[PATCH 6.12.y 2/3] x86/mce: Set CR4.MCE last during init

[Sasha Levin <sashal@kernel.org>]

From: Yazen Ghannam <yazen.ghannam@amd.com>

[ Upstream commit cfffcf97997bd35f4a59e035523d1762568bdbad ]

Set the CR4.MCE bit as the last step during init. This brings the MCA
init order closer to what is described in the x86 docs.

x86 docs:
  AMD		Intel
  		MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL
  MCG_CTL
  CR4.MCE	CR4.MCE

Current Linux:
  AMD		Intel
  CR4.MCE	CR4.MCE
  MCG_CTL	MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL

Updated Linux:
  AMD		Intel
  MCG_CTL	MCG_CTL
  MCA_CONFIG	MCG_EXT_CTL
  MCi_CTL	MCi_CTL
  CR4.MCE	CR4.MCE

The new init flow will match Intel's docs, but there will still be a
mismatch for AMD regarding MCG_CTL. However, there is no known issue with this
ordering, so leave it for now.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/20250908-wip-mca-updates-v6-0-eef5d6c74b9c@amd.com
Stable-dep-of: a213dfaa2596 ("x86/mce: Set up the polling timer before CMCI discovery")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/cpu/mce/core.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index ba28988c575cf..c95698dd648ac 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1836,8 +1836,6 @@ static void __mcheck_cpu_init_generic(void)
 	bitmap_fill(all_banks, MAX_NR_BANKS);
 	machine_check_poll(MCP_UC | MCP_QUEUE_LOG | m_fl, &all_banks);
 
-	cr4_set_bits(X86_CR4_MCE);
-
 	rdmsrl(MSR_IA32_MCG_CAP, cap);
 	if (cap & MCG_CTL_P)
 		wrmsr(MSR_IA32_MCG_CTL, 0xffffffff, 0xffffffff);
@@ -2258,6 +2256,7 @@ void mcheck_cpu_init(struct cpuinfo_x86 *c)
 	__mcheck_cpu_init_clear_banks();
 	__mcheck_cpu_check_banks();
 	__mcheck_cpu_setup_timer();
+	cr4_set_bits(X86_CR4_MCE);
 }
 
 /*
@@ -2425,6 +2424,7 @@ static void mce_syscore_resume(void)
 	__mcheck_cpu_init_generic();
 	__mcheck_cpu_init_vendor(raw_cpu_ptr(&cpu_info));
 	__mcheck_cpu_init_clear_banks();
+	cr4_set_bits(X86_CR4_MCE);
 }
 
 static struct syscore_ops mce_syscore_ops = {
@@ -2444,6 +2444,7 @@ static void mce_cpu_restart(void *data)
 	__mcheck_cpu_init_generic();
 	__mcheck_cpu_init_clear_banks();
 	__mcheck_cpu_init_timer();
+	cr4_set_bits(X86_CR4_MCE);
 }
 
 /* Reinit MCEs after user configuration changes */
-- 
2.53.0