linux-kernel - [PATCH v2 1/9] KVM: arm64: vgic-v3: Fix some error codes when setting RDIST base

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Date:   Thu, 14 Jan 2021 11:37:00 +0100
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu, maz@...nel.org, drjones@...hat.com
Cc:     alexandru.elisei@....com, james.morse@....com,
        julien.thierry.kdev@...il.com, suzuki.poulose@....com,
        shuah@...nel.org, pbonzini@...hat.com
Subject: [PATCH v2 1/9] KVM: arm64: vgic-v3: Fix some error codes when setting RDIST base

KVM_DEV_ARM_VGIC_GRP_ADDR group doc says we should return
-EEXIST in case the base address of the redist is already set.
We currently return -EINVAL.

However we need to return -EINVAL in case a legacy REDIST address
is attempted to be set while REDIST_REGIONS were set. This case
is discriminated by looking at the count field.

Signed-off-by: Eric Auger <eric.auger@...hat.com>

---

v1 -> v2:
- simplify the check sequence
---
 arch/arm64/kvm/vgic/vgic-mmio-v3.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 15a6c98ee92f..013b737b658f 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -791,10 +791,6 @@ static int vgic_v3_insert_redist_region(struct kvm *kvm, uint32_t index,
 	size_t size = count * KVM_VGIC_V3_REDIST_SIZE;
 	int ret;
 
-	/* single rdist region already set ?*/
-	if (!count && !list_empty(rd_regions))
-		return -EINVAL;
-
 	/* cross the end of memory ? */
 	if (base + size < base)
 		return -EINVAL;
@@ -805,11 +801,14 @@ static int vgic_v3_insert_redist_region(struct kvm *kvm, uint32_t index,
 	} else {
 		rdreg = list_last_entry(rd_regions,
 					struct vgic_redist_region, list);
-		if (index != rdreg->index + 1)
-			return -EINVAL;
 
-		/* Cannot add an explicitly sized regions after legacy region */
-		if (!rdreg->count)
+		if ((!count) != (!rdreg->count))
+			return -EINVAL; /* Mix REDIST and REDIST_REGION */
+
+		if (!count)
+			return -EEXIST;
+
+		if (index != rdreg->index + 1)
 			return -EINVAL;
 	}
 
-- 
2.21.3