1 files changed, 40 insertions, 41 deletions

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 27701991886d..36106922b5d7 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -298,74 +298,73 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
 	return ret;
 }
 
-static int _kvm_get_cpucfg(int id, u64 *v)
+static int _kvm_get_cpucfg_mask(int id, u64 *v)
 {
-	int ret = 0;
-
-	if (id < 0 && id >= KVM_MAX_CPUCFG_REGS)
+	if (id < 0 || id >= KVM_MAX_CPUCFG_REGS)
 		return -EINVAL;
 
 	switch (id) {
 	case 2:
-		/* Return CPUCFG2 features which have been supported by KVM */
+		/* CPUCFG2 features unconditionally supported by KVM */
 		*v = CPUCFG2_FP     | CPUCFG2_FPSP  | CPUCFG2_FPDP     |
 		     CPUCFG2_FPVERS | CPUCFG2_LLFTP | CPUCFG2_LLFTPREV |
 		     CPUCFG2_LAM;
 		/*
-		 * If LSX is supported by CPU, it is also supported by KVM,
-		 * as we implement it.
+		 * For the ISA extensions listed below, if one is supported
+		 * by the host, then it is also supported by KVM.
 		 */
 		if (cpu_has_lsx)
 			*v |= CPUCFG2_LSX;
-		/*
-		 * if LASX is supported by CPU, it is also supported by KVM,
-		 * as we implement it.
-		 */
 		if (cpu_has_lasx)
 			*v |= CPUCFG2_LASX;
 
-		break;
+		return 0;
 	default:
-		ret = -EINVAL;
-		break;
+		/*
+		 * No restrictions on other valid CPUCFG IDs' values, but
+		 * CPUCFG data is limited to 32 bits as the LoongArch ISA
+		 * manual says (Volume 1, Section 2.2.10.5 "CPUCFG").
+		 */
+		*v = U32_MAX;
+		return 0;
 	}
-	return ret;
 }
 
 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;
+	u64 mask = 0;
 
-	if (_kvm_get_cpucfg(id, &mask))
+	ret = _kvm_get_cpucfg_mask(id, &mask);
+	if (ret)
 		return ret;
 
+	if (val & ~mask)
+		/* Unsupported features and/or the higher 32 bits should not be set */
+		return -EINVAL;
+
 	switch (id) {
 	case 2:
-		/* CPUCFG2 features checking */
-		if (val & ~mask)
-			/* The unsupported features should not be set */
-			ret = -EINVAL;
-		else if (!(val & CPUCFG2_LLFTP))
-			/* The LLFTP must be set, as guest must has a constant timer */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
-			/* Single and double float point must both be set when enable FP */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
-			/* FP should be set when enable LSX */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
-			/* LSX, FP should be set when enable LASX, and FP has been checked before. */
-			ret = -EINVAL;
-		break;
+		if (!(val & CPUCFG2_LLFTP))
+			/* Guests must have a constant timer */
+			return -EINVAL;
+		if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
+			/* Single and double float point must both be set when FP is enabled */
+			return -EINVAL;
+		if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
+			/* LSX architecturally implies FP but val does not satisfy that */
+			return -EINVAL;
+		if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
+			/* LASX architecturally implies LSX and FP but val does not satisfy that */
+			return -EINVAL;
+		return 0;
 	default:
-		break;
+		/*
+		 * Values for the other CPUCFG IDs are not being further validated
+		 * besides the mask check above.
+		 */
+		return 0;
 	}
-	return ret;
 }
 
 static int kvm_get_one_reg(struct kvm_vcpu *vcpu,
@@ -566,7 +565,7 @@ static int kvm_loongarch_get_cpucfg_attr(struct kvm_vcpu *vcpu,
 	uint64_t val;
 	uint64_t __user *uaddr = (uint64_t __user *)attr->addr;
 
-	ret = _kvm_get_cpucfg(attr->attr, &val);
+	ret = _kvm_get_cpucfg_mask(attr->attr, &val);
 	if (ret)
 		return ret;