linux-kernel - [PATCH v3 1/7] KVM: x86: check validity of argument to KVM_SET_MP

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Date:   Mon, 22 Aug 2022 13:06:53 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     mlevitsk@...hat.com, seanjc@...gle.com
Subject: [PATCH v3 1/7] KVM: x86: check validity of argument to KVM_SET_MP_STATE

An invalid argument to KVM_SET_MP_STATE has no effect other than making the
vCPU fail to run at the next KVM_RUN.  Since it is extremely unlikely that
any userspace is relying on it, fail with -EINVAL just like for other
architectures.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d7374d768296..4d719ba21553 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10652,7 +10652,8 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
 	case KVM_MP_STATE_INIT_RECEIVED:
 		break;
 	default:
-		return -EINTR;
+		WARN_ON_ONCE(1);
+		break;
 	}
 	return 1;
 }
@@ -11093,9 +11094,22 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 
 	vcpu_load(vcpu);
 
-	if (!lapic_in_kernel(vcpu) &&
-	    mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
+	switch (mp_state->mp_state) {
+	case KVM_MP_STATE_UNINITIALIZED:
+	case KVM_MP_STATE_HALTED:
+	case KVM_MP_STATE_AP_RESET_HOLD:
+	case KVM_MP_STATE_INIT_RECEIVED:
+	case KVM_MP_STATE_SIPI_RECEIVED:
+		if (!lapic_in_kernel(vcpu))
+			goto out;
+		break;
+
+	case KVM_MP_STATE_RUNNABLE:
+		break;
+
+	default:
 		goto out;
+	}
 
 	/*
 	 * KVM_MP_STATE_INIT_RECEIVED means the processor is in
-- 
2.31.1