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Tue, 7 Jul 2026 16:18:16 +0000 (GMT) From: Harald Freudenberger To: richard.henderson@linaro.org, iii@linux.ibm.com, david@kernel.org, thuth@redhat.com, berrange@redhat.com Cc: qemu-s390x@nongnu.org, qemu-devel@nongnu.org, linux-s390@vger.kernel.org, dengler@linux.ibm.com, borntraeger@linux.ibm.com, fcallies@linux.ibm.com, cohuck@redhat.com Subject: [PATCH v11 17/21] docs/s390: Document CPACF instructions support Date: Tue, 7 Jul 2026 18:18:04 +0200 Message-ID: <20260707161815.40919-18-freude@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260707161815.40919-1-freude@linux.ibm.com> References: <20260707161815.40919-1-freude@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: CcCif5iwI51WF4FGcDe15X6mYxNUXdTI X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzA3MDE2MCBTYWx0ZWRfX6/QLA0+2Fg7X Vctan9kSlwzjsbyeZzAzlDo09x8Y0vAeQBq9xd0EgSSjC0Awcfs3jzUXDdJoLRk8D7gkobU7nVq 518+UXnkcLGmaQtzHRLZvlPaHmFJA2pR/Z2GR2IJujeTxqJdH31nJwfoaVpt3tvq6W6iFImMaOV OttM7zSlTgQWrvEcnqK/zZyE4SGaeRW9a0axbQd+RatiZiVomniSl9j3O9P3nZuGXLfKFuyr109 5vQ56BRqTlTqr1tJxN/c4/caJd7FCDWH/RaqjbmCBgGZ8FVcZVnMVvvIp04vZT67FFDy92ViqEA qzJ3icm3IlLIhbXmC4HHJQhp69YBNX0Ge0AVMYxaABKeKnN4wddbMg31odpaLO9LQ3/qC5CJk8y gTxyJ3H2ap8cHkQScSma2XvxwWfywdsB8iZ54BujFPXlBkgyhsBgDRQF5JuQXwFdfnNaWDr1Tzz csFszO0ZRyWwxgWCkQQ== X-Proofpoint-ORIG-GUID: CcCif5iwI51WF4FGcDe15X6mYxNUXdTI X-Authority-Analysis: v=2.4 cv=FqQ1OWrq c=1 sm=1 tr=0 ts=6a4d26ce cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=IlYB4z8HrC9mJJy16gAA:9 a=5wi_FRADO1KgGG3s:21 a=O8hF6Hzn-FEA:10 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzA3MDE2MCBTYWx0ZWRfXzcNXOLxuMcIy aUrXShsK3KVG7jqLI5wJZ8rTHHcwaLx70KvlJCae44iiiP9XtMehdJjJwX+yOhrnMmQJZDeBKLX iJaegnsuM4KHWQD6lr00gFxXiEttIBE= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-07_04,2026-07-06_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 clxscore=1015 malwarescore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 suspectscore=0 spamscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607070160 Add a first document covering the Qemu s390 CPACF instructions and functions supported. Signed-off-by: Harald Freudenberger Reviewed-by: Finn Callies --- docs/system/s390x/cpacf.rst | 146 +++++++++++++++++++++++++++++++++++ docs/system/target-s390x.rst | 1 + 2 files changed, 147 insertions(+) create mode 100644 docs/system/s390x/cpacf.rst diff --git a/docs/system/s390x/cpacf.rst b/docs/system/s390x/cpacf.rst new file mode 100644 index 0000000000..4b77146a98 --- /dev/null +++ b/docs/system/s390x/cpacf.rst @@ -0,0 +1,146 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +CPACF Support +============= + +CPACF +----- + +CP Assist for Cryptographic Function (CPACF) is a hardware-integrated +coprocessor feature built into every processor core of IBM Z and +LinuxONE mainframes (s390x architecture). It provides high-speed, +hardware-accelerated encryption and hashing directly on the CPU. + +CPACF provides a set of z/Architecture instructions (known as Message +Security Assist or MSA) that execute cryptographic operations +synchronously with the main processor. + +- Symmetric Encryption: Support for AES (128, 192, 256-bit), DES, and + Triple-DES (TDES). +- Hashing: Acceleration for SHA-1, SHA-2 (up to SHA-512), SHA-3 and + SHAKE. +- Random Number Generation: Pseudo Random Number Generator (PRNG) and + a hardware-based True Random Number Generator (TRNG). +- Asymmetric Support: Elliptic Curve Cryptography (ECC) primitives + P-256, P-384, P-521, Montgomery/Edwards curves (e.g., Ed25519). + +Documentation about CPACF instructions is publicly available and +can be found in the "z/Architecture Principles of Operation" +accessible at the IBM documentation hub https://www.ibm.com/docs/en. +For example the latest version as a pdf is available here: +https://www.ibm.com/support/pages/zvm/library/other/22783214.pdf + + +CPACF instructions +------------------ + +Here is a list of implemented CPACF instructions and the supported +functions for each instruction: + +KDSA (COMPUTE DIGITAL SIGNATURE AUTHENTICATION) +- Function code 0x00 - Function Query + +KIMD (COMPUTE INTERMEDIATE MESSAGE DIGEST) +- Function code 0x00 - Function Query +- Function code 0x02 - CPACF_KIMD_SHA_256 +- Function code 0x03 - CPACF_KIMD_SHA_512 + +KLMD (COMPUTE LAST MESSAGE DIGEST) +- Function code 0x00 - Function Query +- Function code 0x02 - CPACF_KLMD_SHA_256 +- Function code 0x03 - CPACF_KLMD_SHA_512 + +KM (CIPHER MESSAGE) +- Function code 0x00 - Function Query +- Function code 0x12 - CPACF_KM_AES_128 +- Function code 0x13 - CPACF_KM_AES_192 +- Function code 0x14 - CPACF_KM_AES_256 +- Function code 0x1a - CPACF_KM_PAES_128 +- Function code 0x1b - CPACF_KM_PAES_192 +- Function code 0x1c - CPACF_KM_PAES_256 +- Function code 0x32 - CPACF_KM_XTS_128 +- Function code 0x34 - CPACF_KM_XTS_256 +- Function code 0x3a - CPACF_KM_PXTS_128 +- Function code 0x3c - CPACF_KM_PXTS_256 + +KMAC (COMPUTE MESSAGE AUTHENTICATION CODE) +- Function code 0x00 - Function Query + +KMC (CIPHER MESSAGE WITH CHAINING) +- Function code 0x00 - Function Query +- Function code 0x12 - CPACF_KMC_AES_128 +- Function code 0x13 - CPACF_KMC_AES_192 +- Function code 0x14 - CPACF_KMC_AES_256 +- Function code 0x1a - CPACF_KMC_PAES_128 +- Function code 0x1b - CPACF_KMC_PAES_192 +- Function code 0x1c - CPACF_KMC_PAES_256 + +KMCTR (CIPHER MESSAGE WITH COUNTER) +- Function code 0x00 - Function Query +- Function code 0x12 - CPACF_KMCTR_AES_128 +- Function code 0x13 - CPACF_KMCTR_AES_192 +- Function code 0x14 - CPACF_KMCTR_AES_256 +- Function code 0x1a - CPACF_KMCTR_PAES_128 +- Function code 0x1b - CPACF_KMCTR_PAES_192 +- Function code 0x1c - CPACF_KMCTR_PAES_256 + +KMF (CIPHER MESSAGE WITH CIPHER FEEDBACK) +- not supported + +KMO (CIPHER MESSAGE WITH OUTPUT FEEDBACK) +- not supported + +PCC (PERFORM CRYPTOGRAPHIC COMPUTATION) +- Function code 0x00 - Function Query +- Function code 0x32 - compute XTS param AES-128 +- Function code 0x34 - compute XTS param AES-256 +- Function code 0x3a - compute XTS param Encrypted AES-128 +- Function code 0x3c - compute XTS param Encrypted AES-256 + +PCKMO (PERFORM CRYPTOGRAPHIC KEY MANAGEMENT OPERATION) +- Function code 0x00 - Function Query +- Function code 0x12 - CPACF_PCKMO_ENC_AES_128_KEY +- Function code 0x13 - CPACF_PCKMO_ENC_AES_192_KEY +- Function code 0x14 - CPACF_PCKMO_ENC_AES_256_KEY + +PRNO (PERFORM RANDOM NUMBER OPERATION) +- Function code 0x00 - Function Query +- Function code 0x72 - CPACF_PRNO_TRNG + +Note that the use of a not supported CPACF instruction (KMF and KMO) +or invocation of a not listed function will result in a Specification +Exception. + +Not listed CPACF instructions (KMA, KMF, KMO) cause an Operation +Exception when used. Not listed functions cause a Specification +Exception when called. If only the query function is listed (KDSA), +then the query function will return a function status word with all +but the query function bit set to 0. + + +Protected key support +--------------------- + +The qemu version for protected key support is only a fake provided +here for developing and testing purpose: + +- The protected key is _derived_ from the clear key by xoring the + fixed pattern 0xAAAA... onto the key value. +- The AES Wrapping Key Verification Pattern is a fixed value of 32 + bytes 0xFACEFACE... + +The PCKMO instruction implementation does exactly this - _derive_ a +_protected_ key from the clear key given by xor 0xAAAA... and writing +the fixed value for the WKVP of 0xFACEFACE into the blob. +The other subfunctions of the CPACF instructions dealing with +protected key treat the protected key blob by first checking for the +WKVP (against the fixed value of 0xFACEFACE...) and second +_decrypting_ the key value by xoring 0xAAAA... and then execute the +clear key operation with the decrypted key value. +This is suitable for testing purpose but such keys are not for real +production load and would open up a huge security breach! + +For more details about protected keys see the "z/Architecture +Principles of Operation" document chapter "General Instructions" +sub-chapter "Protection of Cryptographic Keys" and again the +implementation here does NOT implement what is explained there. diff --git a/docs/system/target-s390x.rst b/docs/system/target-s390x.rst index 94c981e732..49159826eb 100644 --- a/docs/system/target-s390x.rst +++ b/docs/system/target-s390x.rst @@ -35,3 +35,4 @@ Architectural features s390x/bootdevices s390x/protvirt s390x/cpu-topology + s390x/cpacf -- 2.43.0