[RFC PATCH 08/25] KVM: arm64: Make ID_AA64ISAR0_EL1 writable

[Reiji Watanabe]

This patch adds id_reg_info for ID_AA64ISAR0_EL1 to make it writable
by userspace.

Updating sm3, sm4, sha1, sha2 and sha3 fields are allowed only
if values of those fields follow Arm ARM.

Signed-off-by: Reiji Watanabe <reijiw at google.com>
---
 arch/arm64/kvm/sys_regs.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 0e4423a81cb9..73b5dad0b2ee 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -328,6 +328,31 @@ static int validate_id_aa64pfr1_el1(struct kvm_vcpu *vcpu, u64 val)
 	return 0;
 }
 
+static int validate_id_aa64isar0_el1(struct kvm_vcpu *vcpu, u64 val)
+{
+	unsigned int sm3, sm4, sha1, sha2, sha3;
+
+	/* Run consistency checkings according to Arm ARM */
+	sm3 = cpuid_feature_extract_unsigned_field(val, ID_AA64ISAR0_SM3_SHIFT);
+	sm4 = cpuid_feature_extract_unsigned_field(val, ID_AA64ISAR0_SM4_SHIFT);
+	if (sm3 != sm4)
+		return -EINVAL;
+
+	sha1 = cpuid_feature_extract_unsigned_field(val,
+						    ID_AA64ISAR0_SHA1_SHIFT);
+	sha2 = cpuid_feature_extract_unsigned_field(val,
+						    ID_AA64ISAR0_SHA2_SHIFT);
+	if ((sha1 == 0) ^ (sha2 == 0))
+		return -EINVAL;
+
+	sha3 = cpuid_feature_extract_unsigned_field(val,
+						    ID_AA64ISAR0_SHA3_SHIFT);
+	if (((sha2 == 2) ^ (sha3 == 1)) || (!sha1 && sha3))
+		return -EINVAL;
+
+	return 0;
+}
+
 static void init_id_aa64pfr0_el1_info(struct id_reg_info *id_reg)
 {
 	u64 limit;
@@ -396,6 +421,11 @@ static struct id_reg_info id_aa64pfr1_el1_info = {
 	.get_reset_val = get_reset_id_aa64pfr1_el1,
 };
 
+static struct id_reg_info id_aa64isar0_el1_info = {
+	.sys_reg = SYS_ID_AA64ISAR0_EL1,
+	.validate = validate_id_aa64isar0_el1,
+};
+
 /*
  * An ID register that needs special handling to control the value for the
  * guest must have its own id_reg_info in id_reg_info_table.
@@ -407,6 +437,7 @@ static struct id_reg_info id_aa64pfr1_el1_info = {
 static struct id_reg_info *id_reg_info_table[KVM_ARM_ID_REG_MAX_NUM] = {
 	[IDREG_IDX(SYS_ID_AA64PFR0_EL1)] = &id_aa64pfr0_el1_info,
 	[IDREG_IDX(SYS_ID_AA64PFR1_EL1)] = &id_aa64pfr1_el1_info,
+	[IDREG_IDX(SYS_ID_AA64ISAR0_EL1)] = &id_aa64isar0_el1_info,
 };
 
 static int validate_id_reg(struct kvm_vcpu *vcpu,
-- 
2.33.0.882.g93a45727a2-goog