Merge tag 'x86-urgent-2023-10-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Fix a false-positive KASAN warning, fix an AMD erratum on Zen4 CPUs,
  and fix kernel-doc build warnings"

* tag 'x86-urgent-2023-10-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/alternatives: Disable KASAN in apply_alternatives()
  x86/cpu: Fix AMD erratum #1485 on Zen4-based CPUs
  x86/resctrl: Fix kernel-doc warnings

arch/x86/include/asm/msr-index.h

@@ -637,12 +637,17 @@
 /* AMD Last Branch Record MSRs */
 #define MSR_AMD64_LBR_SELECT			0xc000010e
 
-/* Fam 17h MSRs */
-#define MSR_F17H_IRPERF			0xc00000e9
+/* Zen4 */
+#define MSR_ZEN4_BP_CFG			0xc001102e
+#define MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT 5
 
+/* Zen 2 */
 #define MSR_ZEN2_SPECTRAL_CHICKEN	0xc00110e3
 #define MSR_ZEN2_SPECTRAL_CHICKEN_BIT	BIT_ULL(1)
 
+/* Fam 17h MSRs */
+#define MSR_F17H_IRPERF			0xc00000e9
+
 /* Fam 16h MSRs */
 #define MSR_F16H_L2I_PERF_CTL		0xc0010230
 #define MSR_F16H_L2I_PERF_CTR		0xc0010231

arch/x86/kernel/alternative.c

@@ -403,6 +403,17 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
 	u8 insn_buff[MAX_PATCH_LEN];
 
 	DPRINTK(ALT, "alt table %px, -> %px", start, end);
+
+	/*
+	 * In the case CONFIG_X86_5LEVEL=y, KASAN_SHADOW_START is defined using
+	 * cpu_feature_enabled(X86_FEATURE_LA57) and is therefore patched here.
+	 * During the process, KASAN becomes confused seeing partial LA57
+	 * conversion and triggers a false-positive out-of-bound report.
+	 *
+	 * Disable KASAN until the patching is complete.
+	 */
+	kasan_disable_current();
+
 	/*
 	 * The scan order should be from start to end. A later scanned
 	 * alternative code can overwrite previously scanned alternative code.
@@ -452,6 +463,8 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
 
 		text_poke_early(instr, insn_buff, insn_buff_sz);
 	}
+
+	kasan_enable_current();
 }
 
 static inline bool is_jcc32(struct insn *insn)

arch/x86/kernel/cpu/amd.c

@@ -80,6 +80,10 @@ static const int amd_div0[] =
 	AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x17, 0x00, 0x0, 0x2f, 0xf),
 			   AMD_MODEL_RANGE(0x17, 0x50, 0x0, 0x5f, 0xf));
 
+static const int amd_erratum_1485[] =
+	AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x19, 0x10, 0x0, 0x1f, 0xf),
+			   AMD_MODEL_RANGE(0x19, 0x60, 0x0, 0xaf, 0xf));
+
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)
 {
 	int osvw_id = *erratum++;
@@ -1149,6 +1153,10 @@ static void init_amd(struct cpuinfo_x86 *c)
 		pr_notice_once("AMD Zen1 DIV0 bug detected. Disable SMT for full protection.\n");
 		setup_force_cpu_bug(X86_BUG_DIV0);
 	}
+
+	if (!cpu_has(c, X86_FEATURE_HYPERVISOR) &&
+	     cpu_has_amd_erratum(c, amd_erratum_1485))
+		msr_set_bit(MSR_ZEN4_BP_CFG, MSR_ZEN4_BP_CFG_SHARED_BTB_FIX_BIT);
 }
 
 #ifdef CONFIG_X86_32

arch/x86/kernel/cpu/resctrl/monitor.c

@@ -30,15 +30,15 @@ struct rmid_entry {
 	struct list_head		list;
 };
 
-/**
- * @rmid_free_lru    A least recently used list of free RMIDs
+/*
+ * @rmid_free_lru - A least recently used list of free RMIDs
  *     These RMIDs are guaranteed to have an occupancy less than the
  *     threshold occupancy
  */
 static LIST_HEAD(rmid_free_lru);
 
-/**
- * @rmid_limbo_count     count of currently unused but (potentially)
+/*
+ * @rmid_limbo_count - count of currently unused but (potentially)
  *     dirty RMIDs.
  *     This counts RMIDs that no one is currently using but that
  *     may have a occupancy value > resctrl_rmid_realloc_threshold. User can
@@ -46,7 +46,7 @@ static LIST_HEAD(rmid_free_lru);
  */
 static unsigned int rmid_limbo_count;
 
-/**
+/*
  * @rmid_entry - The entry in the limbo and free lists.
  */
 static struct rmid_entry	*rmid_ptrs;