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From: Andre Przywara <andre.przywara@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>
Cc: Dave Martin <dave.martin@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org
Subject: [PATCH] KVM: arm: VGIC: properly initialise private IRQ affinity
Date: Wed,  6 Mar 2019 10:40:08 +0000	[thread overview]
Message-ID: <20190306104008.69414-1-andre.przywara@arm.com> (raw)

At the moment we initialise the target *mask* of a virtual IRQ to the
VCPU it belongs to, even though this mask is only defined for GICv2 and
quickly runs out of bits for many GICv3 guests.
This behaviour triggers an UBSAN complaint for more than 32 VCPUs:
------
[ 5659.462377] UBSAN: Undefined behaviour in virt/kvm/arm/vgic/vgic-init.c:223:21
[ 5659.471689] shift exponent 32 is too large for 32-bit type 'unsigned int'
------
Also for GICv3 guests the reporting of TARGET in the "vgic-state" debugfs
dump is wrong, due to this very same problem.

Fix both issues by only initialising vgic_irq->targets for a vGICv2 guest,
and by initialising vgic_irq->mpdir for vGICv3 guests instead. We can't
use the actual MPIDR for that, as the VCPU's system register is not
initialised at this point yet. This is not really an issue, as ->mpidr
is just used for the debugfs output and the IROUTER MMIO register, which
does not exist in redistributors (dealing with SGIs and PPIs).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reported-by: Dave Martin <dave.martin@arm.com>
---
 virt/kvm/arm/vgic/vgic-init.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 3bdb31eaed64..3172b2c916f1 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -220,7 +220,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
 		irq->intid = i;
 		irq->vcpu = NULL;
 		irq->target_vcpu = vcpu;
-		irq->targets = 1U << vcpu->vcpu_id;
 		kref_init(&irq->refcount);
 		if (vgic_irq_is_sgi(i)) {
 			/* SGIs */
@@ -231,10 +230,14 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
 			irq->config = VGIC_CONFIG_LEVEL;
 		}
 
-		if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
+		if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
 			irq->group = 1;
-		else
+			/* The actual MPIDR is not initialised at this point. */
+			irq->mpidr = 0;
+		} else {
 			irq->group = 0;
+			irq->targets = 1U << vcpu->vcpu_id;
+		}
 	}
 
 	if (!irqchip_in_kernel(vcpu->kvm))
-- 
2.17.1

WARNING: multiple messages have this Message-ID (diff)
From: Andre Przywara <andre.przywara@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>
Cc: Dave Martin <dave.martin@arm.com>,
	kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org
Subject: [PATCH] KVM: arm: VGIC: properly initialise private IRQ affinity
Date: Wed,  6 Mar 2019 10:40:08 +0000	[thread overview]
Message-ID: <20190306104008.69414-1-andre.przywara@arm.com> (raw)

At the moment we initialise the target *mask* of a virtual IRQ to the
VCPU it belongs to, even though this mask is only defined for GICv2 and
quickly runs out of bits for many GICv3 guests.
This behaviour triggers an UBSAN complaint for more than 32 VCPUs:
------
[ 5659.462377] UBSAN: Undefined behaviour in virt/kvm/arm/vgic/vgic-init.c:223:21
[ 5659.471689] shift exponent 32 is too large for 32-bit type 'unsigned int'
------
Also for GICv3 guests the reporting of TARGET in the "vgic-state" debugfs
dump is wrong, due to this very same problem.

Fix both issues by only initialising vgic_irq->targets for a vGICv2 guest,
and by initialising vgic_irq->mpdir for vGICv3 guests instead. We can't
use the actual MPIDR for that, as the VCPU's system register is not
initialised at this point yet. This is not really an issue, as ->mpidr
is just used for the debugfs output and the IROUTER MMIO register, which
does not exist in redistributors (dealing with SGIs and PPIs).

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reported-by: Dave Martin <dave.martin@arm.com>
---
 virt/kvm/arm/vgic/vgic-init.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c
index 3bdb31eaed64..3172b2c916f1 100644
--- a/virt/kvm/arm/vgic/vgic-init.c
+++ b/virt/kvm/arm/vgic/vgic-init.c
@@ -220,7 +220,6 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
 		irq->intid = i;
 		irq->vcpu = NULL;
 		irq->target_vcpu = vcpu;
-		irq->targets = 1U << vcpu->vcpu_id;
 		kref_init(&irq->refcount);
 		if (vgic_irq_is_sgi(i)) {
 			/* SGIs */
@@ -231,10 +230,14 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
 			irq->config = VGIC_CONFIG_LEVEL;
 		}
 
-		if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3)
+		if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
 			irq->group = 1;
-		else
+			/* The actual MPIDR is not initialised at this point. */
+			irq->mpidr = 0;
+		} else {
 			irq->group = 0;
+			irq->targets = 1U << vcpu->vcpu_id;
+		}
 	}
 
 	if (!irqchip_in_kernel(vcpu->kvm))
-- 
2.17.1


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             reply	other threads:[~2019-03-06 10:40 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-06 10:40 Andre Przywara [this message]
2019-03-06 10:40 ` [PATCH] KVM: arm: VGIC: properly initialise private IRQ affinity Andre Przywara
2019-03-06 11:42 ` Christophe de Dinechin
2019-03-06 11:51   ` Marc Zyngier
2019-03-06 11:51     ` Marc Zyngier
2019-03-06 11:52   ` Andre Przywara
2019-03-06 11:52     ` Andre Przywara

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