| Message ID | 20240208060851.154129-1-ebiggers@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | da215b089b5d4ff30745c59922b54b309d55a5d8 |
| Headers | show |
| Series | [riscv/for-next] crypto: riscv - parallelize AES-CBC decryption | expand |
On Feb 8, 2024, at 14:08, Eric Biggers <ebiggers@kernel.org> wrote: > From: Eric Biggers <ebiggers@google.com> > > Since CBC decryption is parallelizable, make the RISC-V implementation > of AES-CBC decryption process multiple blocks at a time, instead of > processing the blocks one by one. This should improve performance. > > Signed-off-by: Eric Biggers <ebiggers@google.com> > --- > arch/riscv/crypto/aes-riscv64-zvkned.S | 24 +++++++++++++++--------- > 1 file changed, 15 insertions(+), 9 deletions(-) > > diff --git a/arch/riscv/crypto/aes-riscv64-zvkned.S b/arch/riscv/crypto/aes-riscv64-zvkned.S > index 78d4e1186c074..43541aad6386c 100644 > --- a/arch/riscv/crypto/aes-riscv64-zvkned.S > +++ b/arch/riscv/crypto/aes-riscv64-zvkned.S > @@ -132,33 +132,39 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) > addi INP, INP, 16 > addi OUTP, OUTP, 16 > addi LEN, LEN, -16 > bnez LEN, 1b > > vse32.v v16, (IVP) // Store next IV > ret > .endm > > .macro aes_cbc_decrypt keylen > + srli LEN, LEN, 2 // Convert LEN from bytes to words > vle32.v v16, (IVP) // Load IV > 1: > - vle32.v v17, (INP) // Load ciphertext block > - vmv.v.v v18, v17 // Save ciphertext block > - aes_decrypt v17, \keylen // Decrypt > - vxor.vv v17, v17, v16 // XOR with IV or prev ciphertext block > - vse32.v v17, (OUTP) // Store plaintext block > - vmv.v.v v16, v18 // Next "IV" is prev ciphertext block > - addi INP, INP, 16 > - addi OUTP, OUTP, 16 > - addi LEN, LEN, -16 > + vsetvli t0, LEN, e32, m4, ta, ma > + vle32.v v20, (INP) // Load ciphertext blocks > + vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks > + addi t1, t0, -4 > + vslidedown.vx v24, v20, t1 // Save last ciphertext block Do we need to setup the `e32, len=t0` for next IV? I think we only need 128bit IV (with VL=4). > + aes_decrypt v20, \keylen // Decrypt the blocks > + vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks > + vse32.v v20, (OUTP) // Store plaintext blocks > + vmv.v.v v16, v24 // Next "IV" is last ciphertext block Same VL issue here. > + slli t1, t0, 2 // Words to bytes > + add INP, INP, t1 > + add OUTP, OUTP, t1 > + sub LEN, LEN, t0 > bnez LEN, 1b > > + vsetivli zero, 4, e32, m1, ta, ma > vse32.v v16, (IVP) // Store next IV > ret > .endm > > // void aes_cbc_encrypt_zvkned(const struct crypto_aes_ctx *key, > // const u8 *in, u8 *out, size_t len, u8 iv[16]); > // > // |len| must be nonzero and a multiple of 16 (AES_BLOCK_SIZE). > SYM_FUNC_START(aes_cbc_encrypt_zvkned) > aes_begin KEYP, 128f, 192f > > base-commit: cb4ede926134a65bc3bf90ed58dace8451d7e759 > -- > 2.43.0 >
On Sat, Feb 10, 2024 at 11:25:27PM +0800, Jerry Shih wrote: > > .macro aes_cbc_decrypt keylen > > + srli LEN, LEN, 2 // Convert LEN from bytes to words > > vle32.v v16, (IVP) // Load IV > > 1: > > - vle32.v v17, (INP) // Load ciphertext block > > - vmv.v.v v18, v17 // Save ciphertext block > > - aes_decrypt v17, \keylen // Decrypt > > - vxor.vv v17, v17, v16 // XOR with IV or prev ciphertext block > > - vse32.v v17, (OUTP) // Store plaintext block > > - vmv.v.v v16, v18 // Next "IV" is prev ciphertext block > > - addi INP, INP, 16 > > - addi OUTP, OUTP, 16 > > - addi LEN, LEN, -16 > > + vsetvli t0, LEN, e32, m4, ta, ma > > + vle32.v v20, (INP) // Load ciphertext blocks > > + vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks > > + addi t1, t0, -4 > > + vslidedown.vx v24, v20, t1 // Save last ciphertext block > > Do we need to setup the `e32, len=t0` for next IV? > I think we only need 128bit IV (with VL=4). > > > + aes_decrypt v20, \keylen // Decrypt the blocks > > + vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks > > + vse32.v v20, (OUTP) // Store plaintext blocks > > + vmv.v.v v16, v24 // Next "IV" is last ciphertext block > > Same VL issue here. It's true that the vslidedown.vx and vmv.v.v only need vl=4. But it also works fine with vl unchanged. It just results in some extra data being moved in the registers. My hypothesis is that this is going to be faster than having the three extra instructions per loop iteration to change the vl to 4 twice. I still have no real hardware to test on, so I have no quantitative data. All I can do is go with my instinct which is that the shorter version will be better. If you have access to a real CPU that supports the RISC-V vector crypto extensions, I'd be interested in the performance you get from each variant. (Of course, different RISC-V CPU implementations may have quite different performance characteristics, so that still won't be definitive.) Here is the alternative variant given as a diff from this patch: diff --git a/arch/riscv/crypto/aes-riscv64-zvkned.S b/arch/riscv/crypto/aes-riscv64-zvkned.S index 43541aad6386c..ef380771f606a 100644 --- a/arch/riscv/crypto/aes-riscv64-zvkned.S +++ b/arch/riscv/crypto/aes-riscv64-zvkned.S @@ -146,10 +146,13 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) vle32.v v20, (INP) // Load ciphertext blocks vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks addi t1, t0, -4 + vsetivli zero, 4, e32, m4, ta, ma vslidedown.vx v24, v20, t1 // Save last ciphertext block + vsetvli t0, LEN, e32, m4, ta, ma aes_decrypt v20, \keylen // Decrypt the blocks vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks vse32.v v20, (OUTP) // Store plaintext blocks + vsetivli zero, 4, e32, m4, ta, ma vmv.v.v v16, v24 // Next "IV" is last ciphertext block slli t1, t0, 2 // Words to bytes add INP, INP, t1 @@ -157,7 +160,6 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) sub LEN, LEN, t0 bnez LEN, 1b - vsetivli zero, 4, e32, m1, ta, ma vse32.v v16, (IVP) // Store next IV ret .endm A third variant would be to just replace vmv.v.v with vmv1r.v. In general, this level of micro-optimization probably needs to be wait until there are a variety of CPUs to test on. We know that parallelizing the algorithms is helpful, so we should do that, as this patch does. But the effects of small variations in the instruction sequences are currently unclear. - Eric
On Feb 11, 2024, at 02:12, Eric Biggers <ebiggers@kernel.org> wrote: > On Sat, Feb 10, 2024 at 11:25:27PM +0800, Jerry Shih wrote: >>> .macro aes_cbc_decrypt keylen >>> + srli LEN, LEN, 2 // Convert LEN from bytes to words >>> vle32.v v16, (IVP) // Load IV >>> 1: >>> - vle32.v v17, (INP) // Load ciphertext block >>> - vmv.v.v v18, v17 // Save ciphertext block >>> - aes_decrypt v17, \keylen // Decrypt >>> - vxor.vv v17, v17, v16 // XOR with IV or prev ciphertext block >>> - vse32.v v17, (OUTP) // Store plaintext block >>> - vmv.v.v v16, v18 // Next "IV" is prev ciphertext block >>> - addi INP, INP, 16 >>> - addi OUTP, OUTP, 16 >>> - addi LEN, LEN, -16 >>> + vsetvli t0, LEN, e32, m4, ta, ma >>> + vle32.v v20, (INP) // Load ciphertext blocks >>> + vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks >>> + addi t1, t0, -4 >>> + vslidedown.vx v24, v20, t1 // Save last ciphertext block >> >> Do we need to setup the `e32, len=t0` for next IV? >> I think we only need 128bit IV (with VL=4). >> >>> + aes_decrypt v20, \keylen // Decrypt the blocks >>> + vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks >>> + vse32.v v20, (OUTP) // Store plaintext blocks >>> + vmv.v.v v16, v24 // Next "IV" is last ciphertext block >> >> Same VL issue here. > > It's true that the vslidedown.vx and vmv.v.v only need vl=4. But it also works > fine with vl unchanged. It just results in some extra data being moved in the > registers. My hypothesis is that this is going to be faster than having the > three extra instructions per loop iteration to change the vl to 4 twice. > > I still have no real hardware to test on, so I have no quantitative data. All I > can do is go with my instinct which is that the shorter version will be better. > > If you have access to a real CPU that supports the RISC-V vector crypto > extensions, I'd be interested in the performance you get from each variant. > (Of course, different RISC-V CPU implementations may have quite different > performance characteristics, so that still won't be definitive.) Hi Eric, Thank you. I think the extra vl doesn't affect performance significantly. The main tasks are still the aes body. The original implementation is enough right now. > In general, this level of micro-optimization probably needs to be wait until > there are a variety of CPUs to test on. We know that parallelizing the > algorithms is helpful, so we should do that, as this patch does. But the > effects of small variations in the instruction sequences are currently unclear. > > - Eric
On Sat, 10 Feb 2024 10:12:40 PST (-0800), ebiggers@kernel.org wrote: > On Sat, Feb 10, 2024 at 11:25:27PM +0800, Jerry Shih wrote: >> > .macro aes_cbc_decrypt keylen >> > + srli LEN, LEN, 2 // Convert LEN from bytes to words >> > vle32.v v16, (IVP) // Load IV >> > 1: >> > - vle32.v v17, (INP) // Load ciphertext block >> > - vmv.v.v v18, v17 // Save ciphertext block >> > - aes_decrypt v17, \keylen // Decrypt >> > - vxor.vv v17, v17, v16 // XOR with IV or prev ciphertext block >> > - vse32.v v17, (OUTP) // Store plaintext block >> > - vmv.v.v v16, v18 // Next "IV" is prev ciphertext block >> > - addi INP, INP, 16 >> > - addi OUTP, OUTP, 16 >> > - addi LEN, LEN, -16 >> > + vsetvli t0, LEN, e32, m4, ta, ma >> > + vle32.v v20, (INP) // Load ciphertext blocks >> > + vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks >> > + addi t1, t0, -4 >> > + vslidedown.vx v24, v20, t1 // Save last ciphertext block >> >> Do we need to setup the `e32, len=t0` for next IV? >> I think we only need 128bit IV (with VL=4). >> >> > + aes_decrypt v20, \keylen // Decrypt the blocks >> > + vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks >> > + vse32.v v20, (OUTP) // Store plaintext blocks >> > + vmv.v.v v16, v24 // Next "IV" is last ciphertext block >> >> Same VL issue here. > > It's true that the vslidedown.vx and vmv.v.v only need vl=4. But it also works > fine with vl unchanged. It just results in some extra data being moved in the > registers. My hypothesis is that this is going to be faster than having the > three extra instructions per loop iteration to change the vl to 4 twice. > > I still have no real hardware to test on, so I have no quantitative data. All I > can do is go with my instinct which is that the shorter version will be better. > > If you have access to a real CPU that supports the RISC-V vector crypto > extensions, I'd be interested in the performance you get from each variant. > (Of course, different RISC-V CPU implementations may have quite different > performance characteristics, so that still won't be definitive.) We're stacking up a lot of stuff with HW-dependent performance questions, I think it's fine to just take what's reasonably simple for now. If we try to speculate about what future hardware might do we're just going to go crazy with possibilities, IMO we're way better off just optimizing as things show up. > Here is the alternative variant given as a diff from this patch: > > diff --git a/arch/riscv/crypto/aes-riscv64-zvkned.S b/arch/riscv/crypto/aes-riscv64-zvkned.S > index 43541aad6386c..ef380771f606a 100644 > --- a/arch/riscv/crypto/aes-riscv64-zvkned.S > +++ b/arch/riscv/crypto/aes-riscv64-zvkned.S > @@ -146,10 +146,13 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) > vle32.v v20, (INP) // Load ciphertext blocks > vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks > addi t1, t0, -4 > + vsetivli zero, 4, e32, m4, ta, ma > vslidedown.vx v24, v20, t1 // Save last ciphertext block > + vsetvli t0, LEN, e32, m4, ta, ma > aes_decrypt v20, \keylen // Decrypt the blocks > vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks > vse32.v v20, (OUTP) // Store plaintext blocks > + vsetivli zero, 4, e32, m4, ta, ma > vmv.v.v v16, v24 // Next "IV" is last ciphertext block > slli t1, t0, 2 // Words to bytes > add INP, INP, t1 > @@ -157,7 +160,6 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) > sub LEN, LEN, t0 > bnez LEN, 1b > > - vsetivli zero, 4, e32, m1, ta, ma > vse32.v v16, (IVP) // Store next IV > ret > .endm > > A third variant would be to just replace vmv.v.v with vmv1r.v. > > In general, this level of micro-optimization probably needs to be wait until > there are a variety of CPUs to test on. We know that parallelizing the > algorithms is helpful, so we should do that, as this patch does. But the > effects of small variations in the instruction sequences are currently unclear. Ya, I agree. So I'm fine with this, it's a base and we can always improve it when there's something concrete to run on. > - Eric
Hello: This patch was applied to riscv/linux.git (for-next) by Palmer Dabbelt <palmer@rivosinc.com>: On Wed, 7 Feb 2024 22:08:51 -0800 you wrote: > From: Eric Biggers <ebiggers@google.com> > > Since CBC decryption is parallelizable, make the RISC-V implementation > of AES-CBC decryption process multiple blocks at a time, instead of > processing the blocks one by one. This should improve performance. > > Signed-off-by: Eric Biggers <ebiggers@google.com> > > [...] Here is the summary with links: - [riscv/for-next] crypto: riscv - parallelize AES-CBC decryption https://git.kernel.org/riscv/c/da215b089b5d You are awesome, thank you!
diff --git a/arch/riscv/crypto/aes-riscv64-zvkned.S b/arch/riscv/crypto/aes-riscv64-zvkned.S index 78d4e1186c074..43541aad6386c 100644 --- a/arch/riscv/crypto/aes-riscv64-zvkned.S +++ b/arch/riscv/crypto/aes-riscv64-zvkned.S @@ -132,33 +132,39 @@ SYM_FUNC_END(aes_ecb_decrypt_zvkned) addi INP, INP, 16 addi OUTP, OUTP, 16 addi LEN, LEN, -16 bnez LEN, 1b vse32.v v16, (IVP) // Store next IV ret .endm .macro aes_cbc_decrypt keylen + srli LEN, LEN, 2 // Convert LEN from bytes to words vle32.v v16, (IVP) // Load IV 1: - vle32.v v17, (INP) // Load ciphertext block - vmv.v.v v18, v17 // Save ciphertext block - aes_decrypt v17, \keylen // Decrypt - vxor.vv v17, v17, v16 // XOR with IV or prev ciphertext block - vse32.v v17, (OUTP) // Store plaintext block - vmv.v.v v16, v18 // Next "IV" is prev ciphertext block - addi INP, INP, 16 - addi OUTP, OUTP, 16 - addi LEN, LEN, -16 + vsetvli t0, LEN, e32, m4, ta, ma + vle32.v v20, (INP) // Load ciphertext blocks + vslideup.vi v16, v20, 4 // Setup prev ciphertext blocks + addi t1, t0, -4 + vslidedown.vx v24, v20, t1 // Save last ciphertext block + aes_decrypt v20, \keylen // Decrypt the blocks + vxor.vv v20, v20, v16 // XOR with prev ciphertext blocks + vse32.v v20, (OUTP) // Store plaintext blocks + vmv.v.v v16, v24 // Next "IV" is last ciphertext block + slli t1, t0, 2 // Words to bytes + add INP, INP, t1 + add OUTP, OUTP, t1 + sub LEN, LEN, t0 bnez LEN, 1b + vsetivli zero, 4, e32, m1, ta, ma vse32.v v16, (IVP) // Store next IV ret .endm // void aes_cbc_encrypt_zvkned(const struct crypto_aes_ctx *key, // const u8 *in, u8 *out, size_t len, u8 iv[16]); // // |len| must be nonzero and a multiple of 16 (AES_BLOCK_SIZE). SYM_FUNC_START(aes_cbc_encrypt_zvkned) aes_begin KEYP, 128f, 192f