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[RFC PATCH 1/4] sysctl: Introduce XEN_SYSCTL_get_cpu_status_map

From: Teddy Astie <teddy.astie@xxxxxxxxxx>

Date: Wed, 7 Oct 2026 17:46:03 +0200

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Cc: Teddy Astie <teddy.astie@xxxxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Julien Grall <julien@xxxxxxx>, Roger Pau Monné <roger@xxxxxxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>

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List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Introduce XEN_SYSCTL_get_cpu_status_map as a way to get bitmaps of cpu_online_map, cpu_present_map and cpu_possible_map (if available). Signed-off-by: Teddy Astie <teddy.astie@xxxxxxxxxx> --- On x86, cpu_possible_map doesn't exist, that may not be expected. Should we add additional infos like cpu_sibling_mask and cpu_core_mask ? tools/include/xenctrl.h | 4 ++++ tools/libs/ctrl/xc_misc.c | 45 +++++++++++++++++++++++++++++++++++++ xen/common/sysctl.c | 34 ++++++++++++++++++++++++++++ xen/include/public/sysctl.h | 13 +++++++++++ xen/xsm/flask/hooks.c | 1 + 5 files changed, 97 insertions(+) diff --git a/tools/include/xenctrl.h b/tools/include/xenctrl.h index 9f00d4a19d..55804f2f1c 100644 --- a/tools/include/xenctrl.h +++ b/tools/include/xenctrl.h @@ -1145,6 +1145,10 @@ typedef uint32_t xc_node_to_node_dist_t; int xc_physinfo(xc_interface *xch, xc_physinfo_t *info); int xc_cputopoinfo(xc_interface *xch, unsigned *max_cpus, xc_cputopo_t *cputopo); +int xc_get_cpu_status_map(xc_interface *xch, unsigned nr_cpus, + xc_cpumap_t cpu_online_map, + xc_cpumap_t cpu_present_map, + xc_cpumap_t cpu_possible_map); int xc_microcode_update(xc_interface *xch, const void *buf, size_t len, unsigned int flags); int xc_get_cpu_version(xc_interface *xch, struct xenpf_pcpu_version *cpu_ver); diff --git a/tools/libs/ctrl/xc_misc.c b/tools/libs/ctrl/xc_misc.c index 10ddf85667..bff4f5ff01 100644 --- a/tools/libs/ctrl/xc_misc.c +++ b/tools/libs/ctrl/xc_misc.c @@ -264,6 +264,51 @@ int xc_get_ucode_revision(xc_interface *xch, return 0; } +int xc_get_cpu_status_map(xc_interface *xch, unsigned nr_cpus, + xc_cpumap_t cpu_online_map, + xc_cpumap_t cpu_present_map, + xc_cpumap_t cpu_possible_map) +{ + int ret; + struct xen_sysctl sysctl = {}; + struct xen_sysctl_cpu_status_map cpu_status_map; + DECLARE_HYPERCALL_BOUNCE(cpu_online_map, (nr_cpus + 7) / 8, + XC_HYPERCALL_BUFFER_BOUNCE_OUT); + DECLARE_HYPERCALL_BOUNCE(cpu_present_map, (nr_cpus + 7) / 8, + XC_HYPERCALL_BUFFER_BOUNCE_OUT); + DECLARE_HYPERCALL_BOUNCE(cpu_possible_map, (nr_cpus + 7) / 8, + XC_HYPERCALL_BUFFER_BOUNCE_OUT); + + if ( (ret = xc_hypercall_bounce_pre(xch, cpu_online_map)) ) + goto out; + + if ( (ret = xc_hypercall_bounce_pre(xch, cpu_present_map)) ) + goto out; + + if ( (ret = xc_hypercall_bounce_pre(xch, cpu_possible_map)) ) + goto out; + + sysctl.cmd = XEN_SYSCTL_get_cpu_status_map; + + set_xen_guest_handle(cpu_status_map.cpu_online_map.bitmap, cpu_online_map); + cpu_status_map.cpu_online_map.nr_bits = nr_cpus; + set_xen_guest_handle(cpu_status_map.cpu_present_map.bitmap, cpu_present_map); + cpu_status_map.cpu_present_map.nr_bits = nr_cpus; + set_xen_guest_handle(cpu_status_map.cpu_possible_map.bitmap, cpu_possible_map); + cpu_status_map.cpu_possible_map.nr_bits = nr_cpus; + + sysctl.u.cpu_status_map = cpu_status_map; + + ret = do_sysctl(xch, &sysctl); + +out: + xc_hypercall_bounce_post(xch, cpu_online_map); + xc_hypercall_bounce_post(xch, cpu_present_map); + xc_hypercall_bounce_post(xch, cpu_possible_map); + + return ret; +} + int xc_cputopoinfo(xc_interface *xch, unsigned *max_cpus, xc_cputopo_t *cputopo) { diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c index 8fb5ff0af3..840b2243bf 100644 --- a/xen/common/sysctl.c +++ b/xen/common/sysctl.c @@ -474,6 +474,40 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl) if ( ret != -ENOSYS && ret != -EOPNOTSUPP ) copyback = 1; break; + + case XEN_SYSCTL_get_cpu_status_map: + { + struct xen_sysctl_cpu_status_map *csm = &op->u.cpu_status_map; + + if ( !guest_handle_is_null(csm->cpu_online_map.bitmap) ) + { + ret = cpumask_to_xenctl_bitmap(&csm->cpu_online_map, + &cpu_online_map); + if ( ret ) + break; + } + + if ( !guest_handle_is_null(csm->cpu_present_map.bitmap) ) + { + ret = cpumask_to_xenctl_bitmap(&csm->cpu_present_map, + &cpu_present_map); + if ( ret ) + break; + } + + if ( !guest_handle_is_null(csm->cpu_possible_map.bitmap) ) + { +#ifdef CONFIG_X86 + /* On x86, cpu_possible_map doesn't exist, use cpumask_all instead. */ + ret = cpumask_to_xenctl_bitmap(&csm->cpu_possible_map, + &cpumask_all); +#else + ret = cpumask_to_xenctl_bitmap(&csm->cpu_possible_map, + &cpu_possible_map); +#endif + } + break; + } default: ret = arch_do_sysctl(op, u_sysctl); diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h index 63d0ee062b..3a2a1d2402 100644 --- a/xen/include/public/sysctl.h +++ b/xen/include/public/sysctl.h @@ -1181,6 +1181,17 @@ struct xen_sysctl_livepatch_op { } u; }; +/* + * XEN_SYSCTL_get_cpu_status_map + * + * Get bitmaps of CPU status (possible, online, present). + */ +struct xen_sysctl_cpu_status_map { + struct xenctl_bitmap cpu_online_map; + struct xenctl_bitmap cpu_present_map; + struct xenctl_bitmap cpu_possible_map; +}; + #if defined(__i386__) || defined(__x86_64__) /* * XEN_SYSCTL_get_cpu_policy (x86 specific) @@ -1262,6 +1273,7 @@ struct xen_sysctl { /* #define XEN_SYSCTL_set_parameter 28 */ #define XEN_SYSCTL_get_cpu_policy 29 #define XEN_SYSCTL_dt_overlay 30 +#define XEN_SYSCTL_get_cpu_status_map 31 uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */ union { struct xen_sysctl_readconsole readconsole; @@ -1288,6 +1300,7 @@ struct xen_sysctl { struct xen_sysctl_psr_alloc psr_alloc; struct xen_sysctl_cpu_featureset cpu_featureset; struct xen_sysctl_livepatch_op livepatch; + struct xen_sysctl_cpu_status_map cpu_status_map; #if defined(__i386__) || defined(__x86_64__) struct xen_sysctl_cpu_policy cpu_policy; #endif diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c index d65ba0aeae..4ea0aeb1bb 100644 --- a/xen/xsm/flask/hooks.c +++ b/xen/xsm/flask/hooks.c @@ -952,6 +952,7 @@ static int cf_check flask_sysctl(const struct xen_sysctl *op) case XEN_SYSCTL_numainfo: case XEN_SYSCTL_pcitopoinfo: case XEN_SYSCTL_get_cpu_policy: + case XEN_SYSCTL_get_cpu_status_map: return domain_has_xen(current->domain, XEN__PHYSINFO); case XEN_SYSCTL_getdomaininfolist: -- 2.55.0 -- Teddy Astie | Vates XCP-ng Developer XCP-ng & Xen Orchestra - Vates solutions web: https://vates.tech

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