From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- Documentation/PCI/endpoint/pci-vntb-function.rst | 129 +++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 Documentation/PCI/endpoint/pci-vntb-function.rst (limited to 'Documentation/PCI/endpoint/pci-vntb-function.rst') diff --git a/Documentation/PCI/endpoint/pci-vntb-function.rst b/Documentation/PCI/endpoint/pci-vntb-function.rst new file mode 100644 index 000000000..0c51f53ab --- /dev/null +++ b/Documentation/PCI/endpoint/pci-vntb-function.rst @@ -0,0 +1,129 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================= +PCI vNTB Function +================= + +:Author: Frank Li + +The difference between PCI NTB function and PCI vNTB function is + +PCI NTB function need at two endpoint instances and connect HOST1 +and HOST2. + +PCI vNTB function only use one host and one endpoint(EP), use NTB +connect EP and PCI host + +.. code-block:: text + + + +------------+ +---------------------------------------+ + | | | | + +------------+ | +--------------+ + | NTB | | | NTB | + | NetDev | | | NetDev | + +------------+ | +--------------+ + | NTB | | | NTB | + | Transfer | | | Transfer | + +------------+ | +--------------+ + | | | | | + | PCI NTB | | | | + | EPF | | | | + | Driver | | | PCI Virtual | + | | +---------------+ | NTB Driver | + | | | PCI EP NTB |<------>| | + | | | FN Driver | | | + +------------+ +---------------+ +--------------+ + | | | | | | + | PCI BUS | <-----> | PCI EP BUS | | Virtual PCI | + | | PCI | | | BUS | + +------------+ +---------------+--------+--------------+ + PCI RC PCI EP + +Constructs used for Implementing vNTB +===================================== + + 1) Config Region + 2) Self Scratchpad Registers + 3) Peer Scratchpad Registers + 4) Doorbell (DB) Registers + 5) Memory Window (MW) + + +Config Region: +-------------- + +It is same as PCI NTB Function driver + +Scratchpad Registers: +--------------------- + +It is appended after Config region. + +.. code-block:: text + + + +--------------------------------------------------+ Base + | | + | | + | | + | Common Config Register | + | | + | | + | | + +-----------------------+--------------------------+ Base + span_offset + | | | + | Peer Span Space | Span Space | + | | | + | | | + +-----------------------+--------------------------+ Base + span_offset + | | | + span_count * 4 + | | | + | Span Space | Peer Span Space | + | | | + +-----------------------+--------------------------+ + Virtual PCI Pcie Endpoint + NTB Driver NTB Driver + + +Doorbell Registers: +------------------- + + Doorbell Registers are used by the hosts to interrupt each other. + +Memory Window: +-------------- + + Actual transfer of data between the two hosts will happen using the + memory window. + +Modeling Constructs: +==================== + +32-bit BARs. + +====== =============== +BAR NO CONSTRUCTS USED +====== =============== +BAR0 Config Region +BAR1 Doorbell +BAR2 Memory Window 1 +BAR3 Memory Window 2 +BAR4 Memory Window 3 +BAR5 Memory Window 4 +====== =============== + +64-bit BARs. + +====== =============================== +BAR NO CONSTRUCTS USED +====== =============================== +BAR0 Config Region + Scratchpad +BAR1 +BAR2 Doorbell +BAR3 +BAR4 Memory Window 1 +BAR5 +====== =============================== + + -- cgit v1.3.1