Re: [RFC PATCH 04/15] virt: tdx-guest: Support devsec TSM for secure devices

[Xiaoyao Li]

On 9/24/2026 12:10 PM, Zhenzhong Duan wrote:
> Register Intel TDX secure device (devsec TSM) to the TSM framework and
> supply the tdx_devsec_ops callback operations. This enables control and
> management of the Trust Device Interface (TDI) through those hooks in
> accordance with the TDISP protocol.

It only implements the placeholders for these hooks. Please state them accurately.

> Check the TDCS configuration flags during driver initialization to
> ensure the hardware interface is supported before attempting device
> registration.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
> ---
>  arch/x86/include/asm/shared/tdx.h             |  1 +
>  drivers/virt/coco/tdx-guest/Kconfig           | 15 ++++
>  drivers/virt/coco/tdx-guest/Makefile          |  3 +
>  drivers/virt/coco/tdx-guest/connect.c         | 81 +++++++++++++++++++
>  .../coco/tdx-guest/{tdx-guest.c => main.c}    |  6 ++
>  drivers/virt/coco/tdx-guest/tdx-guest.h       | 20 +++++
>  6 files changed, 126 insertions(+)
>  create mode 100644 drivers/virt/coco/tdx-guest/connect.c
>  rename drivers/virt/coco/tdx-guest/{tdx-guest.c => main.c} (98%)
>  create mode 100644 drivers/virt/coco/tdx-guest/tdx-guest.h
> 
> diff --git a/arch/x86/include/asm/shared/tdx.h b/arch/x86/include/asm/shared/tdx.h
> index 665c12925ff6..499103f7a01b 100644
> --- a/arch/x86/include/asm/shared/tdx.h
> +++ b/arch/x86/include/asm/shared/tdx.h
> @@ -56,6 +56,7 @@
>  
>  /* TDCS_CONFIG_FLAGS bits */
>  #define TDCS_CONFIG_FLEXIBLE_PENDING_VE	BIT_ULL(1)
> +#define TDCS_CONFIG_TDX_CONNECT		BIT_ULL(5)
>  
>  /* TDCS_TD_CTLS bits */
>  #define TD_CTLS_PENDING_VE_DISABLE_BIT	0
> diff --git a/drivers/virt/coco/tdx-guest/Kconfig b/drivers/virt/coco/tdx-guest/Kconfig
> index dbbdc14383b1..2e9407f8bc70 100644
> --- a/drivers/virt/coco/tdx-guest/Kconfig
> +++ b/drivers/virt/coco/tdx-guest/Kconfig
> @@ -10,3 +10,18 @@ config TDX_GUEST_DRIVER
>  
>  	  To compile this driver as module, choose M here. The module will
>  	  be called tdx-guest.
> +
> +config TDX_CONNECT_GUEST
> +	bool "Intel TDX Connect Guest Support"
> +	depends on TDX_GUEST_DRIVER

maybe select TDX_GUEST_DRIVER ?

> +	depends on PCI_TSM
> +	default y
> +	help
> +	  Support Trust Device Interface (TDI) feature enumeration,
> +	  validation, and activation within an Intel TDX guest.
> +
> +	  This option enables the guest kernel to establish secure,
> +	  isolated connections with trusted devices assigned to the TD,
> +	  validating MMIO maps and authorizing DMA remapping tables.
> +
> +	  If unsure, say Y.
> diff --git a/drivers/virt/coco/tdx-guest/Makefile b/drivers/virt/coco/tdx-guest/Makefile
> index 775cb463f9c8..cfa991c7aeb5 100644
> --- a/drivers/virt/coco/tdx-guest/Makefile
> +++ b/drivers/virt/coco/tdx-guest/Makefile
> @@ -1,2 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-$(CONFIG_TDX_GUEST_DRIVER) += tdx-guest.o
> +
> +tdx-guest-y := main.o
> +tdx-guest-$(CONFIG_TDX_CONNECT_GUEST) += connect.o
> diff --git a/drivers/virt/coco/tdx-guest/connect.c b/drivers/virt/coco/tdx-guest/connect.c
> new file mode 100644
> index 000000000000..80ae7c19e179
> --- /dev/null
> +++ b/drivers/virt/coco/tdx-guest/connect.c
> @@ -0,0 +1,81 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * TDX Connect guest driver
> + *
> + * Copyright (C) 2026 Intel Corporation
> + */
> +
> +#define pr_fmt(fmt)		KBUILD_MODNAME ": tdx_connect: " fmt
> +
> +#include <linux/pci.h>
> +#include <linux/pci-tsm.h>
> +#include <linux/tsm.h>
> +#include <asm/tdx.h>
> +
> +#include "tdx-guest.h"
> +
> +struct tdx_devsec {
> +	struct pci_tsm_devsec pci;
> +};
> +
> +static struct tdx_devsec *to_tdx_devsec(struct pci_tsm *tsm)
> +{
> +	return container_of(tsm, struct tdx_devsec, pci.base_tsm);
> +}
> +
> +static struct pci_tsm *tdx_devsec_lock(struct tsm_dev *tsm_dev, struct pci_dev *pdev)
> +{
> +	int ret;
> +
> +	struct tdx_devsec *tdevsec __free(kfree) = kzalloc(sizeof(*tdevsec), GFP_KERNEL);
> +	if (!tdevsec)
> +		return ERR_PTR(-ENOMEM);
> +
> +	ret = pci_tsm_devsec_constructor(pdev, &tdevsec->pci, tsm_dev);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return &no_free_ptr(tdevsec)->pci.base_tsm;
> +}
> +
> +static void tdx_devsec_unlock(struct pci_tsm *tsm)
> +{
> +	struct tdx_devsec *tdevsec = to_tdx_devsec(tsm);
> +
> +	kfree(tdevsec);
> +}
> +
> +static int tdx_devsec_run(struct pci_dev *pdev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static struct pci_tsm_ops tdx_devsec_ops = {
> +	.lock = tdx_devsec_lock,
> +	.unlock = tdx_devsec_unlock,
> +	.run = tdx_devsec_run,
> +};
> +
> +static void devsec_tsm_remove(void *tsm_dev)
> +{
> +	tsm_unregister(tsm_dev);
> +}
> +
> +int tdx_connect_init(struct device *dev)
> +{
> +	struct tsm_dev *tsm_dev;
> +	u64 config, ret;
> +
> +	ret = tdg_vm_rd(TDCS_CONFIG_FLAGS, &config);
> +	if (ret)
> +		return -EIO;

The kernel already manadates and assumes TDCS_CONFIG_FLAGS is always supported
in disable_sept_ve().

Can we make them consistent? Maybe just treat config as 0 when reading
TDCS_CONFIG_FLAGS fails?

> +
> +	if (!(config & TDCS_CONFIG_TDX_CONNECT))
> +		return 0;
> +
> +	tsm_dev = tsm_register(dev, &tdx_devsec_ops);
> +	if (IS_ERR(tsm_dev))
> +		return PTR_ERR(tsm_dev);
> +
> +	return devm_add_action_or_reset(dev, devsec_tsm_remove, tsm_dev);
> +}
> diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.c b/drivers/virt/coco/tdx-guest/main.c
> similarity index 98%
> rename from drivers/virt/coco/tdx-guest/tdx-guest.c
> rename to drivers/virt/coco/tdx-guest/main.c
> index d0303e31e816..801a1f2b5f3d 100644
> --- a/drivers/virt/coco/tdx-guest/tdx-guest.c
> +++ b/drivers/virt/coco/tdx-guest/main.c
> @@ -25,6 +25,8 @@
>  #include <asm/cpu_device_id.h>
>  #include <asm/tdx.h>
>  
> +#include "tdx-guest.h"
> +
>  /* TDREPORT buffer */
>  static u8 *tdx_report_buf;
>  
> @@ -428,6 +430,10 @@ static int __init tdx_guest_init(void)
>  	if (ret)
>  		goto free_quote;
>  
> +	ret = tdx_connect_init(tdx_misc_dev.this_device);
> +	if (ret)
> +		pr_warn("Failed to enable TDX Connect: %d\n", ret);
> +
>  	return 0;
>  
>  free_quote:
> diff --git a/drivers/virt/coco/tdx-guest/tdx-guest.h b/drivers/virt/coco/tdx-guest/tdx-guest.h
> new file mode 100644
> index 000000000000..4218541c7f3b
> --- /dev/null
> +++ b/drivers/virt/coco/tdx-guest/tdx-guest.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * TDX guest driver private declarations
> + *
> + * Copyright (C) 2026 Intel Corporation
> + */
> +
> +#ifndef __TDX_GUEST_H
> +#define __TDX_GUEST_H
> +
> +#include <linux/kernel.h>
> +#include <linux/device.h>
> +
> +#ifdef CONFIG_TDX_CONNECT_GUEST
> +extern int tdx_connect_init(struct device *dev);

extern is not needed.

> +#else
> +static inline int tdx_connect_init(struct device *dev) { return 0; }
> +#endif /* CONFIG_TDX_CONNECT_GUEST */
> +
> +#endif /* __TDX_GUEST_H */