Merge branch kvm-arm64/psci/cpu_on into kvmarm-master/next

PSCI fixes from Oliver Upton:
- Plug race on reset
- Ensure that a pending reset is applied before userspace accesses
- Reject PSCI requests with illegal affinity bits

* kvm-arm64/psci/cpu_on:
  selftests: KVM: Introduce psci_cpu_on_test
  KVM: arm64: Enforce reserved bits for PSCI target affinities
  KVM: arm64: Handle PSCI resets before userspace touches vCPU state
  KVM: arm64: Fix read-side race on updates to vcpu reset state

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

3 files changed, 30 insertions, 9 deletions

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index fd9a6bcf797f..1decdec70102 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1216,6 +1216,14 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		if (copy_from_user(&reg, argp, sizeof(reg)))
 			break;
 
+		/*
+		 * We could owe a reset due to PSCI. Handle the pending reset
+		 * here to ensure userspace register accesses are ordered after
+		 * the reset.
+		 */
+		if (kvm_check_request(KVM_REQ_VCPU_RESET, vcpu))
+			kvm_reset_vcpu(vcpu);
+
 		if (ioctl == KVM_SET_ONE_REG)
 			r = kvm_arm_set_reg(vcpu, &reg);
 		else
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index db4056ecccfd..74c47d420253 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -59,6 +59,12 @@ static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
 	kvm_vcpu_kick(vcpu);
 }
 
+static inline bool kvm_psci_valid_affinity(struct kvm_vcpu *vcpu,
+					   unsigned long affinity)
+{
+	return !(affinity & ~MPIDR_HWID_BITMASK);
+}
+
 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 {
 	struct vcpu_reset_state *reset_state;
@@ -66,9 +72,9 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
 	struct kvm_vcpu *vcpu = NULL;
 	unsigned long cpu_id;
 
-	cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK;
-	if (vcpu_mode_is_32bit(source_vcpu))
-		cpu_id &= ~((u32) 0);
+	cpu_id = smccc_get_arg1(source_vcpu);
+	if (!kvm_psci_valid_affinity(source_vcpu, cpu_id))
+		return PSCI_RET_INVALID_PARAMS;
 
 	vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
 
@@ -126,6 +132,9 @@ static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 	target_affinity = smccc_get_arg1(vcpu);
 	lowest_affinity_level = smccc_get_arg2(vcpu);
 
+	if (!kvm_psci_valid_affinity(vcpu, target_affinity))
+		return PSCI_RET_INVALID_PARAMS;
+
 	/* Determine target affinity mask */
 	target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
 	if (!target_affinity_mask)
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 08fd487d5f95..5ce36b0a3343 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -210,10 +210,16 @@ static bool vcpu_allowed_register_width(struct kvm_vcpu *vcpu)
  */
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 {
+	struct vcpu_reset_state reset_state;
 	int ret;
 	bool loaded;
 	u32 pstate;
 
+	mutex_lock(&vcpu->kvm->lock);
+	reset_state = vcpu->arch.reset_state;
+	WRITE_ONCE(vcpu->arch.reset_state.reset, false);
+	mutex_unlock(&vcpu->kvm->lock);
+
 	/* Reset PMU outside of the non-preemptible section */
 	kvm_pmu_vcpu_reset(vcpu);
 
@@ -276,8 +282,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	 * Additional reset state handling that PSCI may have imposed on us.
 	 * Must be done after all the sys_reg reset.
 	 */
-	if (vcpu->arch.reset_state.reset) {
-		unsigned long target_pc = vcpu->arch.reset_state.pc;
+	if (reset_state.reset) {
+		unsigned long target_pc = reset_state.pc;
 
 		/* Gracefully handle Thumb2 entry point */
 		if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
@@ -286,13 +292,11 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 		}
 
 		/* Propagate caller endianness */
-		if (vcpu->arch.reset_state.be)
+		if (reset_state.be)
 			kvm_vcpu_set_be(vcpu);
 
 		*vcpu_pc(vcpu) = target_pc;
-		vcpu_set_reg(vcpu, 0, vcpu->arch.reset_state.r0);
-
-		vcpu->arch.reset_state.reset = false;
+		vcpu_set_reg(vcpu, 0, reset_state.r0);
 	}
 
 	/* Reset timer */