linux-kernel - [PATCH v3 40/44] x86/amd_nb: Trickle down 'struct cpuinfo

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Message-ID: <20250612234010.572636-41-darwi@linutronix.de>
Date: Fri, 13 Jun 2025 01:40:06 +0200
From: "Ahmed S. Darwish" <darwi@...utronix.de>
To: Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	Ard Biesheuvel <ardb@...nel.org>,
	John Ogness <john.ogness@...utronix.de>,
	x86@...nel.org,
	x86-cpuid@...ts.linux.dev,
	LKML <linux-kernel@...r.kernel.org>,
	"Ahmed S. Darwish" <darwi@...utronix.de>
Subject: [PATCH v3 40/44] x86/amd_nb: Trickle down 'struct cpuinfo_x86' reference

Prepare cpuid_amd_hygon_has_l3_cache(), which is internally a
CPUID(0x80000006) call site, for using the parsed CPUID API instead of
invoking direct CPUID queries.

Since such an API requires a 'struct cpuinfo_x86' reference, trickle it
down from the start of the amd_nb initcall.

Note, accessing the CPUID tables at initcall_5 using this_cpu_ptr()
should be safe, since the 'struct cpuinfo_x86' per-CPU presentation is
finalized at arch/x86/kernel/cpu/common.c :: arch_cpu_finalize_init().
Meanwhile, at kernel init/main.c, do_initcalls() are done much later.

Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
---
 arch/x86/kernel/amd_nb.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index c1acead6227a..a8809778b208 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -16,6 +16,7 @@
 
 #include <asm/amd/nb.h>
 #include <asm/cpuid/api.h>
+#include <asm/processor.h>
 
 static u32 *flush_words;
 
@@ -58,7 +59,7 @@ struct amd_northbridge *node_to_amd_nb(int node)
 }
 EXPORT_SYMBOL_GPL(node_to_amd_nb);
 
-static int amd_cache_northbridges(void)
+static int amd_cache_northbridges(struct cpuinfo_x86 *c)
 {
 	struct amd_northbridge *nb;
 	u16 i;
@@ -315,11 +316,13 @@ static __init void fix_erratum_688(void)
 
 static __init int init_amd_nbs(void)
 {
+	struct cpuinfo_x86 *c = this_cpu_ptr(&cpu_info);
+
 	if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
 	    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
 		return 0;
 
-	amd_cache_northbridges();
+	amd_cache_northbridges(c);
 	amd_cache_gart();
 
 	fix_erratum_688();
-- 
2.49.0