x86/cacheinfo: Switch cache_ap_init() to hotplug callback

Instead of explicitly calling cache_ap_init() in
identify_secondary_cpu() use a CPU hotplug callback instead. By
registering the callback only after having started the non-boot CPUs
and initializing cache_aps_delayed_init with "true", calling
set_cache_aps_delayed_init() at boot time can be dropped.

It should be noted that this change results in cache_ap_init() being
called a little bit later when hotplugging CPUs. By using a new
hotplug slot right at the start of the low level bringup this is not
problematic, as no operations requiring a specific caching mode are
performed that early in CPU initialization.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20221102074713.21493-15-jgross@suse.com
Signed-off-by: Borislav Petkov <bp@suse.de>

diff --git a/arch/x86/include/asm/cacheinfo.h b/arch/x86/include/asm/cacheinfo.h
index a0ef46e9f4533292e42556976cde9c8dec8f6cea..ce9685fc78d8ffc125eaed0aa75f9e65135bfe79 100644 (file)
--- a/arch/x86/include/asm/cacheinfo.h
+++ b/arch/x86/include/asm/cacheinfo.h
@@ -16,7 +16,6 @@ void set_cache_aps_delayed_init(bool val);
 bool get_cache_aps_delayed_init(void);
 void cache_bp_init(void);
 void cache_bp_restore(void);
-void cache_ap_init(void);
 void cache_aps_init(void);
 
 #endif /* _ASM_X86_CACHEINFO_H */

diff --git a/arch/x86/kernel/cpu/cacheinfo.c b/arch/x86/kernel/cpu/cacheinfo.c
index c830f853e3b1053ed48c1c5cc7111a3ef4f82ed5..f4e5aa27eec657a5dc01af4a53cf90e87bc5bbe4 100644 (file)
--- a/arch/x86/kernel/cpu/cacheinfo.c
+++ b/arch/x86/kernel/cpu/cacheinfo.c
@@ -11,6 +11,7 @@
 #include <linux/slab.h>
 #include <linux/cacheinfo.h>
 #include <linux/cpu.h>
+#include <linux/cpuhotplug.h>
 #include <linux/sched.h>
 #include <linux/capability.h>
 #include <linux/sysfs.h>
@@ -1139,7 +1140,7 @@ static void cache_cpu_init(void)
        local_irq_restore(flags);
 }
 
-static bool cache_aps_delayed_init;
+static bool cache_aps_delayed_init = true;
 
 void set_cache_aps_delayed_init(bool val)
 {
@@ -1174,10 +1175,10 @@ void cache_bp_restore(void)
                cache_cpu_init();
 }
 
-void cache_ap_init(void)
+static int cache_ap_init(unsigned int cpu)
 {
        if (!memory_caching_control || get_cache_aps_delayed_init())
-               return;
+               return 0;
 
        /*
         * Ideally we should hold mtrr_mutex here to avoid MTRR entries
@@ -1194,6 +1195,8 @@ void cache_ap_init(void)
         */
        stop_machine_from_inactive_cpu(cache_rendezvous_handler, NULL,
                                       cpu_callout_mask);
+
+       return 0;
 }
 
 /*
@@ -1207,3 +1210,12 @@ void cache_aps_init(void)
        stop_machine(cache_rendezvous_handler, NULL, cpu_online_mask);
        set_cache_aps_delayed_init(false);
 }
+
+static int __init cache_ap_register(void)
+{
+       cpuhp_setup_state_nocalls(CPUHP_AP_CACHECTRL_STARTING,
+                                 "x86/cachectrl:starting",
+                                 cache_ap_init, NULL);
+       return 0;
+}
+core_initcall(cache_ap_register);

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index fd058b547f8d4e3cedfecd3938c773d119f36911..bf4ac1cb93d725a8071542af041a4c58429fca1a 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1949,7 +1949,6 @@ void identify_secondary_cpu(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_32
        enable_sep_cpu();
 #endif
-       cache_ap_init();
        validate_apic_and_package_id(c);
        x86_spec_ctrl_setup_ap();
        update_srbds_msr();

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 1b61a480c966c4e51f2aaa2f024062577888db18..82b311c718bc0c9080e11ccf2c4e22d3a6a05ef9 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1429,8 +1429,6 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
        uv_system_init();
 
-       set_cache_aps_delayed_init(true);
-
        smp_quirk_init_udelay();
 
        speculative_store_bypass_ht_init();

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db97e5461a85b8daec0ef0e6fe4cc93..0d277b4b025a5fd6621d6a32df4d01475a8515bc 100644 (file)
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -140,6 +140,7 @@ enum cpuhp_state {
         */
        CPUHP_AP_IDLE_DEAD,
        CPUHP_AP_OFFLINE,
+       CPUHP_AP_CACHECTRL_STARTING,
        CPUHP_AP_SCHED_STARTING,
        CPUHP_AP_RCUTREE_DYING,
        CPUHP_AP_CPU_PM_STARTING,