From: Leonardo Garcia <lagarcia@br.ibm.com>
Signed-off-by: Leonardo Garcia <lagarcia@br.ibm.com>
---
docs/specs/ppc-spapr-hcalls.txt | 92 ++++++++++++++++++++-------------
1 file changed, 57 insertions(+), 35 deletions(-)
diff --git a/docs/specs/ppc-spapr-hcalls.txt b/docs/specs/ppc-spapr-hcalls.txt
index 93fe3da91b..c69dae535b 100644
--- a/docs/specs/ppc-spapr-hcalls.txt
+++ b/docs/specs/ppc-spapr-hcalls.txt
@@ -1,9 +1,15 @@
-When used with the "pseries" machine type, QEMU-system-ppc64 implements
-a set of hypervisor calls using a subset of the server "PAPR" specification
-(IBM internal at this point), which is also what IBM's proprietary hypervisor
-adheres too.
+sPAPR hypervisor calls
+----------------------
-The subset is selected based on the requirements of Linux as a guest.
+When used with the ``pseries`` machine type, ``qemu-system-ppc64`` implements
+a set of hypervisor calls (a.k.a. hcalls) defined in the `Linux on Power
+Architecture Reference document (LoPAR)
+<https://cdn.openpowerfoundation.org/wp-content/uploads/2020/07/LoPAR-20200812.pdf>`_.
+This document is a subset of the Power Architecture Platform Reference (PAPR+)
+specification (IBM internal only), which is what PowerVM, the IBM proprietary
+hypervisor, adheres to.
+
+The subset in LoPAR is selected based on the requirements of Linux as a guest.
In addition to those calls, we have added our own private hypervisor
calls which are mostly used as a private interface between the firmware
@@ -12,13 +18,14 @@ running in the guest and QEMU.
All those hypercalls start at hcall number 0xf000 which correspond
to an implementation specific range in PAPR.
-- H_RTAS (0xf000)
+H_RTAS (0xf000)
+^^^^^^^^^^^^^^^
-RTAS is a set of runtime services generally provided by the firmware
-inside the guest to the operating system. It predates the existence
-of hypervisors (it was originally an extension to Open Firmware) and
-is still used by PAPR to provide various services that aren't performance
-sensitive.
+RTAS stands for Run-Time Abstraction Sercies and is a set of runtime services
+generally provided by the firmware inside the guest to the operating system. It
+predates the existence of hypervisors (it was originally an extension to Open
+Firmware) and is still used by PAPR and LoPAR to provide various services that
+are not performance sensitive.
We currently implement the RTAS services in QEMU itself. The actual RTAS
"firmware" blob in the guest is a small stub of a few instructions which
@@ -26,22 +33,25 @@ calls our private H_RTAS hypervisor call to pass the RTAS
calls to QEMU.
Arguments:
- r3 : H_RTAS (0xf000)
- r4 : Guest physical address of RTAS parameter block
+ ``r3``: ``H_RTAS (0xf000)``
+
+ ``r4``: Guest physical address of RTAS parameter block.
Returns:
- H_SUCCESS : Successfully called the RTAS function (RTAS result
- will have been stored in the parameter block)
- H_PARAMETER : Unknown token
+ ``H_SUCCESS``: Successfully called the RTAS function (RTAS result will have
+ been stored in the parameter block).
-- H_LOGICAL_MEMOP (0xf001)
+ ``H_PARAMETER``: Unknown token.
-When the guest runs in "real mode" (in powerpc lingua this means
-with MMU disabled, ie guest effective == guest physical), it only
-has access to a subset of memory and no IOs.
+H_LOGICAL_MEMOP (0xf001)
+^^^^^^^^^^^^^^^^^^^^^^^^
-PAPR provides a set of hypervisor calls to perform cacheable or
+When the guest runs in "real mode" (in powerpc lingua this means with MMU
+disabled, i.e. guest effective address equals to guest physical address), it
+only has access to a subset of memory and no I/Os.
+
+PAPR and LoPAR provides a set of hypervisor calls to perform cacheable or
non-cacheable accesses to any guest physical addresses that the
guest can use in order to access IO devices while in real mode.
@@ -58,21 +68,33 @@ is used by our SLOF firmware to invert the screen.
Arguments:
- r3: H_LOGICAL_MEMOP (0xf001)
- r4: Guest physical address of destination
- r5: Guest physical address of source
- r6: Individual element size
- 0 = 1 byte
- 1 = 2 bytes
- 2 = 4 bytes
- 3 = 8 bytes
- r7: Number of elements
- r8: Operation
- 0 = copy
- 1 = xor
+ ``r3 ``: ``H_LOGICAL_MEMOP (0xf001)``
+
+ ``r4``: Guest physical address of destination.
+
+ ``r5``: Guest physical address of source.
+
+ ``r6``: Individual element size, defined by the binary logarithm of the
+ desired size. Supported values are:
+
+ ``0`` = 1 byte
+
+ ``1`` = 2 bytes
+
+ ``2`` = 4 bytes
+
+ ``3`` = 8 bytes
+
+ ``r7``: Number of elements.
+
+ ``r8``: Operation. Supported values are:
+
+ ``0``: copy
+
+ ``1``: xor
Returns:
- H_SUCCESS : Success
- H_PARAMETER : Invalid argument
+ ``H_SUCCESS``: Success.
+ ``H_PARAMETER``: Invalid argument.
\ No newline at end of file