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Bibo Mao
e33bda7ee5
On LoongArch system, IPI hw uses iocsr registers. There are one iocsr register access on IPI sending, and two iocsr access on IPI receiving for the IPI interrupt handler. In VM mode all iocsr accessing will cause VM to trap into hypervisor. So with one IPI hw notification there will be three times of trap. In this patch PV IPI is added for VM, hypercall instruction is used for IPI sender, and hypervisor will inject an SWI to the destination vcpu. During the SWI interrupt handler, only CSR.ESTAT register is written to clear irq. CSR.ESTAT register access will not trap into hypervisor, so with PV IPI supported, there is one trap with IPI sender, and no trap with IPI receiver, there is only one trap with IPI notification. Also this patch adds IPI multicast support, the method is similar with x86. With IPI multicast support, IPI notification can be sent to at most 128 vcpus at one time. It greatly reduces the times of trapping into hypervisor. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.