[PATCH v4 18/22] KVM: arm64: ITS: Collection table save/restore

[Auger Eric]

Hi Marc,

On 10/04/2017 11:55, Marc Zyngier wrote:
> On 27/03/17 10:31, Eric Auger wrote:
>> The flush path copies the collection entries into guest RAM
>> at the GPA specified in the BASER register. This obviously
>> requires the BASER to be set. The last written element
>> is a dummy collection table entry.
>>
>> We do not index by collection ID as the collection entry
>> can fit into 8 bytes while containing the collection ID.
>>
>> On restore path we re-allocate the collection objects.
>>
>> Signed-off-by: Eric Auger <eric.auger at redhat.com>
>>
>> ---
>>
>> v3 -> v4:
>> - replaced u64 *ptr by gpa_t gpa
>> - check the collection does not exist before allocating it
>>
>> v1 -> v2:
>> - reword commit message and directly use 8 as entry size
>> - no kvm parameter anymore
>> - add helper for flush/restore cte
>> - table size computed here
>> - add le64/cpu conversions
>> ---
>>  virt/kvm/arm/vgic/vgic-its.c | 99 +++++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 97 insertions(+), 2 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> index 8eaeba4..df984b6 100644
>> --- a/virt/kvm/arm/vgic/vgic-its.c
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -1828,13 +1828,89 @@ static int vgic_its_restore_device_tables(struct vgic_its *its)
>>  	return -ENXIO;
>>  }
>>  
>> +static int vgic_its_flush_cte(struct vgic_its *its,
>> +			      struct its_collection *collection, gpa_t gpa)
> 
> Given that the pendent of this function is name ..._restore_..., should
> this be called ..._save_... ?
> 
>> +{
>> +	u64 val;
>> +	int ret;
>> +
>> +	val = ((u64)1 << 63 | ((u64)collection->target_addr << 16) |
>> +	       collection->collection_id);
> 
> Please provide some #defines that describe the encoding. This will be
> specially useful if we need to export this to userspace (KVM/TCG
> interoperability?).
> 
>> +	val = cpu_to_le64(val);
>> +	ret = kvm_write_guest(its->dev->kvm, gpa, &val, 8);
>> +	return ret;
>> +}
>> +
>> +static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, bool *valid)
>> +{
>> +	struct its_collection *collection;
>> +	u32 target_addr;
>> +	u32 coll_id;
>> +	u64 val;
>> +	int ret;
>> +
>> +	*valid = false;
>> +
>> +	ret = kvm_read_guest(its->dev->kvm, gpa, &val, 8);
>> +	if (ret)
>> +		return ret;
>> +	val = le64_to_cpu(val);
>> +	*valid = val & BIT_ULL(63);
>> +
>> +	if (!*valid)
>> +		return 0;
>> +
>> +	target_addr = (u32)(val >> 16);
> 
> u32?
At the moment its_collection.target_addr is u32 and corresponds to the
PE number. Only GITS_TYPER.PTA = 0 is supported.

Or do I miss something?

Thanks

Eric
> 
>> +	coll_id = val & 0xFFFF;
> 
> Same comment about the various shifts/masks.
> 
>> +
>> +	collection = find_collection(its, coll_id);
>> +	if (collection)
>> +		return -EEXIST;
>> +	ret = vgic_its_alloc_collection(its, &collection, coll_id);
>> +	if (ret)
>> +		return ret;
>> +	collection->target_addr = target_addr;
>> +	return 0;
>> +}
>> +
>>  /**
>>   * vgic_its_flush_collection_table - flush the collection table into
>>   * guest RAM
>>   */
>>  static int vgic_its_flush_collection_table(struct vgic_its *its)
>>  {
>> -	return -ENXIO;
>> +	struct its_collection *collection;
>> +	u64 val;
>> +	gpa_t gpa;
>> +	size_t max_size, filled = 0;
>> +	int ret;
>> +
>> +	gpa = BASER_ADDRESS(its->baser_coll_table);
>> +	if (!gpa)
>> +		return 0;
>> +
>> +	max_size = GITS_BASER_NR_PAGES(its->baser_coll_table) * SZ_64K;
>> +
>> +	list_for_each_entry(collection, &its->collection_list, coll_list) {
>> +		if (filled == max_size)
>> +			return -ENOSPC;
>> +		ret = vgic_its_flush_cte(its, collection, gpa);
>> +		if (ret)
>> +			return ret;
>> +		gpa += 8;
>> +		filled += 8;
> 
> This "8" should be extracted from the BASER register itself (Entry_Size).
> 
>> +	}
>> +
>> +	if (filled == max_size)
>> +		return 0;
>> +
>> +	/*
>> +	 * table is not fully filled, add a last dummy element
>> +	 * with valid bit unset
>> +	 */
>> +	val = 0;
>> +	ret = kvm_write_guest(its->dev->kvm, gpa, &val, 8);
>> +	return ret;
>>  }
>>  
>>  /**
>> @@ -1844,7 +1920,26 @@ static int vgic_its_flush_collection_table(struct vgic_its *its)
>>   */
>>  static int vgic_its_restore_collection_table(struct vgic_its *its)
>>  {
>> -	return -ENXIO;
>> +	size_t max_size, read = 0;
>> +	gpa_t gpa;
>> +	int ret;
>> +
>> +	gpa = BASER_ADDRESS(its->baser_coll_table);
>> +	if (!gpa)
>> +		return 0;
>> +
>> +	max_size = GITS_BASER_NR_PAGES(its->baser_coll_table) * SZ_64K;
>> +
>> +	while (read < max_size) {
>> +		bool valid;
>> +
>> +		ret = vgic_its_restore_cte(its, gpa, &valid);
>> +		if (!valid || ret)
>> +			break;
>> +		gpa += 8;
>> +		read += 8;
>> +	}
>> +	return ret;
>>  }
>>  
>>  /**
>>
> 
> Thanks,
> 
> 	M.
>