1 files changed, 138 insertions, 9 deletions

diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 76dfda116e56..2ad57b117385 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -65,6 +65,136 @@ static inline void __activate_traps_fpsimd32(struct kvm_vcpu *vcpu)
 	}
 }
 
+static inline void __activate_cptr_traps_nvhe(struct kvm_vcpu *vcpu)
+{
+	u64 val = CPTR_NVHE_EL2_RES1 | CPTR_EL2_TAM | CPTR_EL2_TTA;
+
+	/*
+	 * Always trap SME since it's not supported in KVM.
+	 * TSM is RES1 if SME isn't implemented.
+	 */
+	val |= CPTR_EL2_TSM;
+
+	if (!vcpu_has_sve(vcpu) || !guest_owns_fp_regs())
+		val |= CPTR_EL2_TZ;
+
+	if (!guest_owns_fp_regs())
+		val |= CPTR_EL2_TFP;
+
+	write_sysreg(val, cptr_el2);
+}
+
+static inline void __activate_cptr_traps_vhe(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * With VHE (HCR.E2H == 1), accesses to CPACR_EL1 are routed to
+	 * CPTR_EL2. In general, CPACR_EL1 has the same layout as CPTR_EL2,
+	 * except for some missing controls, such as TAM.
+	 * In this case, CPTR_EL2.TAM has the same position with or without
+	 * VHE (HCR.E2H == 1) which allows us to use here the CPTR_EL2.TAM
+	 * shift value for trapping the AMU accesses.
+	 */
+	u64 val = CPTR_EL2_TAM | CPACR_EL1_TTA;
+	u64 cptr;
+
+	if (guest_owns_fp_regs()) {
+		val |= CPACR_EL1_FPEN;
+		if (vcpu_has_sve(vcpu))
+			val |= CPACR_EL1_ZEN;
+	}
+
+	if (!vcpu_has_nv(vcpu))
+		goto write;
+
+	/*
+	 * The architecture is a bit crap (what a surprise): an EL2 guest
+	 * writing to CPTR_EL2 via CPACR_EL1 can't set any of TCPAC or TTA,
+	 * as they are RES0 in the guest's view. To work around it, trap the
+	 * sucker using the very same bit it can't set...
+	 */
+	if (vcpu_el2_e2h_is_set(vcpu) && is_hyp_ctxt(vcpu))
+		val |= CPTR_EL2_TCPAC;
+
+	/*
+	 * Layer the guest hypervisor's trap configuration on top of our own if
+	 * we're in a nested context.
+	 */
+	if (is_hyp_ctxt(vcpu))
+		goto write;
+
+	cptr = vcpu_sanitised_cptr_el2(vcpu);
+
+	/*
+	 * Pay attention, there's some interesting detail here.
+	 *
+	 * The CPTR_EL2.xEN fields are 2 bits wide, although there are only two
+	 * meaningful trap states when HCR_EL2.TGE = 0 (running a nested guest):
+	 *
+	 *  - CPTR_EL2.xEN = x0, traps are enabled
+	 *  - CPTR_EL2.xEN = x1, traps are disabled
+	 *
+	 * In other words, bit[0] determines if guest accesses trap or not. In
+	 * the interest of simplicity, clear the entire field if the guest
+	 * hypervisor has traps enabled to dispel any illusion of something more
+	 * complicated taking place.
+	 */
+	if (!(SYS_FIELD_GET(CPACR_EL1, FPEN, cptr) & BIT(0)))
+		val &= ~CPACR_EL1_FPEN;
+	if (!(SYS_FIELD_GET(CPACR_EL1, ZEN, cptr) & BIT(0)))
+		val &= ~CPACR_EL1_ZEN;
+
+	if (kvm_has_feat(vcpu->kvm, ID_AA64MMFR3_EL1, S2POE, IMP))
+		val |= cptr & CPACR_EL1_E0POE;
+
+	val |= cptr & CPTR_EL2_TCPAC;
+
+write:
+	write_sysreg(val, cpacr_el1);
+}
+
+static inline void __activate_cptr_traps(struct kvm_vcpu *vcpu)
+{
+	if (!guest_owns_fp_regs())
+		__activate_traps_fpsimd32(vcpu);
+
+	if (has_vhe() || has_hvhe())
+		__activate_cptr_traps_vhe(vcpu);
+	else
+		__activate_cptr_traps_nvhe(vcpu);
+}
+
+static inline void __deactivate_cptr_traps_nvhe(struct kvm_vcpu *vcpu)
+{
+	u64 val = CPTR_NVHE_EL2_RES1;
+
+	if (!cpus_have_final_cap(ARM64_SVE))
+		val |= CPTR_EL2_TZ;
+	if (!cpus_have_final_cap(ARM64_SME))
+		val |= CPTR_EL2_TSM;
+
+	write_sysreg(val, cptr_el2);
+}
+
+static inline void __deactivate_cptr_traps_vhe(struct kvm_vcpu *vcpu)
+{
+	u64 val = CPACR_EL1_FPEN;
+
+	if (cpus_have_final_cap(ARM64_SVE))
+		val |= CPACR_EL1_ZEN;
+	if (cpus_have_final_cap(ARM64_SME))
+		val |= CPACR_EL1_SMEN;
+
+	write_sysreg(val, cpacr_el1);
+}
+
+static inline void __deactivate_cptr_traps(struct kvm_vcpu *vcpu)
+{
+	if (has_vhe() || has_hvhe())
+		__deactivate_cptr_traps_vhe(vcpu);
+	else
+		__deactivate_cptr_traps_nvhe(vcpu);
+}
+
 #define reg_to_fgt_masks(reg)						\
 	({								\
 		struct fgt_masks *m;					\
@@ -486,11 +616,6 @@ static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu)
 	 */
 	if (system_supports_sve()) {
 		__hyp_sve_save_host();
-
-		/* Re-enable SVE traps if not supported for the guest vcpu. */
-		if (!vcpu_has_sve(vcpu))
-			cpacr_clear_set(CPACR_EL1_ZEN, 0);
-
 	} else {
 		__fpsimd_save_state(host_data_ptr(host_ctxt.fp_regs));
 	}
@@ -541,10 +666,7 @@ static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
 	/* Valid trap.  Switch the context: */
 
 	/* First disable enough traps to allow us to update the registers */
-	if (sve_guest || (is_protected_kvm_enabled() && system_supports_sve()))
-		cpacr_clear_set(0, CPACR_EL1_FPEN | CPACR_EL1_ZEN);
-	else
-		cpacr_clear_set(0, CPACR_EL1_FPEN);
+	__deactivate_cptr_traps(vcpu);
 	isb();
 
 	/* Write out the host state if it's in the registers */
@@ -566,6 +688,13 @@ static inline bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code)
 
 	*host_data_ptr(fp_owner) = FP_STATE_GUEST_OWNED;
 
+	/*
+	 * Re-enable traps necessary for the current state of the guest, e.g.
+	 * those enabled by a guest hypervisor. The ERET to the guest will
+	 * provide the necessary context synchronization.
+	 */
+	__activate_cptr_traps(vcpu);
+
 	return true;
 }