rSTify ppc-spapr-uv-hcalls.txt.

Signed-off-by: Leonardo Garcia <lagarcia@br.ibm.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <243a714d3861f7539d29b02a899ffc376757d668.1642446876.git.lagarcia@br.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>

docs/specs/ppc-spapr-uv-hcalls.txt

@@ -1,76 +1,89 @@
-On PPC64 systems supporting Protected Execution Facility (PEF), system
-memory can be placed in a secured region where only an "ultravisor"
-running in firmware can provide to access it. pseries guests on such
-systems can communicate with the ultravisor (via ultracalls) to switch to a
-secure VM mode (SVM) where the guest's memory is relocated to this secured
-region, making its memory inaccessible to normal processes/guests running on
-the host.
-
-The various ultracalls/hypercalls relating to SVM mode are currently
-only documented internally, but are planned for direct inclusion into the
-public OpenPOWER version of the PAPR specification (LoPAPR/LoPAR). An internal
-ACR has been filed to reserve a hypercall number range specific to this
-use-case to avoid any future conflicts with the internally-maintained PAPR
-specification. This document summarizes some of these details as they relate
-to QEMU.
-
-== hypercalls needed by the ultravisor ==
-
-Switching to SVM mode involves a number of hcalls issued by the ultravisor
-to the hypervisor to orchestrate the movement of guest memory to secure
-memory and various other aspects SVM mode. Numbers are assigned for these
-hcalls within the reserved range 0xEF00-0xEF80. The below documents the
-hcalls relevant to QEMU.
-
-- H_TPM_COMM (0xef10)
-
-  For TPM_COMM_OP_EXECUTE operation:
-    Send a request to a TPM and receive a response, opening a new TPM session
-    if one has not already been opened.
-
-  For TPM_COMM_OP_CLOSE_SESSION operation:
-    Close the existing TPM session, if any.
-
-  Arguments:
-
-    r3 : H_TPM_COMM (0xef10)
-    r4 : TPM operation, one of:
-         TPM_COMM_OP_EXECUTE (0x1)
-         TPM_COMM_OP_CLOSE_SESSION (0x2)
-    r5 : in_buffer, guest physical address of buffer containing the request
-         - Caller may use the same address for both request and response
-    r6 : in_size, size of the in buffer
-         - Must be less than or equal to 4KB
-    r7 : out_buffer, guest physical address of buffer to store the response
-         - Caller may use the same address for both request and response
-    r8 : out_size, size of the out buffer
-         - Must be at least 4KB, as this is the maximum request/response size
-           supported by most TPM implementations, including the TPM Resource
-           Manager in the linux kernel.
-
-  Return values:
-
-    r3 : H_Success    request processed successfully
-         H_PARAMETER  invalid TPM operation
-         H_P2         in_buffer is invalid
-         H_P3         in_size is invalid
-         H_P4         out_buffer is invalid
-         H_P5         out_size is invalid
-         H_RESOURCE   problem communicating with TPM
-         H_FUNCTION   TPM access is not currently allowed/configured
-    r4 : For TPM_COMM_OP_EXECUTE, the size of the response will be stored here
-         upon success.
-
-  Use-case/notes:
-
-    SVM filesystems are encrypted using a symmetric key. This key is then
-    wrapped/encrypted using the public key of a trusted system which has the
-    private key stored in the system's TPM. An Ultravisor will use this
-    hcall to unwrap/unseal the symmetric key using the system's TPM device
-    or a TPM Resource Manager associated with the device.
-
-    The Ultravisor sets up a separate session key with the TPM in advance
-    during host system boot. All sensitive in and out values will be
-    encrypted using the session key. Though the hypervisor will see the 'in'
-    and 'out' buffers in raw form, any sensitive contents will generally be
-    encrypted using this session key.
+===================================
+Hypervisor calls and the Ultravisor
+===================================
+
+On PPC64 systems supporting Protected Execution Facility (PEF), system memory
+can be placed in a secured region where only an ultravisor running in firmware
+can provide access to. pSeries guests on such systems can communicate with
+the ultravisor (via ultracalls) to switch to a secure virtual machine (SVM) mode
+where the guest's memory is relocated to this secured region, making its memory
+inaccessible to normal processes/guests running on the host.
+
+The various ultracalls/hypercalls relating to SVM mode are currently only
+documented internally, but are planned for direct inclusion into the Linux on
+Power Architecture Reference document ([LoPAR]_). An internal ACR has been filed
+to reserve a hypercall number range specific to this use case to avoid any
+future conflicts with the IBM internally maintained Power Architecture Platform
+Reference (PAPR+) documentation specification. This document summarizes some of
+these details as they relate to QEMU.
+
+Hypercalls needed by the ultravisor
+===================================
+
+Switching to SVM mode involves a number of hcalls issued by the ultravisor to
+the hypervisor to orchestrate the movement of guest memory to secure memory and
+various other aspects of the SVM mode. Numbers are assigned for these hcalls
+within the reserved range ``0xEF00-0xEF80``. The below documents the hcalls
+relevant to QEMU.
+
+``H_TPM_COMM`` (``0xef10``)
+---------------------------
+
+SVM file systems are encrypted using a symmetric key. This key is then
+wrapped/encrypted using the public key of a trusted system which has the private
+key stored in the system's TPM. An Ultravisor will use this hcall to
+unwrap/unseal the symmetric key using the system's TPM device or a TPM Resource
+Manager associated with the device.
+
+The Ultravisor sets up a separate session key with the TPM in advance during
+host system boot. All sensitive in and out values will be encrypted using the
+session key. Though the hypervisor will see the in and out buffers in raw form,
+any sensitive contents will generally be encrypted using this session key.
+
+Arguments:
+
+  ``r3``: ``H_TPM_COMM`` (``0xef10``)
+
+  ``r4``: ``TPM`` operation, one of:
+
+    ``TPM_COMM_OP_EXECUTE`` (``0x1``): send a request to a TPM and receive a
+    response, opening a new TPM session if one has not already been opened.
+
+    ``TPM_COMM_OP_CLOSE_SESSION`` (``0x2``): close the existing TPM session, if
+    any.
+
+  ``r5``: ``in_buffer``, guest physical address of buffer containing the
+  request. Caller may use the same address for both request and response.
+
+  ``r6``: ``in_size``, size of the in buffer. Must be less than or equal to
+  4 KB.
+
+  ``r7``: ``out_buffer``, guest physical address of buffer to store the
+  response. Caller may use the same address for both request and response.
+
+  ``r8``: ``out_size``, size of the out buffer. Must be at least 4 KB, as this
+  is the maximum request/response size supported by most TPM implementations,
+  including the TPM Resource Manager in the linux kernel.
+
+Return values:
+
+  ``r3``: one of the following values:
+
+    ``H_Success``: request processed successfully.
+
+    ``H_PARAMETER``: invalid TPM operation.
+
+    ``H_P2``: ``in_buffer`` is invalid.
+
+    ``H_P3``: ``in_size`` is invalid.
+
+    ``H_P4``: ``out_buffer`` is invalid.
+
+    ``H_P5``: ``out_size`` is invalid.
+
+    ``H_RESOURCE``: problem communicating with TPM.
+
+    ``H_FUNCTION``: TPM access is not currently allowed/configured.
+
+    ``r4``: For ``TPM_COMM_OP_EXECUTE``, the size of the response will be stored
+    here upon success.