets, clusters, cores, threads, maxcpus); exit(1); }

ms->smp.cpus = cpus; ms->smp.max_cpus = maxcpus; ms->smp.sockets = sockets; + vms->smp_clusters = clusters;

This variable naming *smp_clusters* looks out-of-sorts. I thought a similar variable *smp_cpus* was destined to be removed for the reason given in below link - a patch by Andrew Jones? Link: https://lists.gnu.org/archive/html/qemu-arm/2020-12/msg00418.html Am I missing anything here? Salil.

ms->smp.cores = cores; ms->smp.threads = threads; }