linux-kernel - [PATCH for-6.8 2/5] KVM: LoongArch: Fix kvm_check_cpucfg incorrectly accepting bad CPUCFG IDs

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Date: Wed, 14 Feb 2024 18:15:54 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Paolo Bonzini <pbonzini@...hat.com>,
	Huacai Chen <chenhuacai@...nel.org>
Cc: Tianrui Zhao <zhaotianrui@...ngson.cn>,
	Bibo Mao <maobibo@...ngson.cn>,
	kvm@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	WANG Xuerui <git@...0n.name>
Subject: [PATCH for-6.8 2/5] KVM: LoongArch: Fix kvm_check_cpucfg incorrectly accepting bad CPUCFG IDs

From: WANG Xuerui <git@...0n.name>

The return value of _kvm_get_cpucfg is meant to be checked, but this
was not done, so bad CPUCFG IDs wrongly fall back to the default case
and 0 is returned.

Check the return value to fix the UAPI behavior.

While at it, also remove the redundant range check, because
_kvm_get_cpucfg already rejects all unrecognized input CPUCFG IDs.
It was also wrong and no-op, in the same way as the former identical
check in _kvm_get_cpucfg.

Fixes: db1ecca22edf ("LoongArch: KVM: Add LSX (128bit SIMD) support")
Signed-off-by: WANG Xuerui <git@...0n.name>
---
 arch/loongarch/kvm/vcpu.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index c4a592623da6..cc2332b056ba 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -328,12 +328,10 @@ static int _kvm_get_cpucfg(int id, u64 *v)
 static int kvm_check_cpucfg(int id, u64 val)
 {
 	u64 mask;
-	int ret = 0;
-
-	if (id < 0 && id >= KVM_MAX_CPUCFG_REGS)
-		return -EINVAL;
+	int ret;
 
-	if (_kvm_get_cpucfg(id, &mask))
+	ret = _kvm_get_cpucfg(id, &mask);
+	if (ret)
 		return ret;
 
 	switch (id) {
-- 
2.43.0