From: Marc Zyngier <maz@kernel.org>
Date: Fri, 24 Jan 2025 15:44:32 +0000 (+0000)
Subject: KVM: arm64: Plug FEAT_GCS handling
X-Git-Tag: v6.16-rc1~129^2~2^2~3^2~22
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5329358c222fec1132169ab3de9973aa4cd63aa9;p=thirdparty%2Flinux.git

KVM: arm64: Plug FEAT_GCS handling

We don't seem to be handling the GCS-specific exception class.
Handle it by delivering an UNDEF to the guest, and populate the
relevant trap bits.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index ff75695fb8c96..cc5c2eeebab32 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -298,6 +298,16 @@ static int handle_svc(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int kvm_handle_gcs(struct kvm_vcpu *vcpu)
+{
+	/* We don't expect GCS, so treat it with contempt */
+	if (kvm_has_feat(vcpu->kvm, ID_AA64PFR1_EL1, GCS, IMP))
+		WARN_ON_ONCE(1);
+
+	kvm_inject_undefined(vcpu);
+	return 1;
+}
+
 static int handle_other(struct kvm_vcpu *vcpu)
 {
 	bool is_l2 = vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu);
@@ -380,6 +390,7 @@ static exit_handle_fn arm_exit_handlers[] = {
 	[ESR_ELx_EC_BRK64]	= kvm_handle_guest_debug,
 	[ESR_ELx_EC_FP_ASIMD]	= kvm_handle_fpasimd,
 	[ESR_ELx_EC_PAC]	= kvm_handle_ptrauth,
+	[ESR_ELx_EC_GCS]	= kvm_handle_gcs,
 };
 
 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index ce347ddb6fae0..a9ecca4b2fa74 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -5209,6 +5209,14 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu)
 						HFGITR_EL2_nBRBIALL);
 	}
 
+	if (!kvm_has_feat(kvm, ID_AA64PFR1_EL1, GCS, IMP)) {
+		kvm->arch.fgu[HFGRTR_GROUP] |= (HFGRTR_EL2_nGCS_EL0 |
+						HFGRTR_EL2_nGCS_EL1);
+		kvm->arch.fgu[HFGITR_GROUP] |= (HFGITR_EL2_nGCSPUSHM_EL1 |
+						HFGITR_EL2_nGCSSTR_EL1 |
+						HFGITR_EL2_nGCSEPP);
+	}
+
 	set_bit(KVM_ARCH_FLAG_FGU_INITIALIZED, &kvm->arch.flags);
 out:
 	mutex_unlock(&kvm->arch.config_lock);