[PULL 12/33] target/s390x: Support AES XTS for cpacf km instruction

[Eric Farman <farman@linux.ibm.com>]

From: Harald Freudenberger <freude@linux.ibm.com>

Support the subfunctions XTS-AES-128 and XTS-AES-256
for the cpacf km instruction.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Tested-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260824083204.40877-13-freude@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 target/s390x/gen-features.c      |  2 +
 target/s390x/tcg/cpacf.h         |  4 ++
 target/s390x/tcg/cpacf_aes.c     | 93 ++++++++++++++++++++++++++++++++
 target/s390x/tcg/crypto_helper.c |  6 +++
 4 files changed, 105 insertions(+)

diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 34e2be3af1..ad99f9ff85 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -932,6 +932,8 @@ static uint16_t qemu_MAX[] = {
     S390_FEAT_KM_AES_128,
     S390_FEAT_KM_AES_192,
     S390_FEAT_KM_AES_256,
+    S390_FEAT_KM_XTS_AES_128,
+    S390_FEAT_KM_XTS_AES_256,
     S390_FEAT_KMC_AES_128,
     S390_FEAT_KMC_AES_192,
     S390_FEAT_KMC_AES_256,
diff --git a/target/s390x/tcg/cpacf.h b/target/s390x/tcg/cpacf.h
index 4a20aeacde..5013e19907 100644
--- a/target/s390x/tcg/cpacf.h
+++ b/target/s390x/tcg/cpacf.h
@@ -34,5 +34,9 @@ int cpacf_aes_ctr(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
                   uint8_t fc, uint8_t mod);
 int cpacf_aes_pcc(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
                   uint64_t param_addr, uint8_t fc);
+int cpacf_aes_xts(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
+                  uint64_t param_addr, uint64_t *dst_ptr_reg,
+                  uint64_t *src_ptr_reg, uint64_t *src_len_reg,
+                  uint32_t type, uint8_t fc, uint8_t mod);
 
 #endif /* S390X_CPACF_H */
diff --git a/target/s390x/tcg/cpacf_aes.c b/target/s390x/tcg/cpacf_aes.c
index 6c7b959bd9..f705bd6677 100644
--- a/target/s390x/tcg/cpacf_aes.c
+++ b/target/s390x/tcg/cpacf_aes.c
@@ -361,3 +361,96 @@ int cpacf_aes_pcc(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
 
     return 0;
 }
+
+int cpacf_aes_xts(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
+                  uint64_t param_addr, uint64_t *dst_ptr_reg,
+                  uint64_t *src_ptr_reg, uint64_t *src_len_reg,
+                  uint32_t type, uint8_t fc, uint8_t mod)
+{
+    enum { MAX_BLOCKS_PER_RUN = 8192 / AES_BLOCK_SIZE };
+    uint8_t in[AES_BLOCK_SIZE], out[AES_BLOCK_SIZE];
+    uint64_t len = *src_len_reg, done = 0;
+    uint8_t key[32], tweak[AES_BLOCK_SIZE];
+    int i, keysize, addr_reg_size;
+    AES_KEY exkey;
+
+    g_assert(type == S390_FEAT_TYPE_KM);
+
+    switch (fc) {
+    case CPACF_KM_XTS_128:
+        keysize = 16;
+        break;
+    case CPACF_KM_XTS_256:
+        keysize = 32;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    /* check addressing mode, raise exception if not supported here */
+    addr_reg_size = get_address_bitsize(env);
+    switch (addr_reg_size) {
+    case 64:
+        break;
+    case 32:
+        len = (uint32_t)len;
+        break;
+    default:
+        tcg_s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+    }
+
+    /* early bail out if length is zero */
+    if (!len) {
+        return 0;
+    }
+
+    /* length has to be properly aligned. */
+    if (!QEMU_IS_ALIGNED(len, AES_BLOCK_SIZE)) {
+        tcg_s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+    }
+
+    /* fetch key from param block */
+    read_guest_wrap_u8(env, mmu_idx, ra, param_addr, key, keysize);
+
+    /* expand key */
+    if (mod) {
+        AES_set_decrypt_key(key, keysize * 8, &exkey);
+    } else {
+        AES_set_encrypt_key(key, keysize * 8, &exkey);
+    }
+
+    /* fetch tweak from param block */
+    read_guest_wrap_u8(env, mmu_idx, ra,
+                       param_addr + keysize, tweak, AES_BLOCK_SIZE);
+
+    /* process up to MAX_BLOCKS_PER_RUN aes blocks */
+    for (i = 0; i < MAX_BLOCKS_PER_RUN && len >= AES_BLOCK_SIZE; i++) {
+        /* fetch one AES block into in  */
+        aes_read_block(env, mmu_idx, ra, *src_ptr_reg + done, in);
+        if (mod) {
+            /* decrypt in => out */
+            AES_xts_decrypt(in, out, tweak, &exkey);
+        } else {
+            /* encrypt in => out */
+            AES_xts_encrypt(in, out, tweak, &exkey);
+        }
+        /* prep tweak for next round */
+        AES_xts_prep_next_tweak(tweak);
+        /* write out this processed block from out */
+        aes_write_block(env, mmu_idx, ra, *dst_ptr_reg + done, out);
+        len -= AES_BLOCK_SIZE;
+        done += AES_BLOCK_SIZE;
+    }
+
+    /* update tweak in param block */
+    write_guest_wrap_u8(env, mmu_idx, ra,
+                        param_addr + keysize, tweak, AES_BLOCK_SIZE);
+
+    *src_ptr_reg = deposit64(*src_ptr_reg, 0, addr_reg_size,
+                             *src_ptr_reg + done);
+    *dst_ptr_reg = deposit64(*dst_ptr_reg, 0, addr_reg_size,
+                             *dst_ptr_reg + done);
+    *src_len_reg -= done;
+
+    return !len ? 0 : 3;
+}
diff --git a/target/s390x/tcg/crypto_helper.c b/target/s390x/tcg/crypto_helper.c
index c829d16f74..2bd39f8978 100644
--- a/target/s390x/tcg/crypto_helper.c
+++ b/target/s390x/tcg/crypto_helper.c
@@ -112,6 +112,12 @@ static int cpacf_km(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
                            &env->regs[r1], &env->regs[r2], &env->regs[r2 + 1],
                            S390_FEAT_TYPE_KM, fc, mod);
         break;
+    case CPACF_KM_XTS_128:
+    case CPACF_KM_XTS_256:
+        rc = cpacf_aes_xts(env, mmu_idx, ra, env->regs[1],
+                           &env->regs[r1], &env->regs[r2], &env->regs[r2 + 1],
+                           S390_FEAT_TYPE_KM, fc, mod);
+        break;
     default:
         tcg_s390_program_interrupt(env, PGM_SPECIFICATION, ra);
     }
-- 
2.55.0