linux-kernel - [PATCH v2 5/5] x86/smpboot: Remove STARTUP

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Date:   Fri, 24 Feb 2023 10:42:35 -0500
From:   Brian Gerst <brgerst@...il.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Usama Arif <usama.arif@...edance.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Brian Gerst <brgerst@...il.com>
Subject: [PATCH v2 5/5] x86/smpboot: Remove STARTUP_SECONDARY

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

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 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