[PATCH v7 14/23] arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line

Marc Zyngier
2021-02-08T10:21:16Z

As we want to be able to disable VHE at runtime, let's match
"id_aa64mmfr1.vh=" from the command line as an override.
This doesn't have much effect yet as our boot code doesn't look
at the cpufeature, but only at the HW registers.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 2 ++
arch/arm64/kernel/cpufeature.c | 5 ++++-
arch/arm64/kernel/idreg-override.c | 11 +++++++++++
3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index b5bf7af68691..570f1b4ba3cc 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -818,6 +818,8 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
return 8;
}

+extern struct arm64_ftr_override id_aa64mmfr1_override;
+
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 97da9ed4b79d..faada5d8bea6 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -557,6 +557,8 @@ static const struct arm64_ftr_bits ftr_raz[] = {

#define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, &no_override)

+struct arm64_ftr_override __ro_after_init id_aa64mmfr1_override;
+
static const struct __ftr_reg_entry {
u32 sys_id;
struct arm64_ftr_reg *reg;
@@ -604,7 +606,8 @@ 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_override),
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 3a347b42d07e..2da11bf60195 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -11,6 +11,7 @@
#include <linux/libfdt.h>

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

#define FTR_DESC_NAME_LEN 20
@@ -25,7 +26,17 @@ struct ftr_set_desc {
} fields[];
};

+static const struct ftr_set_desc mmfr1 __initconst = {
+ .name = "id_aa64mmfr1",
+ .override = &id_aa64mmfr1_override,
+ .fields = {
+ { "vh", ID_AA64MMFR1_VHE_SHIFT },
+ {}
+ },
+};
+
static const struct ftr_set_desc * const regs[] __initconst = {
+ &mmfr1,
};

static int __init find_field(const char *cmdline,
--
2.29.2