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Smith" Subject: [PATCH v4 6/8] arm/sysctl: Implement cpu hotplug ops Thread-Topic: [PATCH v4 6/8] arm/sysctl: Implement cpu hotplug ops Thread-Index: AQHcU8JY4MUEJP5v5ECe3RrLj+fwXw== Date: Wed, 12 Nov 2025 10:51:48 +0000 Message-ID: <656cb01061f2ec726eb23784d01517a94117618e.1762939773.git.mykyta_poturai@epam.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=epam.com; x-ms-publictraffictype: Email x-ms-traffictypediagnostic: PAVPR03MB10102:EE_|PAWPR03MB9786:EE_ x-ms-office365-filtering-correlation-id: e2c5d9b2-e834-4c46-91ae-08de21d97b1e x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0;ARA:13230040|1800799024|376014|366016|38070700021; x-microsoft-antispam-message-info: =?iso-8859-1?Q?7WyZVAbBsrJYl/SB/GcPH0Isi8Nlh855KJks4d8wHieoQVkKrIRKUmsdoa?= =?iso-8859-1?Q?QlyqeBjqiS8x99hp26DhueYu0+VvLzqI4P+sJoxXvPtpceaiLT92cN6hy8?= =?iso-8859-1?Q?/Q+DIOHhvlZHupGPaUxBISBFm46+OvG3ITEAoXq/QZ6jH76ow2zt0wBuLL?= =?iso-8859-1?Q?ssBwJ0hOhvwy8hEZC45Ep+jkCXrGA/Yu3Paet4eXMZ37KWjlpjD8r7w1kj?= =?iso-8859-1?Q?Z6lUdMUbarHpOmLyvVI5V3HbB/F56g8hL17QQ5W/0oTm9r39k8r1n3qEuE?= =?iso-8859-1?Q?vEl0Tu2yaIVajzG2Jxg0O8ED0JUJiNhMpCxNTtpvgWcWyTQcoNB5VVEVmH?= =?iso-8859-1?Q?adJUI4wzWxfbai57EvHnK5gCJHOYTEh52pDEwLKEFEYsvjMsGbqVNOkNeq?= =?iso-8859-1?Q?H8rjsu+vs47AeXDe+O/FMQYvT6vK3j9aErRnH/G3mXyqELfm6T9+bOldA1?= =?iso-8859-1?Q?Dm63wBuvdE5GrqylAuMULMgOLdv6p5IiAPEQiYq1YXhjsBsf+M5rAznosM?= =?iso-8859-1?Q?meSGDuhuDMfR5leaJDuTbjSV1rgA2ZWj0OiYIXxAovjBOp+AK9t+nV7AdC?= =?iso-8859-1?Q?S42zdjtX2JYv+qha77pxDy4mQ15ltLERDtQWvZdCSLib2p2aAu9Xq65zhb?= =?iso-8859-1?Q?Xj15iKR6c2unUuQ1fJbjvKBiNZn0vGyeWrETwF27rEx1IHENqa1ldoKVr4?= =?iso-8859-1?Q?HAGSMp5C4Z1W1EVlDNiH/5qEOJ6L7jXK/F/C4neheKPEnkFEeQ3zFhbqrl?= =?iso-8859-1?Q?Ohe2HpY3uh0v1iCeWRObfQx8EFs4557bqfOfA8hbjIhqWT/62IGXl0XhR3?= =?iso-8859-1?Q?kA5WctKCFFJqRJPEvQUU462pC4oXVP7m/17hwPuMyt9nx3RFuQRcsT6poY?= =?iso-8859-1?Q?Rz3HfeVPN/jZ0tGW475VrAyuut/dfMwL9B+MIhFupZ7w7oZa9u0zrS/tZv?= =?iso-8859-1?Q?36CGVKmNgal7yU8hv3raGovGvf2RCmmfPrPzotkjt2r7lJZJpbIWeJXpJP?= =?iso-8859-1?Q?vYtb/I0dAALTd2wLysVOthM6Xck/XfRkBVxJbWXTmQNI76zG2geTdpGFuS?= =?iso-8859-1?Q?YF8hQh6Cuo6rkxMreAncAgemZmLQFttOSAEdrUYfLDgsnC/k5CQAeJf2Ah?= =?iso-8859-1?Q?PimaxqnM1JpPgpv35F455WHvVHtgRU/xE05ET7PREyXS/OCsCXrDPLWlF5?= =?iso-8859-1?Q?zObuP3KqoeakM99KdNDgXJMzFjLw+tQg2QF3tmA6D2w97lhfZgFGVCUg/4?= =?iso-8859-1?Q?VFZP/rQY4ddnczC6rwwM1yIr9Xr9g4LpBNu01IW1hqpH7sRVJX5yXAepV3?= =?iso-8859-1?Q?cfzzhB/Tl5owyf/Cnii8gXLCvAMkzL10TC6veI16v6pMabRnuOmg4VAGbZ?= =?iso-8859-1?Q?ZBOXop+Q6qID5EYrSHS9+yIjcSMN9KQyplUOa8PPWS0f7KCsm5IYKIuWeO?= =?iso-8859-1?Q?eV/y0BfVZ4sekoGHT+saFOFGRAxecojP+kAb4tQL7HObb9iQ46/2+FjzEk?= =?iso-8859-1?Q?3L0fJSBOkvo38R7QF3oHCiDRTn5Zmq6yCwo3kyel7Hu9Q1Z89WwNXAiF8x?= =?iso-8859-1?Q?k7fp13O8aRqycC2XvXGBlooolMQe?= x-forefront-antispam-report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PAVPR03MB10102.eurprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(366016)(38070700021);DIR:OUT;SFP:1101; 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charset="utf-8" Implement XEN_SYSCTL_CPU_HOTPLUG_{ONLINE,OFFLINE} calls to allow for enabling/disabling CPU cores in runtime. For now this operations only support Arm64. For proper Arm32 support, there needs to be a mechanism to free per-cpu page tables, allocated in init_domheap_mappings. Also, hotplug is not supported if ITS, FFA, or TEE is enabled, as they use non-static IRQ actions. Create a Kconfig option RUNTIME_CPU_CONTROL that reflects this constraints. Signed-off-by: Mykyta Poturai v3->v4: * don't reimplement cpu_up/down helpers * add Kconfig option * fixup formatting v2->v3: * no changes v1->v2: * remove SMT ops * remove cpu =3D=3D 0 checks * add XSM hooks * only implement for 64bit Arm --- xen/arch/arm/Kconfig | 4 ++++ xen/arch/arm/sysctl.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+) diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig index cf6af68299..931ae51575 100644 --- a/xen/arch/arm/Kconfig +++ b/xen/arch/arm/Kconfig @@ -274,6 +274,10 @@ config PCI_PASSTHROUGH help This option enables PCI device passthrough =20 +config RUNTIME_CPU_CONTROL + def_bool y + depends on ARM_64 && !TEE && !FFA && !HAS_ITS + endmenu =20 menu "ARM errata workaround via the alternative framework" diff --git a/xen/arch/arm/sysctl.c b/xen/arch/arm/sysctl.c index 32cab4feff..3c4e29d82c 100644 --- a/xen/arch/arm/sysctl.c +++ b/xen/arch/arm/sysctl.c @@ -12,6 +12,7 @@ #include #include #include +#include #include #include =20 @@ -23,6 +24,33 @@ void arch_do_physinfo(struct xen_sysctl_physinfo *pi) XEN_SYSCTL_PHYSCAP_ARM_SVE_MASK); } =20 +static long cpu_hotplug_sysctl(struct xen_sysctl_cpu_hotplug *hotplug) +{ +#ifdef CONFIG_RUNTIME_CPU_CONTROL + int ret; + + switch ( hotplug->op ) + { + case XEN_SYSCTL_CPU_HOTPLUG_ONLINE: + ret =3D xsm_resource_plug_core(XSM_HOOK); + if ( ret ) + return ret; + return continue_hypercall_on_cpu(0, cpu_up_helper, _p(hotplug->cpu= )); + + case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE: + ret =3D xsm_resource_unplug_core(XSM_HOOK); + if ( ret ) + return ret; + return continue_hypercall_on_cpu(0, cpu_down_helper, _p(hotplug->c= pu)); + + default: + return -EOPNOTSUPP; + } +#else + return -EOPNOTSUPP; +#endif +} + long arch_do_sysctl(struct xen_sysctl *sysctl, XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl) { @@ -34,6 +62,10 @@ long arch_do_sysctl(struct xen_sysctl *sysctl, ret =3D dt_overlay_sysctl(&sysctl->u.dt_overlay); break; =20 + case XEN_SYSCTL_cpu_hotplug: + ret =3D cpu_hotplug_sysctl(&sysctl->u.cpu_hotplug); + break; + default: ret =3D -ENOSYS; break; --=20 2.51.2