Hi, On 1/5/21 11:50 PM, shuo.a....@intel.com wrote: > From: Shuo Liu <shuo.a....@intel.com> > > Add documentation on the following aspects of ACRN: > > 1) A brief introduction on the architecture of ACRN. > 2) I/O request handling in ACRN. > 3) CPUID functions of ACRN. > > To learn more about ACRN, please go to ACRN project website > https://projectacrn.org, or the documentation page > https://projectacrn.github.io/. > > Signed-off-by: Shuo Liu <shuo.a....@intel.com> > Reviewed-by: Zhi Wang <zhi.a.w...@intel.com> > Reviewed-by: Reinette Chatre <reinette.cha...@intel.com> > Reviewed-by: Borislav Petkov <b...@suse.de> > Cc: Dave Hansen <dave.han...@intel.com> > Cc: Sen Christopherson <sean.j.christopher...@intel.com> > Cc: Dan Williams <dan.j.willi...@intel.com> > Cc: Fengwei Yin <fengwei....@intel.com> > Cc: Zhi Wang <zhi.a.w...@intel.com> > Cc: Zhenyu Wang <zhen...@linux.intel.com> > Cc: Yu Wang <yu1.w...@intel.com> > Cc: Reinette Chatre <reinette.cha...@intel.com> > Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org> > Cc: Randy Dunlap <rdun...@infradead.org> > --- > Documentation/virt/acrn/cpuid.rst | 46 +++++++++++ > Documentation/virt/acrn/index.rst | 12 +++ > Documentation/virt/acrn/introduction.rst | 43 +++++++++++ > Documentation/virt/acrn/io-request.rst | 97 ++++++++++++++++++++++++ > Documentation/virt/index.rst | 1 + > MAINTAINERS | 7 ++ > 6 files changed, 206 insertions(+) > create mode 100644 Documentation/virt/acrn/cpuid.rst > create mode 100644 Documentation/virt/acrn/index.rst > create mode 100644 Documentation/virt/acrn/introduction.rst > create mode 100644 Documentation/virt/acrn/io-request.rst > > diff --git a/Documentation/virt/acrn/cpuid.rst > b/Documentation/virt/acrn/cpuid.rst > new file mode 100644 > index 000000000000..16727fc412f0 > --- /dev/null > +++ b/Documentation/virt/acrn/cpuid.rst > @@ -0,0 +1,46 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +=============== > +ACRN CPUID bits > +=============== > + > +A guest VM running on an ACRN hypervisor, can check some of its features > using
comma not needed/not wanted. > +CPUID. > + > +ACRN cpuid functions are: > + > +function: 0x40000000 > + > +returns:: > + > + eax = 0x40000010 > + ebx = 0x4e524341 > + ecx = 0x4e524341 > + edx = 0x4e524341 > + > +Note that this value in ebx, ecx and edx corresponds to the string > +"ACRNACRNACRN". The value in eax corresponds to the maximum cpuid function > +present in this leaf, and will be updated if more functions are added in the except for the 0x4000000 bit? > +future. > + > +function: define ACRN_CPUID_FEATURES (0x40000001) > + > +returns:: > + > + ebx, ecx, edx > + eax = an OR'ed group of (1 << flag) > + > +where ``flag`` is defined as below: > + > +================================= =========== > ================================ > +flag value meaning > +================================= =========== > ================================ > +ACRN_FEATURE_PRIVILEGED_VM 0 guest VM is a privileged VM > +================================= =========== > ================================ > + > +function: 0x40000010 > + > +returns:: > + > + ebx, ecx, edx > + eax = (Virtual) TSC frequency in kHz. > diff --git a/Documentation/virt/acrn/index.rst > b/Documentation/virt/acrn/index.rst > new file mode 100644 > index 000000000000..b5f793e73df5 > --- /dev/null > +++ b/Documentation/virt/acrn/index.rst > @@ -0,0 +1,12 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +=============== > +ACRN Hypervisor > +=============== > + > +.. toctree:: > + :maxdepth: 1 > + > + introduction > + io-request > + cpuid > diff --git a/Documentation/virt/acrn/introduction.rst > b/Documentation/virt/acrn/introduction.rst > new file mode 100644 > index 000000000000..f8d081bc084d > --- /dev/null > +++ b/Documentation/virt/acrn/introduction.rst > @@ -0,0 +1,43 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +ACRN Hypervisor Introduction > +============================ > + > +The ACRN Hypervisor is a Type 1 hypervisor, running directly on bare-metal > +hardware. It has a privileged management VM, called Service VM, to manage > User > +VMs and do I/O emulation. > + > +ACRN userspace is an application running in the Service VM that emulates > +devices for a User VM based on command line configurations. ACRN Hypervisor > +Service Module (HSM) is a kernel module in the Service VM which provides > +hypervisor services to the ACRN userspace. > + > +Below figure shows the architecture. > + > +:: > + > + Service VM User VM > + +----------------------------+ | +------------------+ > + | +--------------+ | | | | > + | |ACRN userspace| | | | | > + | +--------------+ | | | | > + |-----------------ioctl------| | | | ... > + |kernel space +----------+ | | | | > + | | HSM | | | | Drivers | > + | +----------+ | | | | > + +--------------------|-------+ | +------------------+ > + +---------------------hypercall----------------------------------------+ > + | ACRN Hypervisor | > + +----------------------------------------------------------------------+ > + | Hardware | > + +----------------------------------------------------------------------+ > + > +ACRN userspace allocates memory for the User VM, configures and initializes > the > +devices used by the User VM, loads the virtual bootloader, initializes the > +virtual CPU state and handles I/O request accesses from the User VM. It uses > +ioctls to communicate with the HSM. HSM implements hypervisor services by > +interacting with the ACRN Hypervisor via hypercalls. HSM exports a char > device > +interface (/dev/acrn_hsm) to userspace. > + > +The ACRN hypervisor is open for contribution from anyone. The source repo is > +available at https://github.com/projectacrn/acrn-hypervisor. > diff --git a/Documentation/virt/acrn/io-request.rst > b/Documentation/virt/acrn/io-request.rst > new file mode 100644 > index 000000000000..79022a671ea7 > --- /dev/null > +++ b/Documentation/virt/acrn/io-request.rst > @@ -0,0 +1,97 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +I/O request handling > +==================== > + > +An I/O request of a User VM, which is constructed by the hypervisor, is > +distributed by the ACRN Hypervisor Service Module to an I/O client > +corresponding to the address range of the I/O request. Details of I/O request > +handling are described in the following sections. > + > +1. I/O request > +-------------- > + > +For each User VM, there is a shared 4-KByte memory region used for I/O > requests > +communication between the hypervisor and Service VM. An I/O request is a > +256-byte structure buffer, which is 'struct acrn_io_request', that is filled > by > +an I/O handler of the hypervisor when a trapped I/O access happens in a User > +VM. ACRN userspace in the Service VM first allocates a 4-KByte page and > passes > +the GPA (Guest Physical Address) of the buffer to the hypervisor. The buffer > is > +used as an array of 16 I/O request slots with each I/O request slot being 256 > +bytes. This array is indexed by vCPU ID. > + > +2. I/O clients > +-------------- > + > +An I/O client is responsible for handling User VM I/O requests whose accessed > +GPA falls in a certain range. Multiple I/O clients can be associated with > each > +User VM. There is a special client associated with each User VM, called the > +default client, that handles all I/O requests that do not fit into the range > of > +any other clients. The ACRN userspace acts as the default client for each > User > +VM. > + > +Below illustration shows the relationship between I/O requests shared buffer, > +I/O requests and I/O clients. > + > +:: > + > + +------------------------------------------------------+ > + | Service VM | > + |+--------------------------------------------------+ | > + || +----------------------------------------+ | | > + || | shared page ACRN userspace | | | > + || | +-----------------+ +------------+ | | | > + || +----+->| acrn_io_request |<-+ default | | | | > + || | | | +-----------------+ | I/O client | | | | > + || | | | | ... | +------------+ | | | > + || | | | +-----------------+ | | | > + || | +-|--------------------------------------+ | | > + ||---|----|-----------------------------------------| | > + || | | kernel | | > + || | | +----------------------+ | | > + || | | | +-------------+ HSM | | | > + || | +--------------+ | | | | > + || | | | I/O clients | | | | > + || | | | | | | | > + || | | +-------------+ | | | > + || | +----------------------+ | | > + |+---|----------------------------------------------+ | > + +----|-------------------------------------------------+ > + | > + +----|-------------------------------------------------+ > + | +-+-----------+ | > + | | I/O handler | ACRN Hypervisor | > + | +-------------+ | > + +------------------------------------------------------+ > + > +3. I/O request state transition > +------------------------------- > + > +The state transitions of an ACRN I/O request are as follows. > + > +:: > + > + FREE -> PENDING -> PROCESSING -> COMPLETE -> FREE -> ... > + > +- FREE: this I/O request slot is empty > +- PENDING: a valid I/O request is pending in this slot > +- PROCESSING: the I/O request is being processed > +- COMPLETE: the I/O request has been processed > + > +An I/O request in COMPLETE or FREE state is owned by the hypervisor. HSM and > +ACRN userspace are in charge of processing the others. > + > +4. Processing flow of I/O requests > +------------------------------- add 3 more '-' above, please. > + > +a. The I/O handler of the hypervisor will fill an I/O request with PENDING > + state when a trapped I/O access happens in a User VM. > +b. The hypervisor makes an upcall, which is a notification interrupt, to > + the Service VM. > +c. The upcall handler schedules a tasklet to dispatch I/O requests. > +d. The tasklet looks for the PENDING I/O requests, assigns them to different > + registered clients based on the address of the I/O accesses, updates > + their state to PROCESSING, and notifies the corresponding client to > handle. > +e. The notified client handles the assigned I/O requests. > +f. The HSM updates I/O requests states to COMPLETE and notifies the > hypervisor > + of the completion via hypercalls. > diff --git a/Documentation/virt/index.rst b/Documentation/virt/index.rst > index 350f5c869b56..edea7fea95a8 100644 > --- a/Documentation/virt/index.rst > +++ b/Documentation/virt/index.rst > @@ -12,6 +12,7 @@ Linux Virtualization Support > paravirt_ops > guest-halt-polling > ne_overview > + acrn/index > > .. only:: html and subproject thanks for the docs. -- ~Randy You can't do anything without having to do something else first. -- Belefant's Law
