[PATCH v7 31/38] KVM: arm64: Trap disabled features of ID_AA64ISAR1_EL1

[Reiji Watanabe]

Add feature_config_ctrl for PTRAUTH, which is indicated in
ID_AA64ISAR1_EL1, to program configuration register to trap
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 | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 6a8ed59d8d90..0e3cff91f41d 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -299,6 +299,15 @@ static bool trap_raz_wi(struct kvm_vcpu *vcpu,
 	(cpuid_feature_extract_unsigned_field(val, ID_AA64ISAR2_GPA3_SHIFT) >= \
 	 ID_AA64ISAR2_GPA3_ARCHITECTED)
 
+/*
+ * Return true if ptrauth needs to be trapped.
+ * (i.e. if ptrauth is supported on the host but not exposed to the guest)
+ */
+static bool vcpu_need_trap_ptrauth(struct kvm_vcpu *vcpu)
+{
+	return (system_has_full_ptr_auth() && !vcpu_has_ptrauth(vcpu));
+}
+
 /*
  * Feature information to program configuration register to trap or disable
  * guest's using a feature when the feature is not exposed to the guest.
@@ -394,6 +403,11 @@ static void feature_lor_trap_activate(struct kvm_vcpu *vcpu)
 	feature_trap_activate(vcpu, VCPU_HCR_EL2, HCR_TLOR, 0);
 }
 
+static void feature_ptrauth_trap_activate(struct kvm_vcpu *vcpu)
+{
+	feature_trap_activate(vcpu, VCPU_HCR_EL2, 0, HCR_API | HCR_APK);
+}
+
 /* For ID_AA64PFR0_EL1 */
 static struct feature_config_ctrl ftr_ctrl_ras = {
 	.ftr_reg = SYS_ID_AA64PFR0_EL1,
@@ -462,6 +476,12 @@ static struct feature_config_ctrl ftr_ctrl_lor = {
 	.trap_activate = feature_lor_trap_activate,
 };
 
+/* For SYS_ID_AA64ISAR1_EL1 */
+static struct feature_config_ctrl ftr_ctrl_ptrauth = {
+	.ftr_need_trap = vcpu_need_trap_ptrauth,
+	.trap_activate = feature_ptrauth_trap_activate,
+};
+
 #define __FTR_BITS(ftr_sign, ftr_type, bit_pos, safe) {		\
 	.sign = ftr_sign,					\
 	.type = ftr_type,					\
@@ -4416,6 +4436,10 @@ static struct id_reg_desc id_aa64isar1_el1_desc = {
 		U_FTR_BITS(FTR_EXACT, ID_AA64ISAR1_APA_SHIFT, 0),
 		U_FTR_BITS(FTR_EXACT, ID_AA64ISAR1_API_SHIFT, 0),
 	},
+	.trap_features = &(const struct feature_config_ctrl *[]) {
+		&ftr_ctrl_ptrauth,
+		NULL,
+	},
 };
 
 static struct id_reg_desc id_aa64isar2_el1_desc = {
-- 
2.36.0.rc0.470.gd361397f0d-goog