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Shutemov" , Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: [RFC PATCH 04/20] x86/virt/tdx: Introduce a "tdx" subsystem and "tsm" device Date: Fri, 23 May 2025 02:52:27 -0700 Message-ID: <20250523095322.88774-5-chao.gao@intel.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250523095322.88774-1-chao.gao@intel.com> References: <20250523095322.88774-1-chao.gao@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" TDX depends on a platform firmware module that is invoked via instructions similar to vmenter (i.e. enter into a new privileged "root-mode" context to manage private memory and private device mechanisms). It is a software construct that depends on the CPU vmxon state to enable invocation of TDX-module ABIs. Unlike other Trusted Execution Environment (TEE) platform implementations that employ a firmware module running on a PCI device with an MMIO mailbox for communication, TDX has no hardware device to point to as the "TSM". The "/sys/devices/virtual" hierarchy is intended for "software constructs which need sysfs interface", which aligns with what TDX needs. The new tdx_subsys will export global attributes populated by the TDX-module "sysinfo". A tdx_tsm device is published on this bus to enable a typical driver model for the low level "TEE Security Manager" (TSM) flows that talk TDISP to capable PCIe devices. For now, this is only the base tdx_subsys and tdx_tsm device registration with attribute definition and TSM driver to follow later. Co-developed-by: Dan Williams Signed-off-by: Dan Williams Signed-off-by: Chao Gao Tested-by: Farrah Chen --- arch/x86/virt/vmx/tdx/tdx.c | 75 +++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index b586329dd87d..9719df2f2634 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -28,6 +28,8 @@ #include #include #include +#include +#include #include #include #include @@ -1080,6 +1082,77 @@ static int init_tdmrs(struct tdmr_info_list *tdmr_li= st) return 0; } =20 +static const struct bus_type tdx_subsys =3D { + .name =3D "tdx", +}; + +struct tdx_tsm { + struct device dev; +}; + +static struct tdx_tsm *alloc_tdx_tsm(void) +{ + struct tdx_tsm *tsm =3D kzalloc(sizeof(*tsm), GFP_KERNEL); + struct device *dev; + + if (!tsm) + return ERR_PTR(-ENOMEM); + + dev =3D &tsm->dev; + dev->bus =3D &tdx_subsys; + device_initialize(dev); + + return tsm; +} + +DEFINE_FREE(tdx_tsm_put, struct tdx_tsm *, + if (!IS_ERR_OR_NULL(_T)) put_device(&_T->dev)) +static struct tdx_tsm *init_tdx_tsm(void) +{ + struct device *dev; + int ret; + + struct tdx_tsm *tsm __free(tdx_tsm_put) =3D alloc_tdx_tsm(); + if (IS_ERR(tsm)) + return tsm; + + dev =3D &tsm->dev; + ret =3D dev_set_name(dev, "tdx_tsm"); + if (ret) + return ERR_PTR(ret); + + ret =3D device_add(dev); + if (ret) + return ERR_PTR(ret); + + return no_free_ptr(tsm); +} + +static void tdx_subsys_init(void) +{ + struct tdx_tsm *tdx_tsm; + int err; + + /* Establish subsystem for global TDX module attributes */ + err =3D subsys_virtual_register(&tdx_subsys, NULL); + if (err) { + pr_err("failed to register tdx_subsys %d\n", err); + return; + } + + /* Register 'tdx_tsm' for driving optional TDX Connect functionality */ + tdx_tsm =3D init_tdx_tsm(); + if (IS_ERR(tdx_tsm)) { + pr_err("failed to initialize TSM device (%pe)\n", tdx_tsm); + goto err_bus; + } + + return; + +err_bus: + bus_unregister(&tdx_subsys); +} + static int init_tdx_module(void) { int ret; @@ -1136,6 +1209,8 @@ static int init_tdx_module(void) =20 pr_info("%lu KB allocated for PAMT\n", tdmrs_count_pamt_kb(&tdx_tdmr_list= )); =20 + tdx_subsys_init(); + out_put_tdxmem: /* * @tdx_memlist is written here and read at memory hotplug time. --=20 2.47.1