[RFC PATCH v4 21/26] KVM: arm64: Trap disabled features of ID_AA64PFR1_EL1

[Reiji Watanabe]

Add feature_config_ctrl for MTE, which is indicated in
ID_AA64PFR1_EL1, to program configuration register to trap the
guest's using the feature when it is not exposed to the guest.

Signed-off-by: Reiji Watanabe <reijiw at google.com>
---
 arch/arm64/kvm/sys_regs.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 015d67092d5e..72e745c5a9c2 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -344,6 +344,11 @@ static void feature_amu_trap_activate(struct kvm_vcpu *vcpu)
 	feature_trap_activate(vcpu, VCPU_CPTR_EL2, CPTR_EL2_TAM, 0);
 }
 
+static void feature_mte_trap_activate(struct kvm_vcpu *vcpu)
+{
+	feature_trap_activate(vcpu, VCPU_HCR_EL2, HCR_TID5, HCR_DCT | HCR_ATA);
+}
+
 /* For ID_AA64PFR0_EL1 */
 static struct feature_config_ctrl ftr_ctrl_ras = {
 	.ftr_reg = SYS_ID_AA64PFR0_EL1,
@@ -361,6 +366,15 @@ static struct feature_config_ctrl ftr_ctrl_amu = {
 	.trap_activate = feature_amu_trap_activate,
 };
 
+/* For ID_AA64PFR1_EL1 */
+static struct feature_config_ctrl ftr_ctrl_mte = {
+	.ftr_reg = SYS_ID_AA64PFR1_EL1,
+	.ftr_shift = ID_AA64PFR1_MTE_SHIFT,
+	.ftr_min = ID_AA64PFR1_MTE_EL0,
+	.ftr_signed = FTR_UNSIGNED,
+	.trap_activate = feature_mte_trap_activate,
+};
+
 struct id_reg_info {
 	u32	sys_reg;	/* Register ID */
 	u64	sys_val;	/* Sanitized system value */
@@ -847,6 +861,10 @@ static struct id_reg_info id_aa64pfr1_el1_info = {
 	.init = init_id_aa64pfr1_el1_info,
 	.validate = validate_id_aa64pfr1_el1,
 	.vcpu_mask = vcpu_mask_id_aa64pfr1_el1,
+	.trap_features = &(const struct feature_config_ctrl *[]) {
+		&ftr_ctrl_mte,
+		NULL,
+	},
 };
 
 static struct id_reg_info id_aa64isar0_el1_info = {
-- 
2.34.1.448.ga2b2bfdf31-goog