KVM: arm64: Fix SMPRI_EL1/TPIDR2_EL0 trapping on VHE

The trapping of SMPRI_EL1 and TPIDR2_EL0 currently only really
work on nVHE, as only this mode uses the fine-grained trapping
that controls these two registers.

Move the trapping enable/disable code into
__{de,}activate_traps_common(), allowing it to be called when it
actually matters on VHE, and remove the flipping of EL2 control
for TPIDR2_EL0, which only affects the host access of this
register.

Fixes: 861262ab ("KVM: arm64: Handle SME host state when running guests")
Reported-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/86bkpqer4z.wl-maz@kernel.org

arch/arm64/kvm/hyp/include/hyp/switch.h

@@ -87,6 +87,17 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu)
 
 	vcpu->arch.mdcr_el2_host = read_sysreg(mdcr_el2);
 	write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
+
+	if (cpus_have_final_cap(ARM64_SME)) {
+		sysreg_clear_set_s(SYS_HFGRTR_EL2,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK,
+				   0);
+		sysreg_clear_set_s(SYS_HFGWTR_EL2,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK,
+				   0);
+	}
 }
 
 static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu)
@@ -96,6 +107,15 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu)
 	write_sysreg(0, hstr_el2);
 	if (kvm_arm_support_pmu_v3())
 		write_sysreg(0, pmuserenr_el0);
+
+	if (cpus_have_final_cap(ARM64_SME)) {
+		sysreg_clear_set_s(SYS_HFGRTR_EL2, 0,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK);
+		sysreg_clear_set_s(SYS_HFGWTR_EL2, 0,
+				   HFGxTR_EL2_nSMPRI_EL1_MASK |
+				   HFGxTR_EL2_nTPIDR2_EL0_MASK);
+	}
 }
 
 static inline void ___activate_traps(struct kvm_vcpu *vcpu)

arch/arm64/kvm/hyp/nvhe/switch.c

@@ -55,18 +55,6 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 	write_sysreg(val, cptr_el2);
 	write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el2);
 
-	if (cpus_have_final_cap(ARM64_SME)) {
-		val = read_sysreg_s(SYS_HFGRTR_EL2);
-		val &= ~(HFGxTR_EL2_nTPIDR2_EL0_MASK |
-			 HFGxTR_EL2_nSMPRI_EL1_MASK);
-		write_sysreg_s(val, SYS_HFGRTR_EL2);
-
-		val = read_sysreg_s(SYS_HFGWTR_EL2);
-		val &= ~(HFGxTR_EL2_nTPIDR2_EL0_MASK |
-			 HFGxTR_EL2_nSMPRI_EL1_MASK);
-		write_sysreg_s(val, SYS_HFGWTR_EL2);
-	}
-
 	if (cpus_have_final_cap(ARM64_WORKAROUND_SPECULATIVE_AT)) {
 		struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
 
@@ -110,20 +98,6 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 
 	write_sysreg(this_cpu_ptr(&kvm_init_params)->hcr_el2, hcr_el2);
 
-	if (cpus_have_final_cap(ARM64_SME)) {
-		u64 val;
-
-		val = read_sysreg_s(SYS_HFGRTR_EL2);
-		val |= HFGxTR_EL2_nTPIDR2_EL0_MASK |
-			HFGxTR_EL2_nSMPRI_EL1_MASK;
-		write_sysreg_s(val, SYS_HFGRTR_EL2);
-
-		val = read_sysreg_s(SYS_HFGWTR_EL2);
-		val |= HFGxTR_EL2_nTPIDR2_EL0_MASK |
-			HFGxTR_EL2_nSMPRI_EL1_MASK;
-		write_sysreg_s(val, SYS_HFGWTR_EL2);
-	}
-
 	cptr = CPTR_EL2_DEFAULT;
 	if (vcpu_has_sve(vcpu) && (vcpu->arch.fp_state == FP_STATE_GUEST_OWNED))
 		cptr |= CPTR_EL2_TZ;

arch/arm64/kvm/hyp/vhe/switch.c

@@ -63,10 +63,6 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
 		__activate_traps_fpsimd32(vcpu);
 	}
 
-	if (cpus_have_final_cap(ARM64_SME))
-		write_sysreg(read_sysreg(sctlr_el2) & ~SCTLR_ELx_ENTP2,
-			     sctlr_el2);
-
 	write_sysreg(val, cpacr_el1);
 
 	write_sysreg(__this_cpu_read(kvm_hyp_vector), vbar_el1);
@@ -88,10 +84,6 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
 	 */
 	asm(ALTERNATIVE("nop", "isb", ARM64_WORKAROUND_SPECULATIVE_AT));
 
-	if (cpus_have_final_cap(ARM64_SME))
-		write_sysreg(read_sysreg(sctlr_el2) | SCTLR_ELx_ENTP2,
-			     sctlr_el2);
-
 	write_sysreg(CPACR_EL1_DEFAULT, cpacr_el1);
 
 	if (!arm64_kernel_unmapped_at_el0())