[PATCH v2 09/13] arm64: Add override for ID_AA64MMFR4_EL1.E2H0

[Marc Zyngier]

Allow ID_AA64MMFR4_EL1.E2H0 to be overriden from the command-line.
This will subsequently be of use for non-compliant CPUs.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/cpufeature.h |  1 +
 arch/arm64/kernel/cpufeature.c      |  4 +++-
 arch/arm64/kernel/idreg-override.c  | 10 ++++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 5f3f62efebd5..d465db251939 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -901,6 +901,7 @@ s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new, s64 cur);
 struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id);
 
 extern struct arm64_ftr_override id_aa64mmfr1_override;
+extern struct arm64_ftr_override id_aa64mmfr4_override;
 extern struct arm64_ftr_override id_aa64pfr0_override;
 extern struct arm64_ftr_override id_aa64pfr1_override;
 extern struct arm64_ftr_override id_aa64zfr0_override;
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 64a026cc5cec..7dcda39537f8 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -691,6 +691,7 @@ static const struct arm64_ftr_bits ftr_raz[] = {
 	__ARM64_FTR_REG_OVERRIDE(#id, id, table, &no_override)
 
 struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
+struct arm64_ftr_override __ro_after_init id_aa64mmfr4_override;
 struct arm64_ftr_override __ro_after_init id_aa64pfr0_override;
 struct arm64_ftr_override __ro_after_init id_aa64pfr1_override;
 struct arm64_ftr_override __ro_after_init id_aa64zfr0_override;
@@ -759,7 +760,8 @@ static const struct __ftr_reg_entry {
 			       &id_aa64mmfr1_override),
 	ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),
 	ARM64_FTR_REG(SYS_ID_AA64MMFR3_EL1, ftr_id_aa64mmfr3),
-	ARM64_FTR_REG(SYS_ID_AA64MMFR4_EL1, ftr_id_aa64mmfr4),
+	ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64MMFR4_EL1, ftr_id_aa64mmfr4,
+			       &id_aa64mmfr4_override),
 
 	/* Op1 = 1, CRn = 0, CRm = 0 */
 	ARM64_FTR_REG(SYS_GMID_EL1, ftr_gmid),
diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 3addc09f8746..7b5b9dc20e6b 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -55,6 +55,15 @@ static const struct ftr_set_desc mmfr1 __initconst = {
 	},
 };
 
+static const struct ftr_set_desc mmfr4 __initconst = {
+	.name		= "id_aa64mmfr4",
+	.override	= &id_aa64mmfr4_override,
+	.fields		= {
+		FIELD("e2h0", ID_AA64MMFR4_EL1_E2H0_SHIFT, NULL ),
+		{}
+	},
+};
+
 static bool __init pfr0_sve_filter(u64 val)
 {
 	/*
@@ -161,6 +170,7 @@ static const struct ftr_set_desc sw_features __initconst = {
 
 static const struct ftr_set_desc * const regs[] __initconst = {
 	&mmfr1,
+	&mmfr4,
 	&pfr0,
 	&pfr1,
 	&isar1,
-- 
2.39.2