From: Chao Gao 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 TEE Secure Manager (TSM). Create a virtual device not only to align with other implementations but also to make it easier to - expose metadata (e.g., TDX module version, seamldr version etc) to the userspace as device attributes - implement firmware uploader APIs which are tied to a device. This is needed to support TDX module runtime updates - enable TDX Connect which will share a common infrastructure with other platform implementations. In the TDX Connect context, every architecture has a TSM, represented by a PCIe or virtual device. The new "tdx_host" device will serve the TSM role. A faux device is used as for TDX because the TDX module is singular within the system and lacks associated platform resources. Using a faux device eliminates the need to create a stub bus. The call to tdx_enable() makes the new module independent of kvm_intel.ko. For example, TDX Connect may be used to established to PCIe link encryption even if a TVM is never launched. For now, just create the common loading infrastructure. [ Yilun: Remove unnecessary head files ] Co-developed-by: Xu Yilun Signed-off-by: Xu Yilun Signed-off-by: Chao Gao Signed-off-by: Dan Williams --- drivers/virt/coco/Kconfig | 2 ++ drivers/virt/coco/tdx-host/Kconfig | 10 +++++++ drivers/virt/coco/Makefile | 1 + drivers/virt/coco/tdx-host/Makefile | 1 + drivers/virt/coco/tdx-host/tdx-host.c | 41 +++++++++++++++++++++++++++ 5 files changed, 55 insertions(+) create mode 100644 drivers/virt/coco/tdx-host/Kconfig create mode 100644 drivers/virt/coco/tdx-host/Makefile create mode 100644 drivers/virt/coco/tdx-host/tdx-host.c diff --git a/drivers/virt/coco/Kconfig b/drivers/virt/coco/Kconfig index bb0c6d6ddcc8..b9fb0760e917 100644 --- a/drivers/virt/coco/Kconfig +++ b/drivers/virt/coco/Kconfig @@ -15,5 +15,7 @@ source "drivers/virt/coco/arm-cca-guest/Kconfig" source "drivers/virt/coco/guest/Kconfig" +source "drivers/virt/coco/tdx-host/Kconfig" + config TSM bool diff --git a/drivers/virt/coco/tdx-host/Kconfig b/drivers/virt/coco/tdx-host/Kconfig new file mode 100644 index 000000000000..bf6be0fc0879 --- /dev/null +++ b/drivers/virt/coco/tdx-host/Kconfig @@ -0,0 +1,10 @@ +config TDX_HOST_SERVICES + tristate "TDX Host Services Driver" + depends on INTEL_TDX_HOST + default m if INTEL_TDX_HOST + help + Enable access to TDX host services like module update and + extensions (e.g. TDX Connect). + + Say y or m if enabling support for confidential virtual machine + support (CONFIG_INTEL_TDX_HOST). The module is called tdx_host.ko diff --git a/drivers/virt/coco/Makefile b/drivers/virt/coco/Makefile index cb52021912b3..b323b0ae4f82 100644 --- a/drivers/virt/coco/Makefile +++ b/drivers/virt/coco/Makefile @@ -6,6 +6,7 @@ obj-$(CONFIG_EFI_SECRET) += efi_secret/ obj-$(CONFIG_ARM_PKVM_GUEST) += pkvm-guest/ obj-$(CONFIG_SEV_GUEST) += sev-guest/ obj-$(CONFIG_INTEL_TDX_GUEST) += tdx-guest/ +obj-$(CONFIG_INTEL_TDX_HOST) += tdx-host/ obj-$(CONFIG_ARM_CCA_GUEST) += arm-cca-guest/ obj-$(CONFIG_TSM) += tsm-core.o obj-$(CONFIG_TSM_GUEST) += guest/ diff --git a/drivers/virt/coco/tdx-host/Makefile b/drivers/virt/coco/tdx-host/Makefile new file mode 100644 index 000000000000..e61e749a8dff --- /dev/null +++ b/drivers/virt/coco/tdx-host/Makefile @@ -0,0 +1 @@ +obj-$(CONFIG_TDX_HOST_SERVICES) += tdx-host.o diff --git a/drivers/virt/coco/tdx-host/tdx-host.c b/drivers/virt/coco/tdx-host/tdx-host.c new file mode 100644 index 000000000000..ced1c980dc6f --- /dev/null +++ b/drivers/virt/coco/tdx-host/tdx-host.c @@ -0,0 +1,41 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TDX host user interface driver + * + * Copyright (C) 2025 Intel Corporation + */ + +#include +#include +#include +#include + +static const struct x86_cpu_id tdx_host_ids[] = { + X86_MATCH_FEATURE(X86_FEATURE_TDX_HOST_PLATFORM, NULL), + {} +}; +MODULE_DEVICE_TABLE(x86cpu, tdx_host_ids); + +static struct faux_device *fdev; + +static int __init tdx_host_init(void) +{ + if (!x86_match_cpu(tdx_host_ids)) + return -ENODEV; + + fdev = faux_device_create(KBUILD_MODNAME, NULL, NULL); + if (!fdev) + return -ENODEV; + + return 0; +} +module_init(tdx_host_init); + +static void __exit tdx_host_exit(void) +{ + faux_device_destroy(fdev); +} +module_exit(tdx_host_exit); + +MODULE_DESCRIPTION("TDX Host Services"); +MODULE_LICENSE("GPL"); -- 2.25.1