Let's try to detect the actual THP size and use it as default block size
(unless the page size of the backend indicates that THP don't apply).
Always allow to set a block size of 1 MiB, but warn if the configured block
size is smaller than the default. Handle large block sizes better, avoiding
a virtio-spec violation and optimizing address auto-detection.

For existing setups (x86-64), the default block size won't change (was, and
will be 2 MiB on anonymous memory). For existing x86-64 setups, the address
auto-detection won't change in relevant setups (esp., anonymous memory
and hugetlbfs with 2 MiB pages and no manual configuration of the block
size). I don't see the need for compatibility handling (especially, as
virtio-mem is still not considered production-ready).

Most of this is a preparation for future architectures, using hugetlbfs
to full extend, and using manually configured, larger block sizes
(relevant for vfio in the future).

v1 -> v2:
- Reordered patches to have fixes upfront
- Tweaked some patch descriptions
- "virtio-mem: Check that "memaddr" is multiples of the block size"
-- Renamed to "virtio-mem: Make sure "addr" is always multiples of the
   block size"
- "virtio-mem: Make sure "usable_region_size" is always multiples of the
   block size"
-- Added

v1 -> v2:
- Tweak some patch descriptions
- "virtio-mem: Probe THP size to determine default block size"
-- Beautify THP detection a bit.
-- Assume THP might only get used if the memory backend page size corresponds
   to the real hostpage size.
-- Use virtio_mem_default_block_size(RAMBlock *rb) to handle selection
   of the default block size for a RAMBlock.
-- Implement virtio_mem_get_block_size() as preparation for patch #5
- "memory-device: Add get_min_alignment() callback"
-- Simplify documentation.
- "virito-mem: Implement get_min_alignment()"
-- Simplify due to changes in patch #1.

David Hildenbrand (6):
  virtio-mem: Make sure "addr" is always multiples of the block size
  virtio-mem: Make sure "usable_region_size" is always multiples of the
    block size
  virtio-mem: Probe THP size to determine default block size
  memory-device: Support big alignment requirements
  memory-device: Add get_min_alignment() callback
  virito-mem: Implement get_min_alignment()

 hw/mem/memory-device.c         |  20 ++++--
 hw/virtio/virtio-mem-pci.c     |   7 ++
 hw/virtio/virtio-mem.c         | 113 +++++++++++++++++++++++++++++++--
 include/hw/mem/memory-device.h |  10 +++
 4 files changed, 140 insertions(+), 10 deletions(-)

-- 
2.26.2

On 08.10.20 10:30, David Hildenbrand wrote:
> 
> 
> Let's try to detect the actual THP size and use it as default block size
> (unless the page size of the backend indicates that THP don't apply).
> Always allow to set a block size of 1 MiB, but warn if the configured block
> size is smaller than the default. Handle large block sizes better, avoiding
> a virtio-spec violation and optimizing address auto-detection.
> 
> For existing setups (x86-64), the default block size won't change (was, and
> will be 2 MiB on anonymous memory). For existing x86-64 setups, the address
> auto-detection won't change in relevant setups (esp., anonymous memory
> and hugetlbfs with 2 MiB pages and no manual configuration of the block
> size). I don't see the need for compatibility handling (especially, as
> virtio-mem is still not considered production-ready).
> 
> Most of this is a preparation for future architectures, using hugetlbfs
> to full extend, and using manually configured, larger block sizes
> (relevant for vfio in the future).

Ping.

-- 
Thanks,

David / dhildenb

On 22.10.20 10:10, David Hildenbrand wrote:
> On 08.10.20 10:30, David Hildenbrand wrote:
>>
>>
>> Let's try to detect the actual THP size and use it as default block size
>> (unless the page size of the backend indicates that THP don't apply).
>> Always allow to set a block size of 1 MiB, but warn if the configured block
>> size is smaller than the default. Handle large block sizes better, avoiding
>> a virtio-spec violation and optimizing address auto-detection.
>>
>> For existing setups (x86-64), the default block size won't change (was, and
>> will be 2 MiB on anonymous memory). For existing x86-64 setups, the address
>> auto-detection won't change in relevant setups (esp., anonymous memory
>> and hugetlbfs with 2 MiB pages and no manual configuration of the block
>> size). I don't see the need for compatibility handling (especially, as
>> virtio-mem is still not considered production-ready).
>>
>> Most of this is a preparation for future architectures, using hugetlbfs
>> to full extend, and using manually configured, larger block sizes
>> (relevant for vfio in the future).
> 
> Ping.
> 

Ping, MST?

-- 
Thanks,

David / dhildenb

On Mon, Nov 02, 2020 at 01:20:11PM +0100, David Hildenbrand wrote:
> On 22.10.20 10:10, David Hildenbrand wrote:
> > On 08.10.20 10:30, David Hildenbrand wrote:
> > > 
> > > 
> > > Let's try to detect the actual THP size and use it as default block size
> > > (unless the page size of the backend indicates that THP don't apply).
> > > Always allow to set a block size of 1 MiB, but warn if the configured block
> > > size is smaller than the default. Handle large block sizes better, avoiding
> > > a virtio-spec violation and optimizing address auto-detection.
> > > 
> > > For existing setups (x86-64), the default block size won't change (was, and
> > > will be 2 MiB on anonymous memory). For existing x86-64 setups, the address
> > > auto-detection won't change in relevant setups (esp., anonymous memory
> > > and hugetlbfs with 2 MiB pages and no manual configuration of the block
> > > size). I don't see the need for compatibility handling (especially, as
> > > virtio-mem is still not considered production-ready).
> > > 
> > > Most of this is a preparation for future architectures, using hugetlbfs
> > > to full extend, and using manually configured, larger block sizes
> > > (relevant for vfio in the future).
> > 
> > Ping.
> > 
> 
> Ping, MST?

Applied, thanks!

> -- 
> Thanks,
> 
> David / dhildenb