linux-kernel - [PATCH 1/4] KVM: arm64: change return value in arm64_check

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Message-ID: <20240405120108.11844-2-sebott@redhat.com>
Date: Fri,  5 Apr 2024 14:01:05 +0200
From: Sebastian Ott <sebott@...hat.com>
To: linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>
Subject: [PATCH 1/4] KVM: arm64: change return value in arm64_check_features()

arm64_check_features() returns -E2BIG to indicate the register's
feature set is a superset of the maximally-allowed register value.

The only caller of that function changes this to -EINVAL since
that's what userspace expects for invalid register writes.

In preparation of adding another caller for arm64_check_features()
that would need to do the same conversion just return -EINVAL
directly.

Signed-off-by: Sebastian Ott <sebott@...hat.com>
---
 arch/arm64/kvm/sys_regs.c | 18 ++++--------------
 1 file changed, 4 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index c9f4f387155f..131f5b0ca2b9 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1445,7 +1445,7 @@ static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,
  * considered the safe value regardless For register fields that are not in
  * writable, only the value in limit is considered the safe value.
  *
- * Return: 0 if all the fields are safe. Otherwise, return negative errno.
+ * Return: 0 if all the fields are safe. Otherwise, return -EINVAL.
  */
 static int arm64_check_features(struct kvm_vcpu *vcpu,
 				const struct sys_reg_desc *rd,
@@ -1464,7 +1464,7 @@ static int arm64_check_features(struct kvm_vcpu *vcpu,
 	 * only safe value is 0.
 	 */
 	if (sysreg_visible_as_raz(vcpu, rd))
-		return val ? -E2BIG : 0;
+		return val ? -EINVAL : 0;
 
 	ftr_reg = get_arm64_ftr_reg(id);
 	if (!ftr_reg)
@@ -1490,12 +1490,12 @@ static int arm64_check_features(struct kvm_vcpu *vcpu,
 			safe_val = kvm_arm64_ftr_safe_value(id, ftrp, f_val, f_lim);
 
 		if (safe_val != f_val)
-			return -E2BIG;
+			return -EINVAL;
 	}
 
 	/* For fields that are not writable, values in limit are the safe values. */
 	if ((val & ~mask) != (limit & ~mask))
-		return -E2BIG;
+		return -EINVAL;
 
 	return 0;
 }
@@ -1840,16 +1840,6 @@ static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
 		IDREG(vcpu->kvm, id) = val;
 
 	mutex_unlock(&vcpu->kvm->arch.config_lock);
-
-	/*
-	 * arm64_check_features() returns -E2BIG to indicate the register's
-	 * feature set is a superset of the maximally-allowed register value.
-	 * While it would be nice to precisely describe this to userspace, the
-	 * existing UAPI for KVM_SET_ONE_REG has it that invalid register
-	 * writes return -EINVAL.
-	 */
-	if (ret == -E2BIG)
-		ret = -EINVAL;
 	return ret;
 }
 
-- 
2.42.0