[PATCH] KVM: arm64: vgic-v3: Clear pending bit in guest memory after synchronization

From: Zenghui Yu <yuzenghui@huawei.com>
To: <kvmarm@lists.cs.columbia.edu>
Cc: <maz@kernel.org>, <eric.auger@redhat.com>,
	<andre.przywara@arm.com>, <james.morse@arm.com>,
	<julien.thierry.kdev@gmail.com>, <suzuki.poulose@arm.com>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>, <wanghaibin.wang@huawei.com>,
	Zenghui Yu <yuzenghui@huawei.com>
Subject: [PATCH] KVM: arm64: vgic-v3: Clear pending bit in guest memory after synchronization
Date: Tue, 31 Mar 2020 11:12:45 +0800	[thread overview]
Message-ID: <20200331031245.1562-1-yuzenghui@huawei.com> (raw)

When LPI support is enabled at redistributor level, VGIC will potentially
load the correspond LPI penging table and sync it into the pending_latch.
To avoid keeping the 'consumed' pending bits lying around in guest memory
(though they're not used), let's clear them after synchronization.

The similar work had been done in vgic_v3_lpi_sync_pending_status().

Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
 virt/kvm/arm/vgic/vgic-its.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index d53d34a33e35..905760bfa404 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -435,6 +435,7 @@ static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
 
 	for (i = 0; i < nr_irqs; i++) {
 		int byte_offset, bit_nr;
+		bool status;
 
 		byte_offset = intids[i] / BITS_PER_BYTE;
 		bit_nr = intids[i] % BITS_PER_BYTE;
@@ -447,22 +448,32 @@ static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
 			ret = kvm_read_guest_lock(vcpu->kvm,
 						  pendbase + byte_offset,
 						  &pendmask, 1);
-			if (ret) {
-				kfree(intids);
-				return ret;
-			}
+			if (ret)
+				goto out;
 			last_byte_offset = byte_offset;
 		}
 
+		status = pendmask & (1 << bit_nr);
+
 		irq = vgic_get_irq(vcpu->kvm, NULL, intids[i]);
 		raw_spin_lock_irqsave(&irq->irq_lock, flags);
-		irq->pending_latch = pendmask & (1U << bit_nr);
+		irq->pending_latch = status;
 		vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
 		vgic_put_irq(vcpu->kvm, irq);
+
+		if (status) {
+			/* clear consumed data */
+			pendmask &= ~(1 << bit_nr);
+			ret = kvm_write_guest_lock(vcpu->kvm,
+						   pendbase + byte_offset,
+						   &pendmask, 1);
+			if (ret)
+				goto out;
+		}
 	}
 
+out:
 	kfree(intids);
-
 	return ret;
 }
 
-- 
2.19.1


