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irqfd is a mechanism to inject a specific interrupt to a User VM using a
decoupled eventfd mechanism.
Vhost is a kernel-level virtio server which uses eventfd for interrupt
injection. To support vhost on ACRN, irqfd is introduced in HSM.
HSM provides ioctls to associate a virtual Message Signaled Interrupt
(MSI) with an eventfd. The corresponding virtual MSI will be injected
into a User VM once the eventfd got signal.
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-17-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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ioeventfd is a mechanism to register PIO/MMIO regions to trigger an
eventfd signal when written to by a User VM. ACRN userspace can register
any arbitrary I/O address with a corresponding eventfd and then pass the
eventfd to a specific end-point of interest for handling.
Vhost is a kernel-level virtio server which uses eventfd for signalling.
To support vhost on ACRN, ioeventfd is introduced in HSM.
A new I/O client dedicated to ioeventfd is associated with a User VM
during VM creation. HSM provides ioctls to associate an I/O region with
a eventfd. The I/O client signals a eventfd once its corresponding I/O
region is matched with an I/O request.
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-16-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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.
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.
An I/O client, which is 'struct acrn_ioreq_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 I/O clients. The ACRN userspace acts as the default client for
each User VM.
The state transitions of a 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.
The processing flow of I/O requests are listed as following:
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 worker to dispatch I/O requests.
d) The worker 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.
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-10-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The HSM provides hypervisor services to the ACRN userspace. While
launching a User VM, ACRN userspace needs to allocate memory and request
the ACRN Hypervisor to set up the EPT mapping for the VM.
A mapping cache is introduced for accelerating the translation between
the Service VM kernel virtual address and User VM physical address.
>From the perspective of the hypervisor, the types of GPA of User VM can be
listed as following:
1) RAM region, which is used by User VM as system ram.
2) MMIO region, which is recognized by User VM as MMIO. MMIO region is
used to be utilized for devices emulation.
Generally, User VM RAM regions mapping is set up before VM started and
is released in the User VM destruction. MMIO regions mapping may be set
and unset dynamically during User VM running.
To achieve this, ioctls ACRN_IOCTL_SET_MEMSEG and ACRN_IOCTL_UNSET_MEMSEG
are introduced in HSM.
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-9-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The VM management interfaces expose several VM operations to ACRN
userspace via ioctls. For example, creating VM, starting VM, destroying
VM and so on.
The ACRN Hypervisor needs to exchange data with the ACRN userspace
during the VM operations. HSM provides VM operation ioctls to the ACRN
userspace and communicates with the ACRN Hypervisor for VM operations
via hypercalls.
HSM maintains a list of User VM. Each User VM will be bound to an
existing file descriptor of /dev/acrn_hsm. The User VM will be
destroyed when the file descriptor is closed.
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-7-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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ACRN Hypervisor Service Module (HSM) is a kernel module in Service VM
which communicates with ACRN userspace through ioctls and talks to ACRN
Hypervisor through hypercalls.
Add a basic HSM driver which allows Service VM userspace to communicate
with ACRN. The following patches will add more ioctls, guest VM memory
mapping caching, I/O request processing, ioeventfd and irqfd into this
module. HSM exports a char device interface (/dev/acrn_hsm) to userspace.
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-6-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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