[PATCH v3 2/4] x86/bus_lock: Add support for AMD

[Ravi Bangoria]

Add Bus Lock Detect (called Bus Lock Trap in AMD docs) support for AMD
platforms. Bus Lock Detect is enumerated with CPUID Fn0000_0007_ECX_x0
bit [24 / BUSLOCKTRAP]. It can be enabled through MSR_IA32_DEBUGCTLMSR.
When enabled, hardware clears DR6[11] and raises a #DB exception on
occurrence of Bus Lock if CPL > 0. More detail about the feature can be
found in AMD APM[1].

[1]: AMD64 Architecture Programmer's Manual Pub. 40332, Rev. 4.07 - June
     2023, Vol 2, 13.1.3.6 Bus Lock Trap
     https://bugzilla.kernel.org/attachment.cgi?id=304653

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
---
 arch/x86/include/asm/cpu.h     | 8 +++++---
 arch/x86/kernel/cpu/bus_lock.c | 4 ++--
 arch/x86/kernel/cpu/common.c   | 2 ++
 arch/x86/kernel/cpu/intel.c    | 1 -
 include/linux/sched.h          | 2 +-
 5 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
index 051d872d2faf..c17fdf899835 100644
--- a/arch/x86/include/asm/cpu.h
+++ b/arch/x86/include/asm/cpu.h
@@ -26,14 +26,13 @@ int mwait_usable(const struct cpuinfo_x86 *);
 unsigned int x86_family(unsigned int sig);
 unsigned int x86_model(unsigned int sig);
 unsigned int x86_stepping(unsigned int sig);
-#ifdef CONFIG_CPU_SUP_INTEL
+#if defined(CONFIG_CPU_SUP_INTEL) || defined(CONFIG_CPU_SUP_AMD)
 extern void __init sld_setup(struct cpuinfo_x86 *c);
 extern bool handle_user_split_lock(struct pt_regs *regs, long error_code);
 extern bool handle_guest_split_lock(unsigned long ip);
 extern void handle_bus_lock(struct pt_regs *regs);
 void split_lock_init(void);
 void bus_lock_init(void);
-u8 get_this_hybrid_cpu_type(void);
 #else
 static inline void __init sld_setup(struct cpuinfo_x86 *c) {}
 static inline bool handle_user_split_lock(struct pt_regs *regs, long error_code)
@@ -49,7 +48,10 @@ static inline bool handle_guest_split_lock(unsigned long ip)
 static inline void handle_bus_lock(struct pt_regs *regs) {}
 static inline void split_lock_init(void) {}
 static inline void bus_lock_init(void) {}
-
+#endif
+#ifdef CONFIG_CPU_SUP_INTEL
+u8 get_this_hybrid_cpu_type(void);
+#else
 static inline u8 get_this_hybrid_cpu_type(void)
 {
 	return 0;
diff --git a/arch/x86/kernel/cpu/bus_lock.c b/arch/x86/kernel/cpu/bus_lock.c
index cffb3f2838dc..74c3ae6f1cd2 100644
--- a/arch/x86/kernel/cpu/bus_lock.c
+++ b/arch/x86/kernel/cpu/bus_lock.c
@@ -11,7 +11,7 @@
 #include <asm/traps.h>
 #include <asm/cpu.h>
 
-#if defined(CONFIG_CPU_SUP_INTEL)
+#if defined(CONFIG_CPU_SUP_INTEL) || defined(CONFIG_CPU_SUP_AMD)
 
 enum split_lock_detect_state {
 	sld_off = 0,
@@ -407,4 +407,4 @@ void __init sld_setup(struct cpuinfo_x86 *c)
 	sld_state_show();
 }
 
-#endif /* defined(CONFIG_CPU_SUP_INTEL) */
+#endif /* defined(CONFIG_CPU_SUP_INTEL) || defined(CONFIG_CPU_SUP_AMD) */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index d4e539d4e158..a37670e1ab4d 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1832,6 +1832,8 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	if (this_cpu->c_init)
 		this_cpu->c_init(c);
 
+	bus_lock_init();
+
 	/* Disable the PN if appropriate */
 	squash_the_stupid_serial_number(c);
 
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 8a483f4ad026..799f18545c6e 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -610,7 +610,6 @@ static void init_intel(struct cpuinfo_x86 *c)
 	init_intel_misc_features(c);
 
 	split_lock_init();
-	bus_lock_init();
 
 	intel_init_thermal(c);
 }
diff --git a/include/linux/sched.h b/include/linux/sched.h
index d4cc144f72a3..6d1ff27e2f55 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -991,7 +991,7 @@ struct task_struct {
 #ifdef CONFIG_ARCH_HAS_CPU_PASID
 	unsigned			pasid_activated:1;
 #endif
-#ifdef	CONFIG_CPU_SUP_INTEL
+#if defined(CONFIG_CPU_SUP_INTEL) || defined(CONFIG_CPU_SUP_AMD)
 	unsigned			reported_split_lock:1;
 #endif
 #ifdef CONFIG_TASK_DELAY_ACCT
-- 
2.34.1