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Sun, 22 Jun 2025 12:23:55 GMT Received: from smtpav04.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 35A2558056; Sun, 22 Jun 2025 12:23:55 +0000 (GMT) Received: from smtpav04.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8B7C158052; Sun, 22 Jun 2025 12:23:54 +0000 (GMT) Received: from li-43857255-d5e6-4659-90f1-fc5cee4750ad.ibm.com (unknown [9.61.92.25]) by smtpav04.dal12v.mail.ibm.com (Postfix) with ESMTP; Sun, 22 Jun 2025 12:23:54 +0000 (GMT) Message-ID: <82acbfc071095da7cc153ec8f2fbdca6316c82bd.camel@linux.ibm.com> Subject: Re: [PATCH v4 2/2] tpm: tpm_crb_ffa: try to probe tpm_crb_ffa when it's built-in From: Mimi Zohar To: Yeoreum Yun , jarkko@kernel.org, sudeep.holla@arm.com, peterhuewe@gmx.de, jgg@ziepe.ca, stuart.yoder@arm.com Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org In-Reply-To: <20250618102302.2379029-3-yeoreum.yun@arm.com> References: <20250618102302.2379029-1-yeoreum.yun@arm.com> <20250618102302.2379029-3-yeoreum.yun@arm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Sun, 22 Jun 2025 08:23:54 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNjIyMDA3NiBTYWx0ZWRfX8TnzgF/9CxZc 4VXGQ3mJdEYXHR0EbygG6IMVeHVAyZhhAipmbftjbNOQqK/MItklH8swl7LDw4XOzFgtpvD29vX bbDLGr2ZrCUuJ0JlgqrBOhDAd6jmHJKrELYolZc6yrESr71T3vuE/GZrsHG51/gnIZIgARFvZNc 6xteH/mlCins3SZkgmPsG2QDLbL0f61d6hYacBlMjQZfoNOV8mNZStDLWPhkQTTr6ZH+MMCLiIz pxukxj1fTADDUYsHKfWDlKEPe+jqWi5wr7axE6AmJRU6+49Hf0TNpc9pSHJukT7WGZF1gnXJveR G0DLlousKZFm8Odg18s9hdo/Og7FDsfHn2mqkztuNQeTvnky/JxWKseWhVMyFFEBtOr67ewhQ38 i1sOMYKHiH9tqHLGwOgMUwDV241YMuuVaJbHoxTkDJLrljQWzJphlf98n5yYG5zAPWjwyhF+ X-Proofpoint-GUID: FtRl5aB2iy992nm6u0N62rVbDKcdzle8 X-Proofpoint-ORIG-GUID: BWgFVlbVuMyff2u4xjoRrzmut-6DCtPI X-Authority-Analysis: v=2.4 cv=combk04i c=1 sm=1 tr=0 ts=6857f5dd cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=6IFa9wvqVegA:10 a=7CQSdrXTAAAA:8 a=VnNF1IyMAAAA:8 a=dY7dXPFekxP_jGxdfwkA:9 a=QEXdDO2ut3YA:10 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-06-22_04,2025-06-20_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 spamscore=0 adultscore=0 mlxlogscore=999 clxscore=1015 impostorscore=0 suspectscore=0 mlxscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2506220076 On Wed, 2025-06-18 at 11:23 +0100, Yeoreum Yun wrote: > To generate the boot_aggregate log in the IMA subsystem using TPM PCR val= ues, > the TPM driver must be built as built-in and must be probed before > the IMA subsystem is initialized. >=20 > However, when the TPM device operates over the FF-A protocol using the CR= B interface, > probing fails and returns -EPROBE_DEFER > if the tpm_crb_ffa device =E2=80=94 an FF-A device that provides > the communication interface to the tpm_crb driver =E2=80=94 has not yet b= een probed. >=20 > This issue occurs because both crb_acpi_driver_init() and > tpm_crb_ffa_driver_init() are registered with device_initcall. > As a result, crb_acpi_driver_init() may be invoked before > tpm_crb_ffa_driver_init(), which is responsible for probing the tpm_crb_f= fa device. >=20 > When this happens, IMA fails to detect the TPM device and > logs the following message: >=20 > | ima: No TPM chip found, activating TPM-bypass! >=20 > Consequently, it cannot generate the boot_aggregate log with > the PCR values provided by the TPM. >=20 > To resolve this issue, the tpm_crb_ffa_init() function explicitly attempt= s to > probe the tpm_crb_ffa by register tpm_crb_ffa driver so that > when tpm_crb_ffa device is created before tpm_crb_ffa_init(), > probe the tpm_crb_ffa device in tpm_crb_ffa_init() to finish probe the > TPM device completely. >=20 > This ensures that the TPM device using CRB over FF-A > can be successfully probed, even if crb_acpi_driver_init() is called firs= t. >=20 > Signed-off-by: Yeoreum Yun > --- > drivers/char/tpm/tpm_crb_ffa.c | 19 ++++++++++++++++--- > 1 file changed, 16 insertions(+), 3 deletions(-) >=20 > diff --git a/drivers/char/tpm/tpm_crb_ffa.c b/drivers/char/tpm/tpm_crb_ff= a.c > index 4ead61f01299..462fcf610020 100644 > --- a/drivers/char/tpm/tpm_crb_ffa.c > +++ b/drivers/char/tpm/tpm_crb_ffa.c > @@ -115,6 +115,7 @@ struct tpm_crb_ffa { > }; > =20 > static struct tpm_crb_ffa *tpm_crb_ffa; > +static struct ffa_driver tpm_crb_ffa_driver; > =20 > static int tpm_crb_ffa_to_linux_errno(int errno) > { > @@ -168,13 +169,23 @@ static int tpm_crb_ffa_to_linux_errno(int errno) > */ > int tpm_crb_ffa_init(void) > { > + int ret =3D 0; > + > + if (!IS_MODULE(CONFIG_TCG_ARM_CRB_FFA)) { > + ret =3D ffa_register(&tpm_crb_ffa_driver); > + if (ret) { > + tpm_crb_ffa =3D ERR_PTR(-ENODEV); > + return ret; > + } > + } > + > if (!tpm_crb_ffa) > - return -ENOENT; > + ret =3D -ENOENT; > =20 > if (IS_ERR_VALUE(tpm_crb_ffa)) > - return -ENODEV; > + ret =3D -ENODEV; > =20 > - return 0; > + return ret; > } > EXPORT_SYMBOL_GPL(tpm_crb_ffa_init); > =20 > @@ -369,7 +380,9 @@ static struct ffa_driver tpm_crb_ffa_driver =3D { > .id_table =3D tpm_crb_ffa_device_id, > }; > =20 > +#ifdef MODULE > module_ffa_driver(tpm_crb_ffa_driver); > +#endif > =20 > MODULE_AUTHOR("Arm"); > MODULE_DESCRIPTION("TPM CRB FFA driver"); LGTM. Using ifndef/ifdef MODULE is similar to how module_init() works for = both builtin and loadable kernel modules. Except module_init() is on the device_initcall(). Reviewed-by: Mimi Zohar