[PULL 17/33] target/s390x: Minimal protected key AES XTS support for cpacf pcc instruction

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

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

Support CPACF pcc subfunctions PCC-Compute-XTS-Parameter-Encrypted-AES-128
and PCC-Compute-XTS-Parameter-Encrypted-AES-128 but only for the special
case block sequential number is 0. However, this covers the s390 PAES XTS
implementation in the Linux kernel.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Tested-by: Holger Dengler <dengler@linux.ibm.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20260824083204.40877-18-freude@linux.ibm.com
Signed-off-by: Eric Farman <farman@linux.ibm.com>
---
 target/s390x/gen-features.c      |  2 +
 target/s390x/tcg/cpacf.h         |  2 +
 target/s390x/tcg/cpacf_aes.c     | 64 ++++++++++++++++++++++++++++++++
 target/s390x/tcg/crypto_helper.c |  4 ++
 4 files changed, 72 insertions(+)

diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 01149a04c5..1ed0d4efeb 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -951,6 +951,8 @@ static uint16_t qemu_MAX[] = {
     S390_FEAT_KMCTR_EAES_256,
     S390_FEAT_PCC_XTS_AES_128,
     S390_FEAT_PCC_XTS_AES_256,
+    S390_FEAT_PCC_XTS_EAES_128,
+    S390_FEAT_PCC_XTS_EAES_256,
     S390_FEAT_PCKMO_AES_128,
     S390_FEAT_PCKMO_AES_192,
     S390_FEAT_PCKMO_AES_256,
diff --git a/target/s390x/tcg/cpacf.h b/target/s390x/tcg/cpacf.h
index 15fd860e3a..f0c2e7fb6c 100644
--- a/target/s390x/tcg/cpacf.h
+++ b/target/s390x/tcg/cpacf.h
@@ -53,5 +53,7 @@ int cpacf_paes_ctr(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
                    uint64_t *src_ptr_reg, uint64_t *src_len_reg,
                    uint64_t *ctr_ptr_reg, uint32_t type,
                    uint8_t fc, uint8_t mod);
+int cpacf_paes_pcc(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
+                   uint64_t param_addr, uint8_t fc);
 
 #endif /* S390X_CPACF_H */
diff --git a/target/s390x/tcg/cpacf_aes.c b/target/s390x/tcg/cpacf_aes.c
index 52f8644468..dbbe5bda64 100644
--- a/target/s390x/tcg/cpacf_aes.c
+++ b/target/s390x/tcg/cpacf_aes.c
@@ -815,3 +815,67 @@ int cpacf_paes_ctr(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
 
     return !len ? 0 : 3;
 }
+
+int cpacf_paes_pcc(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
+                   uint64_t param_addr, uint8_t fc)
+{
+    uint8_t key[32], wkvp[32], tweak[AES_BLOCK_SIZE], buf[AES_BLOCK_SIZE];
+    int keysize, i;
+    AES_KEY exkey;
+
+    switch (fc) {
+    case CPACF_PCC_XTS_PAES_128:
+        keysize = 16;
+        break;
+    case CPACF_PCC_XTS_PAES_256:
+        keysize = 32;
+        break;
+    default:
+        g_assert_not_reached();
+    }
+
+    /* fetch and check wkvp from param block */
+    read_guest_wrap_u8(env, mmu_idx, ra,
+                       param_addr + keysize, wkvp, sizeof(wkvp));
+    if (memcmp(wkvp, protkey_wkvp, sizeof(wkvp))) {
+        /* wkvp mismatch -> return with cc 1 */
+        return 1;
+    }
+
+    /* fetch block sequence nr from param block into buf */
+    read_guest_wrap_u8(env, mmu_idx, ra,
+                       param_addr + keysize + sizeof(wkvp) + AES_BLOCK_SIZE,
+                       buf, AES_BLOCK_SIZE);
+
+    /* is the block sequence nr 0 ? */
+    for (i = 0; i < AES_BLOCK_SIZE && !buf[i]; i++) {
+        ;
+    }
+    if (i < AES_BLOCK_SIZE) {
+        /* no, sorry handling of non zero block sequence is not implemented */
+        tcg_s390_program_interrupt(env, PGM_SPECIFICATION, ra);
+    }
+
+    /* fetch protected key from param block */
+    read_guest_wrap_u8(env, mmu_idx, ra, param_addr, key, keysize);
+    /* decrypt the protected key */
+    decrypt_protkey(key, keysize);
+
+    /* fetch tweak from param block into tweak */
+    read_guest_wrap_u8(env, mmu_idx, ra,
+                       param_addr + keysize + sizeof(wkvp),
+                       tweak, AES_BLOCK_SIZE);
+
+    /* expand key */
+    AES_set_encrypt_key(key, keysize * 8, &exkey);
+
+    /* encrypt tweak */
+    AES_encrypt(tweak, buf, &exkey);
+
+    /* store encrypted tweak into xts parameter field of the param block */
+    write_guest_wrap_u8(env, mmu_idx, ra,
+                        param_addr + keysize + sizeof(wkvp) + 3 * AES_BLOCK_SIZE,
+                        buf, AES_BLOCK_SIZE);
+
+    return 0;
+}
diff --git a/target/s390x/tcg/crypto_helper.c b/target/s390x/tcg/crypto_helper.c
index 44fb7611cd..886f9c72d6 100644
--- a/target/s390x/tcg/crypto_helper.c
+++ b/target/s390x/tcg/crypto_helper.c
@@ -219,6 +219,10 @@ static int cpacf_pcc(CPUS390XState *env, const int mmu_idx, uintptr_t ra,
     case CPACF_PCC_XTS_AES_256:
         rc = cpacf_aes_pcc(env, mmu_idx, ra, env->regs[1], fc);
         break;
+    case CPACF_PCC_XTS_PAES_128:
+    case CPACF_PCC_XTS_PAES_256:
+        rc = cpacf_paes_pcc(env, mmu_idx, ra, env->regs[1], fc);
+        break;
     default:
         tcg_s390_program_interrupt(env, PGM_SPECIFICATION, ra);
     }
-- 
2.55.0