[PATCH v7 08/38] KVM: arm64: Make ID_AA64ISAR0_EL1 writable

[Reiji Watanabe <reijiw@xxxxxxxxxx>]

This patch adds id_reg_desc 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@xxxxxxxxxx>
---
 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 c3537cd4fe58..c01038cbdb31 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -425,6 +425,29 @@ static int validate_id_aa64pfr1_el1(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
+static int validate_id_aa64isar0_el1(struct kvm_vcpu *vcpu,
+				     const struct id_reg_desc *id_reg, 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_desc(struct id_reg_desc *id_reg)
 {
 	u64 limit = id_reg->vcpu_limit_val;
@@ -3256,6 +3279,11 @@ static struct id_reg_desc id_aa64pfr1_el1_desc = {
 	.vcpu_mask = vcpu_mask_id_aa64pfr1_el1,
 };
 
+static struct id_reg_desc id_aa64isar0_el1_desc = {
+	.reg_desc = ID_SANITISED(ID_AA64ISAR0_EL1),
+	.validate = validate_id_aa64isar0_el1,
+};
+
 #define ID_DESC(id_reg_name, id_reg_desc)	\
 	[IDREG_IDX(SYS_##id_reg_name)] = (id_reg_desc)
 
@@ -3264,6 +3292,9 @@ static struct id_reg_desc *id_reg_desc_table[KVM_ARM_ID_REG_MAX_NUM] = {
 	/* CRm=4 */
 	ID_DESC(ID_AA64PFR0_EL1, &id_aa64pfr0_el1_desc),
 	ID_DESC(ID_AA64PFR1_EL1, &id_aa64pfr1_el1_desc),
+
+	/* CRm=6 */
+	ID_DESC(ID_AA64ISAR0_EL1, &id_aa64isar0_el1_desc),
 };
 
 static inline struct id_reg_desc *get_id_reg_desc(u32 id)
-- 
2.36.0.rc0.470.gd361397f0d-goog