Re: [PATCH v2 12/17] arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line

at the cpufeature, but only at the HW registers.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/include/asm/cpufeature.h |  3 +++
 arch/arm64/kernel/cpufeature.c      |  6 +++++-
 arch/arm64/kernel/idreg-override.c  | 12 ++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 465d2cb63bfc..ef9487dfadca 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h

@@ -813,6 +813,9 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
        return 8;
 }

+extern u64 id_aa64mmfr1_val;
+extern u64 id_aa64mmfr1_mask;
+
 u32 get_kvm_ipa_limit(void);
 void dump_cpu_features(void);

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 2dbfc0096b0d..623a74090c9e 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c

@@ -555,6 +555,9 @@ static const struct arm64_ftr_bits ftr_raz[] = {

 #define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, NULL, NULL)

+u64 id_aa64mmfr1_val;
+u64 id_aa64mmfr1_mask;
+
 static const struct __ftr_reg_entry {
        u32                     sys_id;
        struct arm64_ftr_reg    *reg;

@@ -602,7 +605,8 @@ static const struct __ftr_reg_entry {

        /* Op1 = 0, CRn = 0, CRm = 7 */
        ARM64_FTR_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0),
-       ARM64_FTR_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1),
+       ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1,
+                              &id_aa64mmfr1_val, &id_aa64mmfr1_mask),
        ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),

        /* Op1 = 0, CRn = 1, CRm = 2 */

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index 392f93b67103..75d9845f489b 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c

@@ -10,6 +10,7 @@
 #include <linux/libfdt.h>

 #include <asm/cacheflush.h>
+#include <asm/cpufeature.h>
 #include <asm/setup.h>

 struct reg_desc {

@@ -22,7 +23,18 @@ struct reg_desc {
        }                       fields[];
 };

+static const struct reg_desc mmfr1 __initdata = {
+       .name           = "id_aa64mmfr1",
+       .val            = &id_aa64mmfr1_val,
+       .mask           = &id_aa64mmfr1_mask,
+       .fields         = {
+               { "vh", ID_AA64MMFR1_VHE_SHIFT },
+               {}
+       },
+};
+
 static const struct reg_desc * const regs[] __initdata = {
+       &mmfr1,
 };

 static int __init find_field(const char *cmdline, const struct reg_desc *reg,
--

2.29.2

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