linux-kernel - [PATCH 7/9] KVM: arm/arm64: vgic-its: free caches when GITS

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Date:   Mon, 25 Sep 2017 15:34:36 +0200
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,
        marc.zyngier@....com, cdall@...aro.org, peter.maydell@...aro.org,
        andre.przywara@....com, wanghaibin.wang@...wei.com
Cc:     wu.wubin@...wei.com
Subject: [PATCH 7/9] KVM: arm/arm64: vgic-its: free caches when GITS_BASER Valid bit is cleared

When the GITS_BASER<n>.Valid gets cleared, the data structures in
guest RAM are not provisionned anymore. The device, collection
and LPI lists stored in the in-kernel ITS represent the same
information in some form of cache. So let's void the cache.

Signed-off-by: Eric Auger <eric.auger@...hat.com>
---
 virt/kvm/arm/vgic/vgic-its.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 3f4deb4..e280e62 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -1471,8 +1471,9 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
 				      unsigned long val)
 {
 	const struct vgic_its_abi *abi = vgic_its_get_abi(its);
-	u64 entry_size, device_type;
+	u64 entry_size;
 	u64 reg, *regptr, clearbits = 0;
+	int type;
 
 	/* When GITS_CTLR.Enable is 1, we ignore write accesses. */
 	if (its->enabled)
@@ -1482,12 +1483,12 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
 	case 0:
 		regptr = &its->baser_device_table;
 		entry_size = abi->dte_esz;
-		device_type = GITS_BASER_TYPE_DEVICE;
+		type = GITS_BASER_TYPE_DEVICE;
 		break;
 	case 1:
 		regptr = &its->baser_coll_table;
 		entry_size = abi->cte_esz;
-		device_type = GITS_BASER_TYPE_COLLECTION;
+		type = GITS_BASER_TYPE_COLLECTION;
 		clearbits = GITS_BASER_INDIRECT;
 		break;
 	default:
@@ -1499,10 +1500,24 @@ static void vgic_mmio_write_its_baser(struct kvm *kvm,
 	reg &= ~clearbits;
 
 	reg |= (entry_size - 1) << GITS_BASER_ENTRY_SIZE_SHIFT;
-	reg |= device_type << GITS_BASER_TYPE_SHIFT;
+	reg |= (u64)type << GITS_BASER_TYPE_SHIFT;
 	reg = vgic_sanitise_its_baser(reg);
 
 	*regptr = reg;
+
+	if (reg & GITS_BASER_VALID)
+		return;
+
+	switch (type) {
+	case GITS_BASER_TYPE_DEVICE:
+		vgic_its_free_device_list(kvm, its);
+		break;
+	case GITS_BASER_TYPE_COLLECTION:
+		vgic_its_free_collection_list(kvm, its);
+		break;
+	default:
+		break;
+	}
 }
 
 static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,
-- 
2.5.5