[PATCH v2 5/5] x86/smpboot: Remove STARTUP_SECONDARY

From: Brian Gerst
Date: Fri Feb 24 2023 - 10:43:04 EST


All CPUs now use the same setup path. Remove STARTUP_SECONDARY and
renumber the remaining flags.

Signed-off-by: Brian Gerst <brgerst@xxxxxxxxx>
---
arch/x86/include/asm/smp.h | 5 ++---
arch/x86/kernel/head_64.S | 5 ++---
arch/x86/kernel/smpboot.c | 6 +++---
3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index b4b29e052b6e..97a36d029b0e 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -202,8 +202,7 @@ extern unsigned int smpboot_control;
#endif /* !__ASSEMBLY__ */

/* Control bits for startup_64 */
-#define STARTUP_SECONDARY 0x80000000
-#define STARTUP_APICID_CPUID_0B 0x40000000
-#define STARTUP_APICID_CPUID_01 0x20000000
+#define STARTUP_APICID_CPUID_0B 0x80000000
+#define STARTUP_APICID_CPUID_01 0x40000000

#endif /* _ASM_X86_SMP_H */
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 8bd29ab523dd..f629bf74217b 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -240,9 +240,8 @@ SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL)
* used to look up the CPU number. For booting a single CPU, the
* CPU number is encoded in smpboot_control.
*
- * Bit 31 STARTUP_SECONDARY flag (checked above)
- * Bit 30 STARTUP_APICID_CPUID_0B flag (use CPUID 0x0b)
- * Bit 29 STARTUP_APICID_CPUID_01 flag (use CPUID 0x01)
+ * Bit 31 STARTUP_APICID_CPUID_0B flag (use CPUID 0x0b)
+ * Bit 30 STARTUP_APICID_CPUID_01 flag (use CPUID 0x01)
* Bit 0-24 CPU# if STARTUP_APICID_CPUID_xx flags are not set
*/
movl smpboot_control(%rip), %ecx
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index e1a2843c2841..c159a5c2df9f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1140,7 +1140,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(cpu);
initial_stack = idle->thread.sp;
} else if (!do_parallel_bringup) {
- smpboot_control = STARTUP_SECONDARY | cpu;
+ smpboot_control = cpu;
}

/* Enable the espfix hack for this CPU */
@@ -1580,7 +1580,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
*/
if (eax) {
pr_debug("Using CPUID 0xb for parallel CPU startup\n");
- smpboot_control = STARTUP_SECONDARY | STARTUP_APICID_CPUID_0B;
+ smpboot_control = STARTUP_APICID_CPUID_0B;
} else {
pr_info("Disabling parallel bringup because CPUID 0xb looks untrustworthy\n");
do_parallel_bringup = false;
@@ -1588,7 +1588,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
} else if (do_parallel_bringup) {
/* Without X2APIC, what's in CPUID 0x01 should suffice. */
pr_debug("Using CPUID 0x1 for parallel CPU startup\n");
- smpboot_control = STARTUP_SECONDARY | STARTUP_APICID_CPUID_01;
+ smpboot_control = STARTUP_APICID_CPUID_01;
}

if (do_parallel_bringup) {
--
2.39.2