Fast initialization of secure HMB
The present disclosure generally relates to data storage devices and related methods that use secure host memory buffers (HMBs) and low latency operations. A controller of the data storage device is configured to access the HMB, where the HMB stores a Merkle Tree. When the HMB is initialized, the controller determines a number of hash levels of the Merkle Tree. Each hash level of the Merkle Tree comprises one or more hashes. When storing location data in a target data block of the Merkle Tree, the controller is configured to initialize only the hashes along a path between a top hash and the target data block. Each hash along the path has a non-initialized hash coupled to a common hash. The non-initialized hash is programmed with a non-initialized bit, such that only the relevant hashes and data blocks are initialized.
1. A data storage device, comprising:
one or more memory devices; and
a controller coupled to the one or more memory devices, the controller configured to:
access a host memory buffer (HMB) of a host device, wherein the HMB comprises a Merkle Tree comprising a plurality of data blocks and a total number of hash levels, wherein each hash level of the Merkle Tree comprises at least one hash of a plurality of hashes, and wherein each hash of a last hash level is coupled to a data block of the plurality of data blocks;
determine a first number of hash levels of the Merkle Tree to initialize, the first number of hash levels being less than the total number of hash levels;
initialize the first number of hash levels;
initialize one or more first hashes on a path between a top hash level and a target data block of the plurality of data blocks, wherein initializing the one or more first hashes comprises programming a non-initialized bit to a non-initialized hash off the path; and
remove the non-initialized bit from the non-initialized hash when the non-initialized hash is initialized.
2. The data storage device of claim 1 , wherein initializing the one or more first hashes on the path comprises programming a signature to each of the one or more first hashes.
3. The data storage device of claim 1 , wherein the Merkle Tree is a binary hash tree, and wherein the total number of hash levels is at least two hash levels.
4. The data storage device of claim 3 , wherein a first hash level has a first number of hashes and a second hash level has a second number of hashes, and wherein the second number of hashes is equal to two times the first number of hashes.
5. The data storage device of claim 4 , wherein a first hash of the first number of hashes is coupled to a second hash and a third hash of the second number of hashes.
6. The data storage device of claim 5 , wherein a signature of the first hash is calculated based on the second hash and the third hash.
7. A data storage device, comprising:
one or more memory devices; and
a controller coupled to the one or more memory devices, the controller configured to:
determine a target data block of a plurality of data blocks of a Merkle Tree of a host memory buffer (HMB) associated with the data of a read request, the Merkle Tree further comprising a number of hash levels, wherein each hash level comprises at least one hash of a plurality of hashes, and wherein a last hash level is coupled to the plurality of data blocks;
read the target data block and one or more first hashes on a path between a top hash level and the target data block;
determine if any of the one or more first hashes comprises a non-initialized bit, wherein at least one of the one or more first hashes comprising the non-initialized bit returns a fixed pattern, and wherein none of the one or more first hashes comprise the non-initialized bit returns the target data block; and
return either the fixed pattern or the target data block.
8. The data storage device of claim 7 , wherein:
each hash of the last hash level is coupled to a data block of the plurality of data blocks;
the plurality of data blocks comprises a plurality of entries of a flash translation layer (FTL) table; and
the target data block comprises one or more entries corresponding to a location of the data of a read request stored in the one or more memory devices.
9. The data storage device of claim 7 , wherein returning the fixed pattern comprises sending an indication, and wherein the indication indicates that the target data block comprises garbage data.
10. The data storage device of claim 7 , wherein a first hash level of the number of hash levels has a first number of hashes and a second hash level of the number of hash levels disposed adjacent to the first hash level has a second number of hashes, and wherein the second number of hashes is equal to two times the first number of hashes.
11. The data storage device of claim 10 , wherein the reading comprises:
reading a first hash of the second hash level, the first hash being coupled to the data block;
fetching a second hash of the second hash level, wherein the first hash and the second hash are coupled to a third hash of the first hash level; and
calculating a third signature of the third hash based on a first signature of the first hash and a second signature of the second hash.
12. The data storage device of claim 11 , wherein the reading further comprises:
comparing a calculated top hash signature to the target data block; and
returning data of the target data block when the calculated top hash signature matches the target data block.
13. A data storage device, comprising:
one or more memory devices;
a controller coupled to the one or more memory devices, the controller comprising:
means to access a host memory buffer (HMB) of a host device, wherein the HMB comprises a Merkle Tree;
means to determine a total number of hash levels of the Merkle Tree, the total number of hash levels being at least two, wherein each hash level comprises at least one hash of a plurality of hashes, and wherein each hash of a last hash level is coupled to a data block;
means to initialize a first number of hash levels, wherein the first number of hash levels is less than the total number of hash levels; and
means to set a non-initialized bit to each hash of a second number of hash levels.
14. The data storage device of claim 13 , wherein the controller further comprises:
means to determine a path between a top hash and a target data block, wherein one or more first hashes on the path are initialized, and wherein one or more second hashes off the path are set with the non-initialized bit;
means to determine if the one or more second hashes comprise the non-initialized bit; and
means to remove the non-initialized bit upon initializing a hash of the one or more second hashes or a hash of the second number of hash levels.
15. The data storage device of claim 13 , wherein the controller further comprises means to calculate a calculated top hash signature, wherein the means to calculate the calculated top hash signature comprises calculating a signature of the one or more first hashes.
16. The data storage device of claim 15 , wherein the controller further comprises means to send a verification upon determining that a target data block matches the calculated top hash signature.
17. The data storage device of claim 13 , wherein the total number of hash levels is variable based on a determined initialization speed.