KVM: arm64: unify code to prepare traps

There are 2 functions to calculate traps via HCR_EL2:
* kvm_init_sysreg() called via KVM_RUN (before the 1st run or when
  the pid changes)
* vcpu_reset_hcr() called via KVM_ARM_VCPU_INIT

To unify these 2 and to support traps that are dependent on the
ID register configuration, move the code from vcpu_reset_hcr()
to sys_regs.c and call it via kvm_init_sysreg().

We still have to keep the non-FWB handling stuff in vcpu_reset_hcr().
Also the initialization with HCR_GUEST_FLAGS is kept there but guarded
by !vcpu_has_run_once() to ensure that previous calculated values
don't get overwritten.

While at it rename kvm_init_sysreg() to kvm_calculate_traps() to
better reflect what it's doing.
Signed-off-by: Sebastian Ott <sebott@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240619174036.483943-7-oliver.upton@linux.devSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

arch/arm64/include/asm/kvm_emulate.h

@@ -69,39 +69,17 @@ static __always_inline bool vcpu_el1_is_32bit(struct kvm_vcpu *vcpu)
 
 static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
 {
-	vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
-	if (has_vhe() || has_hvhe())
-		vcpu->arch.hcr_el2 |= HCR_E2H;
-	if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) {
-		/* route synchronous external abort exceptions to EL2 */
-		vcpu->arch.hcr_el2 |= HCR_TEA;
-		/* trap error record accesses */
-		vcpu->arch.hcr_el2 |= HCR_TERR;
-	}
+	if (!vcpu_has_run_once(vcpu))
+		vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
 
-	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB)) {
-		vcpu->arch.hcr_el2 |= HCR_FWB;
-	} else {
-		/*
-		 * For non-FWB CPUs, we trap VM ops (HCR_EL2.TVM) until M+C
-		 * get set in SCTLR_EL1 such that we can detect when the guest
-		 * MMU gets turned on and do the necessary cache maintenance
-		 * then.
-		 */
+	/*
+	 * For non-FWB CPUs, we trap VM ops (HCR_EL2.TVM) until M+C
+	 * get set in SCTLR_EL1 such that we can detect when the guest
+	 * MMU gets turned on and do the necessary cache maintenance
+	 * then.
+	 */
+	if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
 		vcpu->arch.hcr_el2 |= HCR_TVM;
-	}
-
-	if (cpus_have_final_cap(ARM64_HAS_EVT) &&
-	    !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE))
-		vcpu->arch.hcr_el2 |= HCR_TID4;
-	else
-		vcpu->arch.hcr_el2 |= HCR_TID2;
-
-	if (vcpu_el1_is_32bit(vcpu))
-		vcpu->arch.hcr_el2 &= ~HCR_RW;
-
-	if (kvm_has_mte(vcpu->kvm))
-		vcpu->arch.hcr_el2 |= HCR_ATA;
 }
 
 static inline unsigned long *vcpu_hcr(struct kvm_vcpu *vcpu)

arch/arm64/include/asm/kvm_host.h

@@ -1120,7 +1120,7 @@ int __init populate_nv_trap_config(void);
 bool lock_all_vcpus(struct kvm *kvm);
 void unlock_all_vcpus(struct kvm *kvm);
 
-void kvm_init_sysreg(struct kvm_vcpu *);
+void kvm_calculate_traps(struct kvm_vcpu *vcpu);
 
 /* MMIO helpers */
 void kvm_mmio_write_buf(void *buf, unsigned int len, unsigned long data);

arch/arm64/kvm/arm.c

@@ -797,7 +797,7 @@ int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
 	 * This needs to happen after NV has imposed its own restrictions on
 	 * the feature set
 	 */
-	kvm_init_sysreg(vcpu);
+	kvm_calculate_traps(vcpu);
 
 	ret = kvm_timer_enable(vcpu);
 	if (ret)

arch/arm64/kvm/sys_regs.c

@@ -4069,11 +4069,33 @@ int kvm_vm_ioctl_get_reg_writable_masks(struct kvm *kvm, struct reg_mask_range *
 	return 0;
 }
 
-void kvm_init_sysreg(struct kvm_vcpu *vcpu)
+static void vcpu_set_hcr(struct kvm_vcpu *vcpu)
 {
 	struct kvm *kvm = vcpu->kvm;
 
-	mutex_lock(&kvm->arch.config_lock);
+	if (has_vhe() || has_hvhe())
+		vcpu->arch.hcr_el2 |= HCR_E2H;
+	if (cpus_have_final_cap(ARM64_HAS_RAS_EXTN)) {
+		/* route synchronous external abort exceptions to EL2 */
+		vcpu->arch.hcr_el2 |= HCR_TEA;
+		/* trap error record accesses */
+		vcpu->arch.hcr_el2 |= HCR_TERR;
+	}
+
+	if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
+		vcpu->arch.hcr_el2 |= HCR_FWB;
+
+	if (cpus_have_final_cap(ARM64_HAS_EVT) &&
+	    !cpus_have_final_cap(ARM64_MISMATCHED_CACHE_TYPE))
+		vcpu->arch.hcr_el2 |= HCR_TID4;
+	else
+		vcpu->arch.hcr_el2 |= HCR_TID2;
+
+	if (vcpu_el1_is_32bit(vcpu))
+		vcpu->arch.hcr_el2 &= ~HCR_RW;
+
+	if (kvm_has_mte(vcpu->kvm))
+		vcpu->arch.hcr_el2 |= HCR_ATA;
 
 	/*
 	 * In the absence of FGT, we cannot independently trap TLBI
@@ -4082,6 +4104,14 @@ void kvm_init_sysreg(struct kvm_vcpu *vcpu)
 	 */
 	if (!kvm_has_feat(kvm, ID_AA64ISAR0_EL1, TLB, OS))
 		vcpu->arch.hcr_el2 |= HCR_TTLBOS;
+}
+
+void kvm_calculate_traps(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+
+	mutex_lock(&kvm->arch.config_lock);
+	vcpu_set_hcr(vcpu);
 
 	if (cpus_have_final_cap(ARM64_HAS_HCX)) {
 		vcpu->arch.hcrx_el2 = HCRX_GUEST_FLAGS;