[PATCH v3 08/19] KVM: arm64: ITS: Interpret MAPD Size field and check related errors

[Auger Eric]

Hi Andre,

On 17/03/2017 16:03, Andre Przywara wrote:
> Hi,
> 
> On 06/03/17 11:34, Eric Auger wrote:
>> 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 nb_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 at redhat.com>
>>
>> ---
>> ---
>>  include/linux/irqchip/arm-gic-v3.h |  2 ++
>>  virt/kvm/arm/vgic/vgic-its.c       | 14 +++++++++++++-
>>  2 files changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
>> index d81f10f..a7a5548 100644
>> --- a/include/linux/irqchip/arm-gic-v3.h
>> +++ b/include/linux/irqchip/arm-gic-v3.h
>> @@ -338,9 +338,11 @@
>>  #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
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> index 6d84508..56bcd92 100644
>> --- a/virt/kvm/arm/vgic/vgic-its.c
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -99,6 +99,7 @@ struct its_device {
>>  
>>  	/* the head for the list of ITTEs */
>>  	struct list_head itt_head;
>> +	u32 nb_eventid_bits;
>>  	u32 device_id;
>>  };
>>  
>> @@ -177,6 +178,7 @@ static struct its_ite *find_ite(struct vgic_its *its, u32 device_id,
>>  #define GIC_LPI_OFFSET 8192
>>  
>>  #define VITS_ESZ 8
>> +#define VITS_TYPER_IDBITS 0xF
> 
> Alone for consistency reasons I'd use "16" here and subtract one upon
> encoding this into the TYPER register.
OK done
> 
>>  
>>  /*
>>   * Finds and returns a collection in the ITS collection table.
>> @@ -400,7 +402,7 @@ 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 |= VITS_TYPER_IDBITS << GITS_TYPER_IDBITS_SHIFT;
>>  	reg |= (VITS_ESZ - 1) << GITS_TYPER_ITT_ENTRY_SIZE_SHIFT;
>>  
>>  	return extract_bytes(reg, addr & 7, len);
>> @@ -560,6 +562,7 @@ static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
>>  #define its_cmd_get_collection(cmd)	its_cmd_mask_field(cmd, 2,  0, 16)
>>  #define its_cmd_get_target_addr(cmd)	its_cmd_mask_field(cmd, 2, 16, 32)
>>  #define its_cmd_get_validbit(cmd)	its_cmd_mask_field(cmd, 2, 63,  1)
>> +#define its_cmd_get_size(cmd)		its_cmd_mask_field(cmd, 1, 0,  5)
> 
> Can you please move this up to be in order with the other fields?
done
> 
>>  /*
>>   * The DISCARD command frees an Interrupt Translation Table Entry (ITTE).
>> @@ -745,6 +748,9 @@ 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 >= (2 << device->nb_eventid_bits))
> 
> And I'd find it less confusing to hold the actual bit size in
> nb_eventid_bits (and abstract from the particular encoding in TYPER).
> That would avoid this slightly odd (2 << ...) here, for instance.
OK I replaced nb_eventid_bits by nb_eventids which corresponds to the
the max number of eventids for this device

More than odd, the shift is completely wrong. Now I use BIT_ULL() as you
mentioned later on.

The only drawback is that when flushing the DTE I need to use ilog2 to
encode the size field again.
> 
>> +		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
>> @@ -825,11 +831,15 @@ 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);
>> +	size_t size = its_cmd_get_size(its_cmd);
> 
> If you add 1 here, you'd make clear that this is an encoding property.
done

Thanks

Eric

> 
> Cheers,
> Andre.
> 
>>  	struct its_device *device;
>>  
>>  	if (!vgic_its_check_id(its, its->baser_device_table, device_id))
>>  		return E_ITS_MAPD_DEVICE_OOR;
>>  
>> +	if (valid && size > VITS_TYPER_IDBITS)
>> +		return E_ITS_MAPD_ITTSIZE_OOR;
>> +
>>  	device = find_its_device(its, device_id);
>>  
>>  	/*
>> @@ -852,6 +862,8 @@ static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
>>  		return -ENOMEM;
>>  
>>  	device->device_id = device_id;
>> +	device->nb_eventid_bits = size + 1;
>> +
>>  	INIT_LIST_HEAD(&device->itt_head);
>>  
>>  	list_add_tail(&device->dev_list, &its->device_list);
>>