Pull PCIe Link Encryption and Device Authentication from Dan Williams:
 "New PCI infrastructure and one architecture implementation for PCIe
  link encryption establishment via platform firmware services.

  This work is the result of multiple vendors coming to consensus on
  some core infrastructure (thanks Alexey, Yilun, and Aneesh!), and
  three vendor implementations, although only one is included in this
  pull. The PCI core changes have an ack from Bjorn, the crypto/ccp/
  changes have an ack from Tom, and the iommu/amd/ changes have an ack
  from Joerg.

  PCIe link encryption is made possible by the soup of acronyms
  mentioned in the shortlog below. Link Integrity and Data Encryption
  (IDE) is a protocol for installing keys in the transmitter and
  receiver at each end of a link. That protocol is transported over Data
  Object Exchange (DOE) mailboxes using PCI configuration requests.

  The aspect that makes this a "platform firmware service" is that the
  key provisioning and protocol is coordinated through a Trusted
  Execution Envrionment (TEE) Security Manager (TSM). That is either
  firmware running in a coprocessor (AMD SEV-TIO), or quasi-hypervisor
  software (Intel TDX Connect / ARM CCA) running in a protected CPU
  mode.

  Now, the only reason to ask a TSM to run this protocol and install the
  keys rather than have a Linux driver do the same is so that later, a
  confidential VM can ask the TSM directly "can you certify this
  device?".

  That precludes host Linux from provisioning its own keys, because host
  Linux is outside the trust domain for the VM. It also turns out that
  all architectures, save for one, do not publish a mechanism for an OS
  to establish keys in the root port. So "TSM-established link
  encryption" is the only cross-architecture path for this capability
  for the foreseeable future.

  This unblocks the other arch implementations to follow in v6.20/v7.0,
  once they clear some other dependencies, and it unblocks the next
  phase of work to implement the end-to-end flow of confidential device
  assignment. The PCIe specification calls this end-to-end flow Trusted
  Execution Environment (TEE) Device Interface Security Protocol
  (TDISP).

  In the meantime, Linux gets a link encryption facility which has
  practical benefits along the same lines as memory encryption. It
  authenticates devices via certificates and may protect against
  interposer attacks trying to capture clear-text PCIe traffic.

  Summary:

   - Introduce the PCI/TSM core for the coordination of device
     authentication, link encryption and establishment (IDE), and later
     management of the device security operational states (TDISP).
     Notify the new TSM core layer of PCI device arrival and departure

   - Add a low level TSM driver for the link encryption establishment
     capabilities of the AMD SEV-TIO architecture

   - Add a library of helpers TSM drivers to use for IDE establishment
     and the DOE transport

   - Add skeleton support for 'bind' and 'guest_request' operations in
     support of TDISP"

* tag 'tsm-for-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/devsec/tsm: (23 commits)
  crypto/ccp: Fix CONFIG_PCI=n build
  virt: Fix Kconfig warning when selecting TSM without VIRT_DRIVERS
  crypto/ccp: Implement SEV-TIO PCIe IDE (phase1)
  iommu/amd: Report SEV-TIO support
  psp-sev: Assign numbers to all status codes and add new
  ccp: Make snp_reclaim_pages and __sev_do_cmd_locked public
  PCI/TSM: Add 'dsm' and 'bound' attributes for dependent functions
  PCI/TSM: Add pci_tsm_guest_req() for managing TDIs
  PCI/TSM: Add pci_tsm_bind() helper for instantiating TDIs
  PCI/IDE: Initialize an ID for all IDE streams
  PCI/IDE: Add Address Association Register setup for downstream MMIO
  resource: Introduce resource_assigned() for discerning active resources
  PCI/TSM: Drop stub for pci_tsm_doe_transfer()
  drivers/virt: Drop VIRT_DRIVERS build dependency
  PCI/TSM: Report active IDE streams
  PCI/IDE: Report available IDE streams
  PCI/IDE: Add IDE establishment helpers
  PCI: Establish document for PCI host bridge sysfs attributes
  PCI: Add PCIe Device 3 Extended Capability enumeration
  PCI/TSM: Establish Secure Sessions and Link Encryption
  ...

When a device is hot-plugged, the drivers_autoprobe sysfs attribute is
not checked (at least for PCI devices). This means that
drivers_autoprobe is not working as intended, e.g. hot-plugged PCI
devices will still be autoprobed and bound to drivers even with
drivers_autoprobe disabled.

The problem likely started when device_add() was removed from
pci_bus_add_device() in commit 4f535093cf8f ("PCI: Put pci_dev in device
tree as early as possible") which means that the check for
drivers_autoprobe which used to happen in bus_probe_device() is no
longer present (previously bus_add_device() calls bus_probe_device()).
Conveniently, in commit 91703041697c ("PCI: Allow built-in drivers to
use async initial probing") device_attach() was replaced with
device_initial_probe() which faciliates this change to push the check
for drivers_autoprobe into device_initial_probe().

Make sure all devices check drivers_autoprobe by pushing the
drivers_autoprobe check into device_initial_probe(). This will only
affect devices on the PCI bus for now as device_initial_probe() is only
called by pci_bus_add_device() and bus_probe_device(), but
bus_probe_device() already checks for autoprobe, so callers of
bus_probe_device() should not observe changes on autoprobing.
Note also that pushing this check into device_initial_probe() rather
than device_attach() makes it only affect automatic probing of
drivers (e.g. when a device is hot-plugged), userspace can still choose
to manually bind a driver by writing to drivers_probe sysfs attribute,
even with autoprobe disabled.

Any future callers of device_initial_probe() will respect the
drivers_autoprobe sysfs attribute, which is the intended purpose of
drivers_autoprobe.

Signed-off-by: Vincent Liu <vincent.liu@nutanix.com>
Link: https://patch.msgid.link/20251022120740.2476482-1-vincent.liu@nutanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

PCI/TSM, the PCI core functionality for the PCIe TEE Device Interface
Security Protocol (TDISP), has a need to walk all subordinate functions of
a Device Security Manager (DSM) to setup a device security context. A DSM
is physical function 0 of multi-function or SR-IOV device endpoint, or it
is an upstream switch port.

In error scenarios or when a TEE Security Manager (TSM) device is removed
it needs to unwind all established DSM contexts.

Introduce reverse versions of PCI device iteration helpers to mirror the
setup path and ensure that dependent children are handled before parents.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20251031212902.2256310-4-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

If userspace reads "uevent" device attribute at the same time as another
threads unbinds the device from its driver, change to dev->driver from a
valid pointer to NULL may result in crash. Fix this by using READ_ONCE()
when fetching the pointer, and take bus' drivers klist lock to make sure
driver instance will not disappear while we access it.

Use WRITE_ONCE() when setting the driver pointer to ensure there is no
tearing.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20250311052417.1846985-3-dmitry.torokhov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix spelling, "subystem" -> "subsystem"

Signed-off-by: Bharadwaj Raju <bharadwaj.raju777@gmail.com>
Link: https://lore.kernel.org/r/20250203220312.1052986-1-bharadwaj.raju777@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There are several for_each APIs which has parameter with type below:
int (*fn)(struct device *dev, void *data)
They iterate over various device lists and call @fn() for each device
with caller provided data @*data, and they usually need to modify @*data.

Give the type an dedicated typedef with advantages shown below:
typedef int (*device_iter_t)(struct device *dev, void *data)

- Shorter API declarations and definitions
- Prevent further for_each APIs from using bad parameter type

So introduce device_iter_t and apply it to various existing APIs below:
bus_for_each_dev()
(class|driver)_for_each_device()
device_for_each_child(_reverse|_reverse_from)().

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250105-class_fix-v6-7-3a2f1768d4d4@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For bus_find_device(), driver_find_device(), and device_find_child(), all
of their function body have pattern below:

{
	struct klist_iter i;
	struct device *dev;

	...
	while ((dev = next_device(&i)))
		if (match(dev, data) && get_device(dev))
			break;
	...
}

The expression 'get_device(dev)' in the if condition always returns true
since @dev != NULL.

Move the expression to if body to make logic of these APIs more clearer.

Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250105-class_fix-v6-3-3a2f1768d4d4@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There are several drivers/base APIs for finding a specific device, and
they currently use the following good type for the @match parameter:
int (*match)(struct device *dev, const void *data)

Since these operations do not modify the caller-provided @*data, this
type is worthy of a dedicated typedef:
typedef int (*device_match_t)(struct device *dev, const void *data)

Advantages of using device_match_t:
 - Shorter API declarations and definitions
 - Prevent further APIs from using a bad type for @match

So introduce device_match_t and apply it to the existing
(bus|class|driver|auxiliary)_find_device() APIs.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240813-dev_match_api-v3-1-6c6878a99b9f@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For bus_register(), any error which happens after kset_register() will
cause that @priv are freed twice, fixed by setting @priv with NULL after
the first free.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240727-bus_register_fix-v1-1-fed8dd0dba7a@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add simple error handling for buses_init() since it is easy to do.

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240727-buses_init-v1-1-e863295a2c0e@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>