KVM: arm64: vgic-its: Interpret MAPD Size field and check related errors

Up to now the MAPD's ITT size field has been ignored. It encodes
the number of eventid bit minus 1. It should be used to check
the eventid when a MAPTI command is issued on a device. Let's
store the number of eventid bits in the its_device and do the
check on MAPTI. Also make sure the ITT size field does
not exceed the GITS_TYPER IDBITS field.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

include/linux/irqchip/arm-gic-v3.h

@@ -347,9 +347,11 @@
 #define E_ITS_INT_UNMAPPED_INTERRUPT		0x010307
 #define E_ITS_CLEAR_UNMAPPED_INTERRUPT		0x010507
 #define E_ITS_MAPD_DEVICE_OOR			0x010801
+#define E_ITS_MAPD_ITTSIZE_OOR			0x010802
 #define E_ITS_MAPC_PROCNUM_OOR			0x010902
 #define E_ITS_MAPC_COLLECTION_OOR		0x010903
 #define E_ITS_MAPTI_UNMAPPED_DEVICE		0x010a04
+#define E_ITS_MAPTI_ID_OOR			0x010a05
 #define E_ITS_MAPTI_PHYSICALID_OOR		0x010a06
 #define E_ITS_INV_UNMAPPED_INTERRUPT		0x010c07
 #define E_ITS_INVALL_UNMAPPED_COLLECTION	0x010d09

virt/kvm/arm/vgic/vgic-its.c

@@ -103,6 +103,7 @@ struct its_device {
 
 	/* the head for the list of ITTEs */
 	struct list_head itt_head;
+	u32 num_eventid_bits;
 	u32 device_id;
 };
 
@@ -224,6 +225,8 @@ static struct its_ite *find_ite(struct vgic_its *its, u32 device_id,
 
 #define GIC_LPI_OFFSET 8192
 
+#define VITS_TYPER_IDBITS 16
+
 /*
  * Finds and returns a collection in the ITS collection table.
  * Must be called with the its_lock mutex held.
@@ -424,7 +427,7 @@ static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
 	 * DevBits low - as least for the time being.
 	 */
 	reg |= 0x0f << GITS_TYPER_DEVBITS_SHIFT;
-	reg |= 0x0f << GITS_TYPER_IDBITS_SHIFT;
+	reg |= GIC_ENCODE_SZ(VITS_TYPER_IDBITS, 5) << GITS_TYPER_IDBITS_SHIFT;
 	reg |= GIC_ENCODE_SZ(abi->ite_esz, 4) << GITS_TYPER_ITT_ENTRY_SIZE_SHIFT;
 
 	return extract_bytes(reg, addr & 7, len);
@@ -595,6 +598,7 @@ static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
 
 #define its_cmd_get_command(cmd)	its_cmd_mask_field(cmd, 0,  0,  8)
 #define its_cmd_get_deviceid(cmd)	its_cmd_mask_field(cmd, 0, 32, 32)
+#define its_cmd_get_size(cmd)		(its_cmd_mask_field(cmd, 1,  0,  5) + 1)
 #define its_cmd_get_id(cmd)		its_cmd_mask_field(cmd, 1,  0, 32)
 #define its_cmd_get_physical_id(cmd)	its_cmd_mask_field(cmd, 1, 32, 32)
 #define its_cmd_get_collection(cmd)	its_cmd_mask_field(cmd, 2,  0, 16)
@@ -785,6 +789,9 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
 	if (!device)
 		return E_ITS_MAPTI_UNMAPPED_DEVICE;
 
+	if (event_id >= BIT_ULL(device->num_eventid_bits))
+		return E_ITS_MAPTI_ID_OOR;
+
 	if (its_cmd_get_command(its_cmd) == GITS_CMD_MAPTI)
 		lpi_nr = its_cmd_get_physical_id(its_cmd);
 	else
@@ -865,11 +872,15 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
 {
 	u32 device_id = its_cmd_get_deviceid(its_cmd);
 	bool valid = its_cmd_get_validbit(its_cmd);
+	u8 num_eventid_bits = its_cmd_get_size(its_cmd);
 	struct its_device *device;
 
 	if (!vgic_its_check_id(its, its->baser_device_table, device_id))
 		return E_ITS_MAPD_DEVICE_OOR;
 
+	if (valid && num_eventid_bits > VITS_TYPER_IDBITS)
+		return E_ITS_MAPD_ITTSIZE_OOR;
+
 	device = find_its_device(its, device_id);
 
 	/*
@@ -892,6 +903,8 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
 		return -ENOMEM;
 
 	device->device_id = device_id;
+	device->num_eventid_bits = num_eventid_bits;
+
 	INIT_LIST_HEAD(&device->itt_head);
 
 	list_add_tail(&device->dev_list, &its->device_list);