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From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Julien Grall <julien@xen.org>, Andre Przywara <Andre.Przywara@arm.com>
Subject: [PATCH v3 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits
Date: Wed, 22 Apr 2020 17:18:42 +0100	[thread overview]
Message-ID: <20200422161844.3848063-5-maz@kernel.org> (raw)
In-Reply-To: <20200422161844.3848063-1-maz@kernel.org>

There is no point in accessing the HW when writing to any of the
ISPENDR/ICPENDR registers from userspace, as only the guest should
be allowed to change the HW state.

Introduce new userspace-specific accessors that deal solely with
the virtual state. Note that the API differs from that of GICv3,
where userspace exclusively uses ISPENDR to set the state. Too
bad we can't reuse it.

Fixes: 82e40f558de56 ("KVM: arm/arm64: vgic-v2: Handle SGI bits in GICD_I{S,C}PENDR0 as WI")
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 virt/kvm/arm/vgic/vgic-mmio-v2.c |  6 ++-
 virt/kvm/arm/vgic/vgic-mmio.c    | 86 ++++++++++++++++++++++++--------
 virt/kvm/arm/vgic/vgic-mmio.h    |  8 +++
 3 files changed, 76 insertions(+), 24 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
index f51c6e939c761..a016f07adc281 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
@@ -417,10 +417,12 @@ static const struct vgic_register_region vgic_v2_dist_registers[] = {
 		NULL, vgic_uaccess_write_cenable, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_PENDING_SET,
-		vgic_mmio_read_pending, vgic_mmio_write_spending, NULL, NULL, 1,
+		vgic_mmio_read_pending, vgic_mmio_write_spending,
+		NULL, vgic_uaccess_write_spending, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_PENDING_CLEAR,
-		vgic_mmio_read_pending, vgic_mmio_write_cpending, NULL, NULL, 1,
+		vgic_mmio_read_pending, vgic_mmio_write_cpending,
+		NULL, vgic_uaccess_write_cpending, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ACTIVE_SET,
 		vgic_mmio_read_active, vgic_mmio_write_sactive,
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
index 6e30034d14645..b2d73fc0d1ef4 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.c
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -261,17 +261,6 @@ unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
 	return value;
 }
 
-/* Must be called with irq->irq_lock held */
-static void vgic_hw_irq_spending(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
-				 bool is_uaccess)
-{
-	if (is_uaccess)
-		return;
-
-	irq->pending_latch = true;
-	vgic_irq_set_phys_active(irq, true);
-}
-
 static bool is_vgic_v2_sgi(struct kvm_vcpu *vcpu, struct vgic_irq *irq)
 {
 	return (vgic_irq_is_sgi(irq->intid) &&
@@ -282,7 +271,6 @@ void vgic_mmio_write_spending(struct kvm_vcpu *vcpu,
 			      gpa_t addr, unsigned int len,
 			      unsigned long val)
 {
-	bool is_uaccess = !kvm_get_running_vcpu();
 	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
 	int i;
 	unsigned long flags;
@@ -312,22 +300,48 @@ void vgic_mmio_write_spending(struct kvm_vcpu *vcpu,
 			continue;
 		}
 
+		irq->pending_latch = true;
 		if (irq->hw)
-			vgic_hw_irq_spending(vcpu, irq, is_uaccess);
-		else
-			irq->pending_latch = true;
+			vgic_irq_set_phys_active(irq, true);
+
 		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
 		vgic_put_irq(vcpu->kvm, irq);
 	}
 }
 
-/* Must be called with irq->irq_lock held */
-static void vgic_hw_irq_cpending(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
-				 bool is_uaccess)
+int vgic_uaccess_write_spending(struct kvm_vcpu *vcpu,
+				gpa_t addr, unsigned int len,
+				unsigned long val)
 {
-	if (is_uaccess)
-		return;
+	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
+	int i;
+	unsigned long flags;
+
+	for_each_set_bit(i, &val, len * 8) {
+		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
 
+		raw_spin_lock_irqsave(&irq->irq_lock, flags);
+		irq->pending_latch = true;
+
+		/*
+		 * GICv2 SGIs are terribly broken. We can't restore
+		 * the source of the interrupt, so just pick the vcpu
+		 * itself as the source...
+		 */
+		if (is_vgic_v2_sgi(vcpu, irq))
+			irq->source |= BIT(vcpu->vcpu_id);
+
+		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
+
+		vgic_put_irq(vcpu->kvm, irq);
+	}
+
+	return 0;
+}
+
+/* Must be called with irq->irq_lock held */
+static void vgic_hw_irq_cpending(struct kvm_vcpu *vcpu, struct vgic_irq *irq)
+{
 	irq->pending_latch = false;
 
 	/*
@@ -350,7 +364,6 @@ void vgic_mmio_write_cpending(struct kvm_vcpu *vcpu,
 			      gpa_t addr, unsigned int len,
 			      unsigned long val)
 {
-	bool is_uaccess = !kvm_get_running_vcpu();
 	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
 	int i;
 	unsigned long flags;
@@ -381,7 +394,7 @@ void vgic_mmio_write_cpending(struct kvm_vcpu *vcpu,
 		}
 
 		if (irq->hw)
-			vgic_hw_irq_cpending(vcpu, irq, is_uaccess);
+			vgic_hw_irq_cpending(vcpu, irq);
 		else
 			irq->pending_latch = false;
 
@@ -390,6 +403,35 @@ void vgic_mmio_write_cpending(struct kvm_vcpu *vcpu,
 	}
 }
 
+int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu,
+				gpa_t addr, unsigned int len,
+				unsigned long val)
+{
+	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
+	int i;
+	unsigned long flags;
+
+	for_each_set_bit(i, &val, len * 8) {
+		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
+
+		raw_spin_lock_irqsave(&irq->irq_lock, flags);
+		/*
+		 * More fun with GICv2 SGIs! If we're clearing one of them
+		 * from userspace, which source vcpu to clear? Let's not
+		 * even think of it, and blow the whole set.
+		 */
+		if (is_vgic_v2_sgi(vcpu, irq))
+			irq->source = 0;
+
+		irq->pending_latch = false;
+
+		raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+
+		vgic_put_irq(vcpu->kvm, irq);
+	}
+
+	return 0;
+}
 
 /*
  * If we are fiddling with an IRQ's active state, we have to make sure the IRQ
diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
index 327d0a6938e4d..fefcca2b14dc7 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.h
+++ b/virt/kvm/arm/vgic/vgic-mmio.h
@@ -157,6 +157,14 @@ void vgic_mmio_write_cpending(struct kvm_vcpu *vcpu,
 			      gpa_t addr, unsigned int len,
 			      unsigned long val);
 
+int vgic_uaccess_write_spending(struct kvm_vcpu *vcpu,
+				gpa_t addr, unsigned int len,
+				unsigned long val);
+
+int vgic_uaccess_write_cpending(struct kvm_vcpu *vcpu,
+				gpa_t addr, unsigned int len,
+				unsigned long val);
+
 unsigned long vgic_mmio_read_active(struct kvm_vcpu *vcpu,
 				    gpa_t addr, unsigned int len);
 
-- 
2.26.1

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  parent reply	other threads:[~2020-04-22 16:19 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-22 16:18 [PATCH v3 0/6] KVM: arm: vgic fixes for 5.7 Marc Zyngier
2020-04-22 16:18 ` [PATCH v3 1/6] KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER Marc Zyngier
2020-04-22 16:18 ` [PATCH v3 2/6] KVM: arm: vgic: Synchronize the whole guest on GIC{D, R}_I{S, C}ACTIVER read Marc Zyngier
2020-04-22 16:18 ` [PATCH v3 3/6] KVM: arm: vgic: Only use the virtual state when userspace accesses enable bits Marc Zyngier
2020-04-22 16:18 ` Marc Zyngier [this message]
2020-04-23 11:05   ` [PATCH v3 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits James Morse
2020-04-22 16:18 ` [PATCH v3 5/6] KVM: arm64: vgic-v3: Retire all pending LPIs on vcpu destroy Marc Zyngier
2020-04-23 11:35   ` James Morse
2020-04-23 11:57     ` Zenghui Yu
2020-04-23 14:34       ` James Morse
2020-04-23 12:03     ` Marc Zyngier
2020-04-23 12:18       ` Zenghui Yu
2020-04-23 14:34       ` James Morse
2020-04-23 15:13         ` Marc Zyngier
2020-04-22 16:18 ` [PATCH v3 6/6] KVM: arm64: vgic-its: Fix memory leak on the error path of vgic_add_lpi() Marc Zyngier

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