arm64: Modify _midr_range() functions to read MIDR/REVIDR internally

These changes lay the groundwork for adding support for guest kernels,
allowing them to leverage target CPU implementations provided by the
VMM.

No functional changes intended.

Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250221140229.12588-2-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: shamiali2008

arch/arm64/include/asm/cputype.h

@@ -231,6 +231,16 @@
 
 #define read_cpuid(reg)			read_sysreg_s(SYS_ ## reg)
 
+/*
+ * The CPU ID never changes at run time, so we might as well tell the
+ * compiler that it's constant.  Use this function to read the CPU ID
+ * rather than directly reading processor_id or read_cpuid() directly.
+ */
+static inline u32 __attribute_const__ read_cpuid_id(void)
+{
+	return read_cpuid(MIDR_EL1);
+}
+
 /*
  * Represent a range of MIDR values for a given CPU model and a
  * range of variant/revision values.
@@ -266,31 +276,21 @@ static inline bool midr_is_cpu_model_range(u32 midr, u32 model, u32 rv_min,
 	return _model == model && rv >= rv_min && rv <= rv_max;
 }
 
-static inline bool is_midr_in_range(u32 midr, struct midr_range const *range)
+static inline bool is_midr_in_range(struct midr_range const *range)
 {
-	return midr_is_cpu_model_range(midr, range->model,
+	return midr_is_cpu_model_range(read_cpuid_id(), range->model,
 				       range->rv_min, range->rv_max);
 }
 
 static inline bool
-is_midr_in_range_list(u32 midr, struct midr_range const *ranges)
+is_midr_in_range_list(struct midr_range const *ranges)
 {
 	while (ranges->model)
-		if (is_midr_in_range(midr, ranges++))
+		if (is_midr_in_range(ranges++))
 			return true;
 	return false;
 }
 
-/*
- * The CPU ID never changes at run time, so we might as well tell the
- * compiler that it's constant.  Use this function to read the CPU ID
- * rather than directly reading processor_id or read_cpuid() directly.
- */
-static inline u32 __attribute_const__ read_cpuid_id(void)
-{
-	return read_cpuid(MIDR_EL1);
-}
-
 static inline u64 __attribute_const__ read_cpuid_mpidr(void)
 {
 	return read_cpuid(MPIDR_EL1);

arch/arm64/include/asm/mmu.h

@@ -101,8 +101,7 @@ static inline bool kaslr_requires_kpti(void)
 	if (IS_ENABLED(CONFIG_CAVIUM_ERRATUM_27456)) {
 		extern const struct midr_range cavium_erratum_27456_cpus[];
 
-		if (is_midr_in_range_list(read_cpuid_id(),
-					  cavium_erratum_27456_cpus))
+		if (is_midr_in_range_list(cavium_erratum_27456_cpus))
 			return false;
 	}
 

arch/arm64/kernel/cpu_errata.c

@@ -15,30 +15,34 @@
 #include <asm/smp_plat.h>
 
 static bool __maybe_unused
-is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
+__is_affected_midr_range(const struct arm64_cpu_capabilities *entry,
+			 u32 midr, u32 revidr)
 {
 	const struct arm64_midr_revidr *fix;
-	u32 midr = read_cpuid_id(), revidr;
-
-	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
-	if (!is_midr_in_range(midr, &entry->midr_range))
+	if (!is_midr_in_range(&entry->midr_range))
 		return false;
 
 	midr &= MIDR_REVISION_MASK | MIDR_VARIANT_MASK;
-	revidr = read_cpuid(REVIDR_EL1);
 	for (fix = entry->fixed_revs; fix && fix->revidr_mask; fix++)
 		if (midr == fix->midr_rv && (revidr & fix->revidr_mask))
 			return false;
-
 	return true;
 }
 
+static bool __maybe_unused
+is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
+{
+	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
+	return __is_affected_midr_range(entry, read_cpuid_id(),
+					read_cpuid(REVIDR_EL1));
+}
+
 static bool __maybe_unused
 is_affected_midr_range_list(const struct arm64_cpu_capabilities *entry,
 			    int scope)
 {
 	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
-	return is_midr_in_range_list(read_cpuid_id(), entry->midr_range_list);
+	return is_midr_in_range_list(entry->midr_range_list);
 }
 
 static bool __maybe_unused
@@ -186,12 +190,11 @@ static bool __maybe_unused
 has_neoverse_n1_erratum_1542419(const struct arm64_cpu_capabilities *entry,
 				int scope)
 {
-	u32 midr = read_cpuid_id();
 	bool has_dic = read_cpuid_cachetype() & BIT(CTR_EL0_DIC_SHIFT);
 	const struct midr_range range = MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N1);
 
 	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
-	return is_midr_in_range(midr, &range) && has_dic;
+	return is_midr_in_range(&range) && has_dic;
 }
 
 #ifdef CONFIG_ARM64_WORKAROUND_REPEAT_TLBI

arch/arm64/kernel/cpufeature.c

@@ -1792,7 +1792,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 	char const *str = "kpti command line option";
 	bool meltdown_safe;
 
-	meltdown_safe = is_midr_in_range_list(read_cpuid_id(), kpti_safe_list);
+	meltdown_safe = is_midr_in_range_list(kpti_safe_list);
 
 	/* Defer to CPU feature registers */
 	if (has_cpuid_feature(entry, scope))
@@ -1862,7 +1862,7 @@ static bool has_nv1(const struct arm64_cpu_capabilities *entry, int scope)
 
 	return (__system_matches_cap(ARM64_HAS_NESTED_VIRT) &&
 		!(has_cpuid_feature(entry, scope) ||
-		  is_midr_in_range_list(read_cpuid_id(), nv1_ni_list)));
+		  is_midr_in_range_list(nv1_ni_list)));
 }
 
 #if defined(ID_AA64MMFR0_EL1_TGRAN_LPA2) && defined(ID_AA64MMFR0_EL1_TGRAN_2_SUPPORTED_LPA2)
@@ -2045,7 +2045,7 @@ static bool cpu_has_broken_dbm(void)
 		{},
 	};
 
-	return is_midr_in_range_list(read_cpuid_id(), cpus);
+	return is_midr_in_range_list(cpus);
 }
 
 static bool cpu_can_use_dbm(const struct arm64_cpu_capabilities *cap)

arch/arm64/kernel/proton-pack.c

@@ -172,7 +172,7 @@ static enum mitigation_state spectre_v2_get_cpu_hw_mitigation_state(void)
 		return SPECTRE_UNAFFECTED;
 
 	/* Alternatively, we have a list of unaffected CPUs */
-	if (is_midr_in_range_list(read_cpuid_id(), spectre_v2_safe_list))
+	if (is_midr_in_range_list(spectre_v2_safe_list))
 		return SPECTRE_UNAFFECTED;
 
 	return SPECTRE_VULNERABLE;
@@ -331,7 +331,7 @@ bool has_spectre_v3a(const struct arm64_cpu_capabilities *entry, int scope)
 	};
 
 	WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
-	return is_midr_in_range_list(read_cpuid_id(), spectre_v3a_unsafe_list);
+	return is_midr_in_range_list(spectre_v3a_unsafe_list);
 }
 
 void spectre_v3a_enable_mitigation(const struct arm64_cpu_capabilities *__unused)
@@ -475,7 +475,7 @@ static enum mitigation_state spectre_v4_get_cpu_hw_mitigation_state(void)
 		{ /* sentinel */ },
 	};
 
-	if (is_midr_in_range_list(read_cpuid_id(), spectre_v4_safe_list))
+	if (is_midr_in_range_list(spectre_v4_safe_list))
 		return SPECTRE_UNAFFECTED;
 
 	/* CPU features are detected first */
@@ -878,13 +878,13 @@ u8 spectre_bhb_loop_affected(int scope)
 			{},
 		};
 
-		if (is_midr_in_range_list(read_cpuid_id(), spectre_bhb_k32_list))
+		if (is_midr_in_range_list(spectre_bhb_k32_list))
 			k = 32;
-		else if (is_midr_in_range_list(read_cpuid_id(), spectre_bhb_k24_list))
+		else if (is_midr_in_range_list(spectre_bhb_k24_list))
 			k = 24;
-		else if (is_midr_in_range_list(read_cpuid_id(), spectre_bhb_k11_list))
+		else if (is_midr_in_range_list(spectre_bhb_k11_list))
 			k = 11;
-		else if (is_midr_in_range_list(read_cpuid_id(), spectre_bhb_k8_list))
+		else if (is_midr_in_range_list(spectre_bhb_k8_list))
 			k =  8;
 
 		max_bhb_k = max(max_bhb_k, k);
@@ -926,8 +926,7 @@ static bool is_spectre_bhb_fw_affected(int scope)
 		MIDR_ALL_VERSIONS(MIDR_CORTEX_A75),
 		{},
 	};
-	bool cpu_in_list = is_midr_in_range_list(read_cpuid_id(),
-					 spectre_bhb_firmware_mitigated_list);
+	bool cpu_in_list = is_midr_in_range_list(spectre_bhb_firmware_mitigated_list);
 
 	if (scope != SCOPE_LOCAL_CPU)
 		return system_affected;

arch/arm64/kvm/vgic/vgic-v3.c

@@ -633,7 +633,7 @@ static const struct midr_range broken_seis[] = {
 static bool vgic_v3_broken_seis(void)
 {
 	return ((kvm_vgic_global_state.ich_vtr_el2 & ICH_VTR_SEIS_MASK) &&
-		is_midr_in_range_list(read_cpuid_id(), broken_seis));
+		is_midr_in_range_list(broken_seis));
 }
 
 /**

drivers/clocksource/arm_arch_timer.c

@@ -842,7 +842,7 @@ static u64 __arch_timer_check_delta(void)
 		{},
 	};
 
-	if (is_midr_in_range_list(read_cpuid_id(), broken_cval_midrs)) {
+	if (is_midr_in_range_list(broken_cval_midrs)) {
 		pr_warn_once("Broken CNTx_CVAL_EL1, using 31 bit TVAL instead.\n");
 		return CLOCKSOURCE_MASK(31);
 	}

drivers/hwtracing/coresight/coresight-etm4x-core.c

@@ -1216,7 +1216,7 @@ static void etm4_fixup_wrong_ccitmin(struct etmv4_drvdata *drvdata)
 	 * recorded value for 'drvdata->ccitmin' to workaround
 	 * this problem.
 	 */
-	if (is_midr_in_range_list(read_cpuid_id(), etm_wrong_ccitmin_cpus)) {
+	if (is_midr_in_range_list(etm_wrong_ccitmin_cpus)) {
 		if (drvdata->ccitmin == 256)
 			drvdata->ccitmin = 4;
 	}