docs/specs/vmw_pvscsi-spec: Convert to rST

Convert the docs/specs/vmw_pvscsi-spec.txt file to rST format.
This conversion includes some minor wordsmithing of the text
to fix some grammar nits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20230927151205.70930-2-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2023-09-27 16:11:58 +01:00
parent 7c76f397fd
commit 8472cc5dbe
4 changed files with 117 additions and 92 deletions

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@ -2350,6 +2350,7 @@ S: Maintained
F: hw/net/vmxnet*
F: hw/scsi/vmw_pvscsi*
F: tests/qtest/vmxnet3-test.c
F: docs/specs/vwm_pvscsi-spec.rst
Rocker
M: Jiri Pirko <jiri@resnulli.us>

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@ -24,3 +24,4 @@ guest hardware that is specific to QEMU.
acpi_erst
sev-guest-firmware
fw_cfg
vmw_pvscsi-spec

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@ -0,0 +1,115 @@
==============================
VMWare PVSCSI Device Interface
==============================
..
Created by Dmitry Fleytman (dmitry@daynix.com), Daynix Computing LTD.
This document describes the VMWare PVSCSI device interface specification,
based on the source code of the PVSCSI Linux driver from kernel 3.0.4.
Overview
========
The interface is based on a memory area shared between hypervisor and VM.
The memory area is obtained by driver as a device IO memory resource of
``PVSCSI_MEM_SPACE_SIZE`` length.
The shared memory consists of a registers area and a rings area.
The registers area is used to raise hypervisor interrupts and issue device
commands. The rings area is used to transfer data descriptors and SCSI
commands from VM to hypervisor and to transfer messages produced by
hypervisor to VM. Data itself is transferred via virtual scatter-gather DMA.
PVSCSI Device Registers
=======================
The length of the registers area is 1 page
(``PVSCSI_MEM_SPACE_COMMAND_NUM_PAGES``). The structure of the
registers area is described by the ``PVSCSIRegOffset`` enum. There
are registers to issue device commands (with optional short data),
issue device interrupts, and control interrupt masking.
PVSCSI Device Rings
===================
There are three rings in shared memory:
Request ring (``struct PVSCSIRingReqDesc *req_ring``)
ring for OS to device requests
Completion ring (``struct PVSCSIRingCmpDesc *cmp_ring``)
ring for device request completions
Message ring (``struct PVSCSIRingMsgDesc *msg_ring``)
ring for messages from device. This ring is optional and the
guest might not configure it.
There is a control area (``struct PVSCSIRingsState *rings_state``)
used to control rings operation.
PVSCSI Device to Host Interrupts
================================
The following interrupt types are supported by the PVSCSI device:
Completion interrupts (completion ring notifications):
- ``PVSCSI_INTR_CMPL_0``
- ``PVSCSI_INTR_CMPL_1``
Message interrupts (message ring notifications):
- ``PVSCSI_INTR_MSG_0``
- ``PVSCSI_INTR_MSG_1``
Interrupts are controlled via the ``PVSCSI_REG_OFFSET_INTR_MASK``
register. If a bit is set it means the interrupt is enabled, and if
it is clear then the interrupt is disabled.
The interrupt modes supported are legacy, MSI and MSI-X.
In the case of legacy interrupts, the ``PVSCSI_REG_OFFSET_INTR_STATUS``
register is used to check which interrupt has arrived. Interrupts are
acknowledged when the corresponding bit is written to the interrupt
status register.
PVSCSI Device Operation Sequences
=================================
Startup sequence
----------------
a. Issue ``PVSCSI_CMD_ADAPTER_RESET`` command
b. Windows driver reads interrupt status register here
c. Issue ``PVSCSI_CMD_SETUP_MSG_RING`` command with no additional data,
check status and disable device messages if error returned
(Omitted if device messages disabled by driver configuration)
d. Issue ``PVSCSI_CMD_SETUP_RINGS`` command, provide rings configuration
as ``struct PVSCSICmdDescSetupRings``
e. Issue ``PVSCSI_CMD_SETUP_MSG_RING`` command again, provide
rings configuration as ``struct PVSCSICmdDescSetupMsgRing``
f. Unmask completion and message (if device messages enabled) interrupts
Shutdown sequence
-----------------
a. Mask interrupts
b. Flush request ring using ``PVSCSI_REG_OFFSET_KICK_NON_RW_IO``
c. Issue ``PVSCSI_CMD_ADAPTER_RESET`` command
Send request
------------
a. Fill next free request ring descriptor
b. Issue ``PVSCSI_REG_OFFSET_KICK_RW_IO`` for R/W operations
or ``PVSCSI_REG_OFFSET_KICK_NON_RW_IO`` for other operations
Abort command
-------------
a. Issue ``PVSCSI_CMD_ABORT_CMD`` command
Request completion processing
-----------------------------
a. Upon completion interrupt arrival process completion
and message (if enabled) rings

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@ -1,92 +0,0 @@
General Description
===================
This document describes VMWare PVSCSI device interface specification.
Created by Dmitry Fleytman (dmitry@daynix.com), Daynix Computing LTD.
Based on source code of PVSCSI Linux driver from kernel 3.0.4
PVSCSI Device Interface Overview
================================
The interface is based on memory area shared between hypervisor and VM.
Memory area is obtained by driver as device IO memory resource of
PVSCSI_MEM_SPACE_SIZE length.
The shared memory consists of registers area and rings area.
The registers area is used to raise hypervisor interrupts and issue device
commands. The rings area is used to transfer data descriptors and SCSI
commands from VM to hypervisor and to transfer messages produced by
hypervisor to VM. Data itself is transferred via virtual scatter-gather DMA.
PVSCSI Device Registers
=======================
The length of the registers area is 1 page (PVSCSI_MEM_SPACE_COMMAND_NUM_PAGES).
The structure of the registers area is described by the PVSCSIRegOffset enum.
There are registers to issue device command (with optional short data),
issue device interrupt, control interrupts masking.
PVSCSI Device Rings
===================
There are three rings in shared memory:
1. Request ring (struct PVSCSIRingReqDesc *req_ring)
- ring for OS to device requests
2. Completion ring (struct PVSCSIRingCmpDesc *cmp_ring)
- ring for device request completions
3. Message ring (struct PVSCSIRingMsgDesc *msg_ring)
- ring for messages from device.
This ring is optional and the guest might not configure it.
There is a control area (struct PVSCSIRingsState *rings_state) used to control
rings operation.
PVSCSI Device to Host Interrupts
================================
There are following interrupt types supported by PVSCSI device:
1. Completion interrupts (completion ring notifications):
PVSCSI_INTR_CMPL_0
PVSCSI_INTR_CMPL_1
2. Message interrupts (message ring notifications):
PVSCSI_INTR_MSG_0
PVSCSI_INTR_MSG_1
Interrupts are controlled via PVSCSI_REG_OFFSET_INTR_MASK register
Bit set means interrupt enabled, bit cleared - disabled
Interrupt modes supported are legacy, MSI and MSI-X
In case of legacy interrupts, register PVSCSI_REG_OFFSET_INTR_STATUS
is used to check which interrupt has arrived. Interrupts are
acknowledged when the corresponding bit is written to the interrupt
status register.
PVSCSI Device Operation Sequences
=================================
1. Startup sequence:
a. Issue PVSCSI_CMD_ADAPTER_RESET command;
aa. Windows driver reads interrupt status register here;
b. Issue PVSCSI_CMD_SETUP_MSG_RING command with no additional data,
check status and disable device messages if error returned;
(Omitted if device messages disabled by driver configuration)
c. Issue PVSCSI_CMD_SETUP_RINGS command, provide rings configuration
as struct PVSCSICmdDescSetupRings;
d. Issue PVSCSI_CMD_SETUP_MSG_RING command again, provide
rings configuration as struct PVSCSICmdDescSetupMsgRing;
e. Unmask completion and message (if device messages enabled) interrupts.
2. Shutdown sequences
a. Mask interrupts;
b. Flush request ring using PVSCSI_REG_OFFSET_KICK_NON_RW_IO;
c. Issue PVSCSI_CMD_ADAPTER_RESET command.
3. Send request
a. Fill next free request ring descriptor;
b. Issue PVSCSI_REG_OFFSET_KICK_RW_IO for R/W operations;
or PVSCSI_REG_OFFSET_KICK_NON_RW_IO for other operations.
4. Abort command
a. Issue PVSCSI_CMD_ABORT_CMD command;
5. Request completion processing
a. Upon completion interrupt arrival process completion
and message (if enabled) rings.