Subject: [PATCH v3 3/6] KVM: arm: vgic: Only use the virtual state when userspace accesses enable bits

From: Marc Zyngier <[email-masked]>
Date: Wed, 22 Apr 2020 17:18:41 +0100

There is no point in accessing the HW when writing to any of the
ISENABLER/ICENABLER 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.

Reported-by: James Morse <[email-masked]>
Tested-by: James Morse <[email-masked]>
Reviewed-by: James Morse <[email-masked]>
Signed-off-by: Marc Zyngier <[email-masked]>
---
 virt/kvm/arm/vgic/vgic-mmio-v2.c |  6 +++--
 virt/kvm/arm/vgic/vgic-mmio-v3.c | 16 +++++++-----
 virt/kvm/arm/vgic/vgic-mmio.c    | 42 ++++++++++++++++++++++++++++++++
 virt/kvm/arm/vgic/vgic-mmio.h    |  8 ++++++
 4 files changed, 64 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
index d63881f60e1a5..f51c6e939c761 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
@@ -409,10 +409,12 @@ static const struct vgic_register_region vgic_v2_dist_registers[] = {
 		NULL, vgic_mmio_uaccess_write_v2_group, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_SET,
-		vgic_mmio_read_enable, vgic_mmio_write_senable, NULL, NULL, 1,
+		vgic_mmio_read_enable, vgic_mmio_write_senable,
+		NULL, vgic_uaccess_write_senable, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ(GIC_DIST_ENABLE_CLEAR,
-		vgic_mmio_read_enable, vgic_mmio_write_cenable, NULL, NULL, 1,
+		vgic_mmio_read_enable, vgic_mmio_write_cenable,
+		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,
diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index f2b37a081f26a..416613f2400c5 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -538,10 +538,12 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
 		vgic_mmio_read_group, vgic_mmio_write_group, NULL, NULL, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISENABLER,
-		vgic_mmio_read_enable, vgic_mmio_write_senable, NULL, NULL, 1,
+		vgic_mmio_read_enable, vgic_mmio_write_senable,
+		NULL, vgic_uaccess_write_senable, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICENABLER,
-		vgic_mmio_read_enable, vgic_mmio_write_cenable, NULL, NULL, 1,
+		vgic_mmio_read_enable, vgic_mmio_write_cenable,
+	       NULL, vgic_uaccess_write_cenable, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISPENDR,
 		vgic_mmio_read_pending, vgic_mmio_write_spending,
@@ -609,11 +611,13 @@ static const struct vgic_register_region vgic_v3_rd_registers[] = {
 	REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_IGROUPR0,
 		vgic_mmio_read_group, vgic_mmio_write_group, 4,
 		VGIC_ACCESS_32bit),
-	REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_ISENABLER0,
-		vgic_mmio_read_enable, vgic_mmio_write_senable, 4,
+	REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ISENABLER0,
+		vgic_mmio_read_enable, vgic_mmio_write_senable,
+		NULL, vgic_uaccess_write_senable, 4,
 		VGIC_ACCESS_32bit),
-	REGISTER_DESC_WITH_LENGTH(SZ_64K + GICR_ICENABLER0,
-		vgic_mmio_read_enable, vgic_mmio_write_cenable, 4,
+	REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ICENABLER0,
+		vgic_mmio_read_enable, vgic_mmio_write_cenable,
+		NULL, vgic_uaccess_write_cenable, 4,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ISPENDR0,
 		vgic_mmio_read_pending, vgic_mmio_write_spending,
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
index b38e94e8f74ad..6e30034d14645 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.c
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -184,6 +184,48 @@ void vgic_mmio_write_cenable(struct kvm_vcpu *vcpu,
 	}
 }
 
+int vgic_uaccess_write_senable(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);
+		irq->enabled = true;
+		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
+
+		vgic_put_irq(vcpu->kvm, irq);
+	}
+
+	return 0;
+}
+
+int vgic_uaccess_write_cenable(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);
+		irq->enabled = false;
+		raw_spin_unlock_irqrestore(&irq->irq_lock, flags);
+
+		vgic_put_irq(vcpu->kvm, irq);
+	}
+
+	return 0;
+}
+
 unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
 				     gpa_t addr, unsigned int len)
 {
diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
index 30713a44e3faa..327d0a6938e4d 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.h
+++ b/virt/kvm/arm/vgic/vgic-mmio.h
@@ -138,6 +138,14 @@ void vgic_mmio_write_cenable(struct kvm_vcpu *vcpu,
 			     gpa_t addr, unsigned int len,
 			     unsigned long val);
 
+int vgic_uaccess_write_senable(struct kvm_vcpu *vcpu,
+			       gpa_t addr, unsigned int len,
+			       unsigned long val);
+
+int vgic_uaccess_write_cenable(struct kvm_vcpu *vcpu,
+			       gpa_t addr, unsigned int len,
+			       unsigned long val);
+
 unsigned long vgic_mmio_read_pending(struct kvm_vcpu *vcpu,
 				     gpa_t addr, unsigned int len);
 
-- 
2.26.1

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