From 59783353467958517a3e511394d7ab3aed03bc6a Mon Sep 17 00:00:00 2001 From: Chao Gao Date: Wed, 20 May 2026 15:28:52 -0700 Subject: [PATCH] coco/tdx-host: Introduce a "tdx_host" device TDX depends on a platform firmware module that runs on the CPU. Unlike other CoCo architectures, TDX has no hardware "device" running the show, just a blob on the CPU. Create a virtual device to anchor interactions with this platform firmware. This lets later code: - expose metadata: TDX module version, seamldr version, to userspace as device attributes - implement firmware uploader APIs (which are tied to a device) to support TDX module runtime updates Use a faux device because the TDX module is singular within the system and has no platform resources. Using a faux device eliminates the need to create a stub bus. The call to tdx_get_sysinfo() ensures that the TDX module is ready to provide services. Note that AMD has a PCI device for the PSP for SEV and ARM CCA will likely have a faux device [1]. Thanks to Dan and Yilun for all the help on this one. [ dhansen: trim changelog ] Signed-off-by: Chao Gao Signed-off-by: Dave Hansen Reviewed-by: Jonathan Cameron Reviewed-by: Tony Lindgren Reviewed-by: Xu Yilun Reviewed-by: Kai Huang Reviewed-by: Kiryl Shutsemau (Meta) Reviewed-by: Xiaoyao Li Link: https://lore.kernel.org/all/2025073035-bulginess-rematch-b92e@gregkh/ # [1] Link: https://patch.msgid.link/20260520133909.409394-7-chao.gao@intel.com --- arch/x86/virt/vmx/tdx/tdx.c | 2 +- drivers/virt/coco/Kconfig | 2 ++ drivers/virt/coco/Makefile | 1 + drivers/virt/coco/tdx-host/Kconfig | 4 +++ drivers/virt/coco/tdx-host/Makefile | 1 + drivers/virt/coco/tdx-host/tdx-host.c | 43 +++++++++++++++++++++++++++ 6 files changed, 52 insertions(+), 1 deletion(-) 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/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index b329791db9c2..5fb0441a9ac6 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -1527,7 +1527,7 @@ const struct tdx_sys_info *tdx_get_sysinfo(void) return (const struct tdx_sys_info *)&tdx_sysinfo; } -EXPORT_SYMBOL_FOR_KVM(tdx_get_sysinfo); +EXPORT_SYMBOL_FOR_MODULES(tdx_get_sysinfo, "kvm-intel,tdx-host"); u32 tdx_get_nr_guest_keyids(void) { diff --git a/drivers/virt/coco/Kconfig b/drivers/virt/coco/Kconfig index df1cfaf26c65..f7691f64fbe3 100644 --- a/drivers/virt/coco/Kconfig +++ b/drivers/virt/coco/Kconfig @@ -17,5 +17,7 @@ source "drivers/virt/coco/arm-cca-guest/Kconfig" source "drivers/virt/coco/guest/Kconfig" endif +source "drivers/virt/coco/tdx-host/Kconfig" + config TSM bool 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/Kconfig b/drivers/virt/coco/tdx-host/Kconfig new file mode 100644 index 000000000000..cfe81b9c0364 --- /dev/null +++ b/drivers/virt/coco/tdx-host/Kconfig @@ -0,0 +1,4 @@ +config TDX_HOST_SERVICES + tristate + depends on INTEL_TDX_HOST + default m 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..c77885392b09 --- /dev/null +++ b/drivers/virt/coco/tdx-host/tdx-host.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TDX host user interface driver + * + * Copyright (C) 2025 Intel Corporation + */ + +#include +#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) || !tdx_get_sysinfo()) + 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");