fb82437fdd ("PCI: Change capability register offsets to hex") incorrectly
converted the PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 value from decimal 52 to hex
0x32:
-#define PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 52 /* v2 endpoints with link end here */
+#define PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 0x32 /* end of v2 EPs w/ link */
This broke PCI capabilities in a VMM because subsequent ones weren't
DWORD-aligned.
Change PCI_CAP_EXP_ENDPOINT_SIZEOF_V2 to the correct value of 0x34.
fb82437fdd was from Baruch Siach <baruch@tkos.co.il>, but this was not
Baruch's fault; it's a mistake I made when applying the patch.
Fixes: fb82437fdd ("PCI: Change capability register offsets to hex")
Reported-by: David Woodhouse <dwmw2@infradead.org>
Closes: https://lore.kernel.org/all/3ae392a0158e9d9ab09a1d42150429dd8ca42791.camel@infradead.org
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Pull CXL updates from Dave Jiang:
- Introduce cxl_memdev_attach and pave way for soft reserved handling,
type2 accelerator enabling, and LSA 2.0 enabling. All these series
require the endpoint driver to settle before continuing the memdev
driver probe.
- Address CXL port error protocol handling and reporting.
The large patch series was split into three parts. The first two
parts are included here with the final part coming later.
The first part consists of a series of code refactoring to PCI AER
sub-system that addresses CXL and also CXL RAS code to prepare for
port error handling.
The second part refactors the CXL code to move management of
component registers to cxl_port objects to allow all CXL AER errors
to be handled through the cxl_port hierarchy.
- Provide AMD Zen5 platform address translation for CXL using ACPI
PRMT. This includes a conventions document to explain why this is
needed and how it's implemented.
- Misc CXL patches of fixes, cleanups, and updates. Including CXL
address translation for unaligned MOD3 regions.
[ TLA service: CXL is "Compute Express Link" ]
* tag 'cxl-for-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (59 commits)
cxl: Disable HPA/SPA translation handlers for Normalized Addressing
cxl/region: Factor out code into cxl_region_setup_poison()
cxl/atl: Lock decoders that need address translation
cxl: Enable AMD Zen5 address translation using ACPI PRMT
cxl/acpi: Prepare use of EFI runtime services
cxl: Introduce callback for HPA address ranges translation
cxl/region: Use region data to get the root decoder
cxl/region: Add @hpa_range argument to function cxl_calc_interleave_pos()
cxl/region: Separate region parameter setup and region construction
cxl: Simplify cxl_root_ops allocation and handling
cxl/region: Store HPA range in struct cxl_region
cxl/region: Store root decoder in struct cxl_region
cxl/region: Rename misleading variable name @hpa to @hpa_range
Documentation/driver-api/cxl: ACPI PRM Address Translation Support and AMD Zen5 enablement
cxl, doc: Moving conventions in separate files
cxl, doc: Remove isonum.txt inclusion
cxl/port: Unify endpoint and switch port lookup
cxl/port: Move endpoint component register management to cxl_port
cxl/port: Map Port RAS registers
cxl/port: Move dport RAS setup to dport add time
...
CXL is a protocol that runs on top of PCIe electricals. Its error model
also runs on top of the PCIe AER error model by standardizing "internal"
errors as "CXL" errors. Linux has historically ignored internal errors.
CXL protocol error handling is then a task of enhancing the PCIe AER
core to understand that PCIe ports (upstream and downstream) and
endpoints may throw internal errors that represent standard CXL protocol
errors.
The proposed method to make that determination is to teach 'struct
pci_dev' to cache when its link has trained the CXL.mem and/or CXL.cache
protocols and then treat all internal errors as CXL errors. A design
goal is to not burden the PCIe AER core with CXL knowledge beyond just
enough to forward error notifications to the CXL RAS core. The forwarded
notification looks up a 'struct cxl_port' or 'struct cxl_dport'
companion device to the PCI device.
Introduce set_pcie_cxl() with logic checking for CXL.mem or CXL.cache
status in the CXL Flex Bus DVSEC status register. The CXL Flex Bus DVSEC
presence is used because it is required for all the CXL PCIe devices.[1]
[1] CXL 3.1 Spec, 8.1.1 PCIe Designated Vendor-Specific Extended
Capability (DVSEC) ID Assignment, Table 8-2
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Alejandro Lucero <alucerop@amd.com>
Reviewed-by: Ben Cheatham <benjamin.cheatham@amd.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260114182055.46029-4-terry.bowman@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
CXL DVSEC definitions were recently moved into uapi/pci_regs.h, but the
newly added macros do not follow the file's existing naming conventions.
The current format uses CXL_DVSEC_XYZ, while the new CXL entries must
instead use the PCI_DVSEC_CXL_XYZ prefix to match the conventions already
established in pci_regs.h.
The new CXL DVSEC macros also introduce _MASK and _OFFSET suffixes, which
are not used anywhere else in the file. These suffixes lengthen the
identifiers and reduce readability. Remove _MASK and _OFFSET from the
recently added definitions.
Additionally, remove PCI_DVSEC_HEADER1_LENGTH, as it duplicates the existing
PCI_DVSEC_HEADER1_LEN() macro.
Update all existing references to use the new macro names.
Finally, update the inline documentation to reference the latest revision
of the CXL specification.
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20260114182055.46029-3-terry.bowman@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
The PCIe 7.0 specification, section 11, defines the Trusted Execution
Environment (TEE) Device Interface Security Protocol (TDISP). This
protocol definition builds upon Component Measurement and Authentication
(CMA), and link Integrity and Data Encryption (IDE). It adds support for
assigning devices (PCI physical or virtual function) to a confidential VM
such that the assigned device is enabled to access guest private memory
protected by technologies like Intel TDX, AMD SEV-SNP, RISCV COVE, or ARM
CCA.
The "TSM" (TEE Security Manager) is a concept in the TDISP specification
of an agent that mediates between a "DSM" (Device Security Manager) and
system software in both a VMM and a confidential VM. A VMM uses TSM ABIs
to setup link security and assign devices. A confidential VM uses TSM
ABIs to transition an assigned device into the TDISP "RUN" state and
validate its configuration. From a Linux perspective the TSM abstracts
many of the details of TDISP, IDE, and CMA. Some of those details leak
through at times, but for the most part TDISP is an internal
implementation detail of the TSM.
CONFIG_PCI_TSM adds an "authenticated" attribute and "tsm/" subdirectory
to pci-sysfs. Consider that the TSM driver may itself be a PCI driver.
Userspace can watch for the arrival of a "TSM" device,
/sys/class/tsm/tsm0/uevent KOBJ_CHANGE, to know when the PCI core has
initialized TSM services.
The operations that can be executed against a PCI device are split into
two mutually exclusive operation sets, "Link" and "Security" (struct
pci_tsm_{link,security}_ops). The "Link" operations manage physical link
security properties and communication with the device's Device Security
Manager firmware. These are the host side operations in TDISP. The
"Security" operations coordinate the security state of the assigned
virtual device (TDI). These are the guest side operations in TDISP.
Only "link" (Secure Session and physical Link Encryption) operations are
defined at this stage. There are placeholders for the device security
(Trusted Computing Base entry / exit) operations.
The locking allows for multiple devices to be executing commands
simultaneously, one outstanding command per-device and an rwsem
synchronizes the implementation relative to TSM registration/unregistration
events.
Thanks to Wu Hao for his work on an early draft of this support.
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Samuel Ortiz <sameo@rivosinc.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
Link: https://patch.msgid.link/20251031212902.2256310-5-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link encryption is a new PCIe feature enumerated by "PCIe r7.0 section
7.9.26 IDE Extended Capability".
It is both a standalone port + endpoint capability, and a building block
for the security protocol defined by "PCIe r7.0 section 11 TEE Device
Interface Security Protocol (TDISP)". That protocol coordinates device
security setup between a platform TSM (TEE Security Manager) and a
device DSM (Device Security Manager). While the platform TSM can
allocate resources like Stream ID and manage keys, it still requires
system software to manage the IDE capability register block.
Add register definitions and basic enumeration in preparation for
Selective IDE Stream establishment. A follow on change selects the new
CONFIG_PCI_IDE symbol. Note that while the IDE specification defines
both a point-to-point "Link Stream" and a Root Port to endpoint
"Selective Stream", only "Selective Stream" is considered for Linux as
that is the predominant mode expected by Trusted Execution Environment
Security Managers (TSMs), and it is the security model that limits the
number of PCI components within the TCB in a PCIe topology with
switches.
Co-developed-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Co-developed-by: Xu Yilun <yilun.xu@linux.intel.com>
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Link: https://patch.msgid.link/20251031212902.2256310-3-dan.j.williams@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
- Simplify __pci_find_next_cap_ttl() by replacing magic numbers with
#defines, extracting fields with FIELD_GET(), etc (Hans Zhang)
- Convert __pci_find_next_cap_ttl() to a PCI_FIND_NEXT_CAP() macro that
takes a config space accessor function so we can also use it in cases
where the usual config accessors aren't available (Hans Zhang)
- Similarly convert pci_find_next_ext_capability() to a
PCI_FIND_NEXT_EXT_CAP() macro (Hans Zhang)
- Implement dwc, dwc endpoint, and cadence capability search interfaces on
top of PCI_FIND_NEXT_CAP() and PCI_FIND_NEXT_EXT_CAP(), replacing the
previous duplicated code (Hans Zhang)
- Search for capabilities in the cadence core instead of hard-coding their
offsets, which are subject to change (Hans Zhang)
* pci/capability-search:
PCI: cadence: Use cdns_pcie_find_*capability() to avoid hardcoding offsets
PCI: cadence: Implement capability search using PCI core APIs
PCI: dwc: ep: Implement capability search using PCI core APIs
PCI: dwc: Implement capability search using PCI core APIs
PCI: Refactor extended capability search into PCI_FIND_NEXT_EXT_CAP()
PCI: Refactor capability search into PCI_FIND_NEXT_CAP()
PCI: Clean up __pci_find_next_cap_ttl() readability
When reporting an error, the AER driver prints the TLP Header / Prefix Log
only for errors enumerated in the AER_LOG_TLP_MASKS macro.
The macro was never amended since its introduction in 2006 with commit
6c2b374d74 ("PCI-Express AER implemetation: AER core and aerdriver").
At the time, PCIe r1.1 was the latest spec revision.
Amend the macro with errors defined since then to avoid omitting the TLP
Header / Prefix Log for newer errors.
The order of the errors in AER_LOG_TLP_MASKS follows PCIe r1.1 sec 6.2.7
rather than 7.10.2, because only the former documents for which errors a
TLP Header / Prefix is logged. Retain this order. The section number is
still 6.2.7 in today's PCIe r7.0.
For Completion Timeouts, the TLP Header / Prefix is only logged if the
Completion Timeout Prefix / Header Log Capable bit is set in the AER
Capabilities and Control register. Introduce a tlp_header_logged() helper
to check whether the TLP Header / Prefix Log is populated and use it in
the two places which currently match against AER_LOG_TLP_MASKS directly.
For Uncorrectable Internal Errors, logging of the TLP Header / Prefix is
optional per PCIe r7.0 sec 6.2.7. If needed, drivers could indicate
through a flag whether devices are capable and tlp_header_logged() could
then check that flag.
pcitools introduced macros for newer errors with commit 144b0911cc0b
("ls-ecaps: extend decode support for more fields for AER CE and UE
status"):
https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/commit/?id=144b0911cc0b
Unfortunately some of those macros are overly long:
PCI_ERR_UNC_POISONED_TLP_EGRESS
PCI_ERR_UNC_DMWR_REQ_EGRESS_BLOCKED
PCI_ERR_UNC_IDE_CHECK
PCI_ERR_UNC_MISR_IDE_TLP
PCI_ERR_UNC_PCRC_CHECK
PCI_ERR_UNC_TLP_XLAT_EGRESS_BLOCKED
This seems unsuitable for <linux/pci_regs.h>, so shorten to:
PCI_ERR_UNC_POISON_BLK
PCI_ERR_UNC_DMWR_BLK
PCI_ERR_UNC_IDE_CHECK
PCI_ERR_UNC_MISR_IDE
PCI_ERR_UNC_PCRC_CHECK
PCI_ERR_UNC_XLAT_BLK
Note that some of the existing macros in <linux/pci_regs.h> do not match
exactly with pcitools (e.g. PCI_ERR_UNC_SDES versus PCI_ERR_UNC_SURPDN),
so it does not seem mandatory for them to be identical.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/5f707caf1260bd8f15012bb032f7da9a9b898aba.1756712066.git.lukas@wunner.de
- Use pci_resource_n() to simplify BAR/window resource lookup (Ilpo
Järvinen)
- Fix typo that repeatedly distributed resources to a bridge instead of
iterating over subordinate bridges, which resulted in too little space to
assign some BARs (Kai-Heng Feng)
- Relax bridge window tail sizing for optional resources, e.g., IOV BARs,
to avoid failures when removing and re-adding devices (Ilpo Järvinen)
- Fix a double counting error for I/O resources, as we previously did for
memory resources (Ilpo Järvinen)
- Use resource_set_{range,size}() helpers in more places (Ilpo Järvinen)
- Add pci_resource_is_iov() to identify IOV resources (Ilpo Järvinen)
- Add pci_resource_num() to look up the BAR number from the resource
pointer (Ilpo Järvinen)
- Add restore_dev_resource() to simplify code that resources saved device
resources (Ilpo Järvinen)
- Allow drivers to enable devices even if we haven't assigned optional IOV
resources to them (Ilpo Järvinen)
- Improve debug output during resource reallocation (Ilpo Järvinen)
- Rework handling of optional resources (IOV BARs, ROMs) to reduce failures
if we can't allocate them (Ilpo Järvinen)
- Move declarations of pci_rescan_bus_bridge_resize(),
pci_reassign_bridge_resources(), and CardBus-related sizes from
include/linux/pci.h to drivers/pci/pci.h since they're not used outside
the PCI core (Ilpo Järvinen)
- Make pci_setup_bridge() static (Ilpo Järvinen)
- Fix a NULL dereference in the SR-IOV VF creation error path (Shay Drory)
- Fix s390 mmio_read/write syscalls, which didn't cause page faults in some
cases, which broke vfio-pci lazy mapping on first access (Niklas
Schnelle)
- Add pdev->non_mappable_bars to replace CONFIG_VFIO_PCI_MMAP, which was
disabled only for s390 (Niklas Schnelle)
- Support mmap of PCI resources on s390 except for ISM devices (Niklas
Schnelle)
* pci/resource:
s390/pci: Support mmap() of PCI resources except for ISM devices
s390/pci: Introduce pdev->non_mappable_bars and replace VFIO_PCI_MMAP
s390/pci: Fix s390_mmio_read/write syscall page fault handling
PCI: Fix NULL dereference in SR-IOV VF creation error path
PCI: Move cardbus IO size declarations into pci/pci.h
PCI: Make pci_setup_bridge() static
PCI: Move resource reassignment func declarations into pci/pci.h
PCI: Move pci_rescan_bus_bridge_resize() declaration to pci/pci.h
PCI: Fix BAR resizing when VF BARs are assigned
PCI: Do not claim to release resource falsely
PCI: Increase Resizable BAR support from 512 GB to 128 TB
PCI: Rework optional resource handling
PCI: Perform reset_resource() and build fail list in sync
PCI: Use res->parent to check if resource is assigned
PCI: Add debug print when releasing resources before retry
PCI: Indicate optional resource assignment failures
PCI: Always have realloc_head in __assign_resources_sorted()
PCI: Extend enable to check for any optional resource
PCI: Add restore_dev_resource()
PCI: Remove incorrect comment from pci_reassign_resource()
PCI: Consolidate assignment loop next round preparation
PCI: Rename retval to ret
PCI: Use while loop and break instead of gotos
PCI: Refactor pdev_sort_resources() & __dev_sort_resources()
PCI: Converge return paths in __assign_resources_sorted()
PCI: Add dev & res local variables to resource assignment funcs
PCI: Add pci_resource_num() helper
PCI: Check resource_size() separately
PCI: Add pci_resource_is_iov() to identify IOV resources
PCI: Use resource_set_{range,size}() helpers
PCI: Use SZ_* instead of literals in setup-bus.c
PCI: Fix old_size lower bound in calculate_iosize() too
PCI: Allow relaxed bridge window tail sizing for optional resources
PCI: Simplify size1 assignment logic
PCI: Use min_align, not unrelated add_align, for size0
PCI: Remove add_align overwrite unrelated to size0
PCI: Use downstream bridges for distributing resources
PCI: Cleanup dev->resource + resno to use pci_resource_n()
- Rename DOE 'protocol' to 'feature' to follow spec terminology (Alistair
Francis)
- Expose supported DOE features via sysfs (Alistair Francis)
- Allow DOE support to be enabled even if CXL isn't enabled (Alistair
Francis)
* pci/doe:
PCI/DOE: Allow enabling DOE without CXL
PCI/DOE: Expose DOE features via sysfs
PCI/DOE: Rename Discovery Response Data Object Contents to type
PCI/DOE: Rename DOE protocol to feature
Per PCIe r6.0, sec 7.8.6.2, devices can advertise Resizable BAR sizes up to
128 TB in the Resizable BAR Capability register. Larger sizes can be
advertised via the Capability register, but that requires an API change.
Update pci_rebar_get_possible_sizes() and pbus_size_mem() to increase the
sizes we currently support from 512 GB to 128 TB.
Link: https://lore.kernel.org/r/20250307053535.44918-1-daizhiyuan@phytium.com.cn
Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
PCIe r6.1, sec 6.30.1.1, describes a "Vendor ID", a "Data Object Type" and
"Next Index" as the fields in the DOE Discovery Response Data Object. The
DOE driver currently uses both the terms 'type' and 'prot' for the second
element.
Rename all uses of the DOE Discovery Response Data Object to use 'type' as
the second element of the object header, instead of type/prot as it
currently is.
Link: https://lore.kernel.org/r/20250306075211.1855177-2-alistair@alistair23.me
Signed-off-by: Alistair Francis <alistair@alistair23.me>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Flit mode introduced in PCIe r6.0 alters how the TLP Header Log is
presented through AER and DPC Capability registers. The TLP Prefix Log
Register is not present with Flit mode, and the register becomes an
extension of the TLP Header Log (PCIe r6.1 secs 7.8.4.12 & 7.9.14.13).
Adapt pcie_read_tlp_log() and struct pcie_tlp_log to read and store the
extended TLP Header Log when the Link is in Flit mode. As the Prefix Log
and Extended TLP Header are not present at the same time, a C union can be
used.
Determining whether the error occurred while the Link was in Flit mode is a
bit complicated. In case of AER, the Advanced Error Capabilities and
Control Register directly tells whether the error was logged in Flit mode
or not (PCIe r6.1 sec 7.8.4.7). The DPC Capability (PCIe r6.1 sec 7.9.14),
unfortunately, does not contain the same information.
Unlike AER, the DPC Capability does not provide a way to discern whether
the error was logged in Flit mode (this is confirmed by PCI WG to be an
oversight in the spec). DPC will bring the Link down immediately following
an error, which makes it impossible to acquire the Flit Mode Status
directly from the Link Status 2 register because Flit Mode Status is only
set in certain Link states (PCIe r6.1 sec 7.5.3.20). As a workaround, use
the flit_mode value stored into the struct pci_bus.
Link: https://lore.kernel.org/r/20250207161836.2755-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Remove duplicate macro PCI_VSEC_HDR and its related macro
PCI_VSEC_HDR_LEN_SHIFT from pci_regs.h to avoid redundancy and
inconsistencies. Update VFIO PCI code to use PCI_VNDR_HEADER and
PCI_VNDR_HEADER_LEN() for consistent naming and functionality.
These changes aim to streamline header handling while minimizing impact,
given the niche usage of these macros in userspace.
Link: https://lore.kernel.org/r/20241216013536.4487-1-zhangdongdong@eswincomputing.com
Signed-off-by: Dongdong Zhang <zhangdongdong@eswincomputing.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
pcie_read_tlp_log() handles only 4 Header Log DWORDs but TLP Prefix Log
(PCIe r6.1 secs 7.8.4.12 & 7.9.14.13) may also be present.
Generalize pcie_read_tlp_log() and struct pcie_tlp_log to also handle TLP
Prefix Log. The relevant registers are formatted identically in AER and DPC
Capability, but has these variations:
a) The offsets of TLP Prefix Log registers vary.
b) DPC RP PIO TLP Prefix Log register can be < 4 DWORDs.
c) AER TLP Prefix Log Present (PCIe r6.1 sec 7.8.4.7) can indicate Prefix
Log is not present.
Therefore callers must pass the offset of the TLP Prefix Log register and
the entire length to pcie_read_tlp_log() to be able to read the correct
number of TLP Prefix DWORDs from the correct offset.
Link: https://lore.kernel.org/r/20250114170840.1633-8-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
[bhelgaas: squash ternary fix from
https://lore.kernel.org/r/20250116172019.88116-1-colin.i.king@gmail.com]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
eetlp_prefix_path in the struct pci_dev tells if End-End TLP Prefixes
are supported by the path or not, and the value is only calculated if
CONFIG_PCI_PASID is set.
The Max End-End TLP Prefixes field in the Device Capabilities Register 2
also tells how many (1-4) End-End TLP Prefixes are supported (PCIe r6.2 sec
7.5.3.15). The number of supported End-End Prefixes is useful for reading
correct number of DWORDs from TLP Prefix Log register in AER capability
(PCIe r6.2 sec 7.8.4.12).
Replace eetlp_prefix_path with eetlp_prefix_max and determine the number of
supported End-End Prefixes regardless of CONFIG_PCI_PASID so that an
upcoming commit generalizing TLP Prefix Log register reading does not have
to read extra DWORDs for End-End Prefixes that never will be there.
The value stored into eetlp_prefix_max is directly derived from device's
Max End-End TLP Prefixes and does not consider limitations imposed by
bridges or the Root Port beyond supported/not supported flags. This is
intentional for two reasons:
1) PCIe r6.2 spec sections 2.2.10.4 & 6.2.4.4 indicate that a TLP is
malformed only if the number of prefixes exceed the number of Max
End-End TLP Prefixes, which seems to be the case even if the device
could never receive that many prefixes due to smaller maximum imposed
by a bridge or the Root Port. If TLP parsing is later added, this
distinction is significant in interpreting what is logged by the TLP
Prefix Log registers and the value matching to the Malformed TLP
threshold is going to be more useful.
2) TLP Prefix handling happens autonomously on a low layer and the value
in eetlp_prefix_max is not programmed anywhere by the kernel (i.e.,
there is no limiter OS can control to prevent sending more than N TLP
Prefixes).
Link: https://lore.kernel.org/r/20250114170840.1633-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Yazen Ghannam <yazen.ghannam@amd.com>
- Add and document TLP Processing Hints (TPH) support so drivers can enable
and disable TPH and the kernel can save/restore TPH configuration (Wei
Huang)
- Add TPH Steering Tag support so drivers can retrieve Steering Tag values
associated with specific CPUs via an ACPI _DSM to direct DMA writes
closer to their consumers (Wei Huang)
* pci/tph:
PCI/TPH: Add TPH documentation
PCI/TPH: Add Steering Tag support
PCI: Add TLP Processing Hints (TPH) support
Bjorn Helgaas
Linus Torvalds
Ilpo JärvinenandBjorn Helgaas
Terry BowmanandDave Jiang
Dan Williams
Lukas WunnerandBjorn Helgaas
Hans ZhangandBjorn Helgaas
Michał WiniarskiandBjorn Helgaas
Krishna Chaitanya ChundruandManivannan Sadhasivam
Zhiyuan DaiandBjorn Helgaas
Alistair FrancisandBjorn Helgaas
Dongdong ZhangandBjorn Helgaas
