linux-kernel - [PATCH v3 04/14] KVM: selftests: Assert that vcpu_{g,s}et

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Message-ID: <20241009154953.1073471-5-seanjc@google.com>
Date: Wed,  9 Oct 2024 08:49:43 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Paolo Bonzini <pbonzini@...hat.com>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Sean Christopherson <seanjc@...gle.com>, Andrew Jones <ajones@...tanamicro.com>, 
	James Houghton <jthoughton@...gle.com>
Subject: [PATCH v3 04/14] KVM: selftests: Assert that vcpu_{g,s}et_reg() won't truncate

Assert that the register being read/written by vcpu_{g,s}et_reg() is no
larger than a uint64_t, i.e. that a selftest isn't unintentionally
truncating the value being read/written.

Ideally, the assert would be done at compile-time, but that would limit
the checks to hardcoded accesses and/or require fancier compile-time
assertion infrastructure to filter out dynamic usage.

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/include/kvm_util.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 287a3ec06df4..4c4e5a847f67 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -707,6 +707,8 @@ static inline uint64_t vcpu_get_reg(struct kvm_vcpu *vcpu, uint64_t id)
 	uint64_t val;
 	struct kvm_one_reg reg = { .id = id, .addr = (uint64_t)&val };
 
+	TEST_ASSERT(KVM_REG_SIZE(id) <= sizeof(val), "Reg %lx too big", id);
+
 	vcpu_ioctl(vcpu, KVM_GET_ONE_REG, &reg);
 	return val;
 }
@@ -714,6 +716,8 @@ static inline void vcpu_set_reg(struct kvm_vcpu *vcpu, uint64_t id, uint64_t val
 {
 	struct kvm_one_reg reg = { .id = id, .addr = (uint64_t)&val };
 
+	TEST_ASSERT(KVM_REG_SIZE(id) <= sizeof(val), "Reg %lx too big", id);
+
 	vcpu_ioctl(vcpu, KVM_SET_ONE_REG, &reg);
 }
 
-- 
2.47.0.rc0.187.ge670bccf7e-goog