On Mon, 27 May 2024, Eric Wheeler wrote: > On Wed, 15 May 2024, Mikulas Patocka wrote: > > Hi > > > > Some NVMe devices may be formatted with extra 64 bytes of metadata per > > sector. > > > > Here I'm submitting for review dm-crypt patches that make it possible to > > use per-sector metadata for authenticated encryption. With these patches, > > dm-crypt can run directly on the top of a NVMe device, without using > > dm-integrity. These patches increase write throughput twice, because there > > is no write to the dm-integrity journal. > > > > An example how to use it (so far, there is no support in the userspace > > cryptsetup tool): > > > > # nvme format /dev/nvme1 -n 1 -lbaf=4 > > # dmsetup create cr --table '0 1048576 crypt > > capi:authenc(hmac(sha256),cbc(aes))-essiv:sha256 > > 01b11af6b55f76424fd53fb66667c301466b2eeaf0f39fd36d26e7fc4f52ade2de4228e996f5ae2fe817ce178e77079d28e4baaebffbcd3e16ae4f36ef217298 > > 0 /dev/nvme1n1 0 2 integrity:32:aead sector_size:4096' > > Thats really an amazing feature, and I think your implementation is simple > and elegant. Somehow reminds me of 520/528-byte sectors that big > commercial filers use, but in a way the Linux could use. > > Questions: > > - I see you are using 32-bytes of AEAD data (out of 64). Is AEAD always > 32-bytes, or can it vary by crypto mechanism? It varies. I.e. if you use hmac(sha512), full 64 bytes will be used. > - What drive are you using? Western Digital SN840 WUS4BA119DSP3X3 > I am curious what your `nvme id-ns` output > looks like. Do you have 64 in the `ms` value? > > # nvme id-ns /dev/nvme0n1 | grep lbaf > nlbaf : 0 > nulbaf : 0 > lbaf 0 : ms:0 lbads:9 rp:0 (in use) > ^ ^512b Yes, I have this: lbaf 0 : ms:0 lbads:9 rp:0 lbaf 1 : ms:8 lbads:9 rp:0 lbaf 2 : ms:0 lbads:12 rp:0 lbaf 3 : ms:8 lbads:12 rp:0 lbaf 4 : ms:64 lbads:12 rp:0 (in use) Mikulas > -- > Eric Wheeler
