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| author | Zeng Chi <zengchi@kylinos.cn> | 2026-09-21 18:24:42 +0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2026-09-22 08:36:16 -0700 |
| commit | 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d (patch) | |
| tree | 660d50d4139cb750fbde1ae3432452c20726c99d /Documentation/PCI/endpoint/pci-vntb-function.rst | |
| download | linux-stable-119e9db233ad0f4cbd4cfb9f9385a7bca378b37d.tar.gz linux-stable-119e9db233ad0f4cbd4cfb9f9385a7bca378b37d.zip | |
KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted
Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.
Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'Documentation/PCI/endpoint/pci-vntb-function.rst')
| -rw-r--r-- | Documentation/PCI/endpoint/pci-vntb-function.rst | 129 |
1 files changed, 129 insertions, 0 deletions
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 <Frank.Li@nxp.com> + +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 +====== =============================== + + |