scftorture: Count single_rpc offline failures in statistics outputgrafted

scf_torture_stats_print() aggregates each invoker thread's counters
into a local scf_statistics structure before printing, but the
n_single_rpc_ofl field is missing from the aggregation loop.  As a
result, the "single_rpc_ofl" value printed in the statistics line is
always zero, even when smp_call_function_single() invocations for the
RPC test have failed due to offline CPUs and been counted by the
invoker threads.

Add the missing accumulation so that the printed value reflects the
actual counts.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

4 files changed, 198 insertions, 0 deletions

diff --git a/Documentation/virt/acrn/cpuid.rst b/Documentation/virt/acrn/cpuid.rst
new file mode 100644
index 000000000..65fa4b9c1
--- /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
+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
+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 000000000..b5f793e73
--- /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 000000000..f8d081bc0
--- /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 000000000..6cc3ea0fa
--- /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
+----------------------------------
+
+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.