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nvdimm acpi: introduce _FIT

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_FIT is required for hotplug support, guest will inquire the updated
device info from it if a hotplug event is received

As FIT buffer is not completely mapped into guest address space, so a
new function, Read FIT whose UUID is UUID
648B9CF2-CDA1-4312-8AD9-49C4AF32BD62, handle 0x10000, function index
is 0x1, is reserved by QEMU to read the piece of FIT buffer. The buffer
is concatenated before _FIT return

Refer to docs/specs/acpi-nvdimm.txt for detailed design

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Xiao Guangrong 2016-10-29 00:35:39 +08:00 • committed by Michael S. Tsirkin
parent 75b0713e18
commit 806864d9a8
2 changed files with 257 additions and 5 deletions
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58
docs/specs/acpi_nvdimm.txt
View file

@ -127,6 +127,58 @@ _DSM process diagram:
| result from the page | | |
+--------------------------+ +--------------+
_FIT implementation
-------------------
TODO (will fill it when nvdimm hotplug is introduced)
Device Handle Reservation
-------------------------
As we mentioned above, byte 0 ~ byte 3 in the DSM memory save NVDIMM device
handle. The handle is completely QEMU internal thing, the values in range
[0, 0xFFFF] indicate nvdimm device (O means nvdimm root device named NVDR),
other values are reserved by other purpose.
Current reserved handle:
0x10000 is reserved for QEMU internal DSM function called on the root
device.
QEMU internal use only _DSM function
------------------------------------
UUID, 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62, is reserved for QEMU internal
DSM function.
There is the function introduced by QEMU and only used by QEMU internal.
1) Read FIT
As we only reserved one page for NVDIMM ACPI it is impossible to map the
whole FIT data to guest's address space. This function is used by _FIT
method to read a piece of FIT data from QEMU.
Input parameters:
Arg0 – UUID {set to 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62}
Arg1 – Revision ID (set to 1)
Arg2 - Function Index, 0x1
Arg3 - A package containing a buffer whose layout is as follows:
+----------+-------------+-------------+-----------------------------------+
| Filed | Byte Length | Byte Offset | Description |
+----------+-------------+-------------+-----------------------------------+
| offset | 4 | 0 | the offset of FIT buffer |
+----------+-------------+-------------+-----------------------------------+
Output:
+----------+-------------+-------------+-----------------------------------+
| Filed | Byte Length | Byte Offset | Description |
+----------+-------------+-------------+-----------------------------------+
| | | | return status codes |
| | | | 0x100 indicates fit has been |
| status | 4 | 0 | updated |
| | | | other follows Chapter 3 in DSM |
| | | | Spec Rev1 |
+----------+-------------+-------------+-----------------------------------+
| fit data | Varies | 4 | FIT data |
| | | | |
+----------+-------------+-------------+-----------------------------------+
The FIT offset is maintained by the caller itself, current offset plugs
the length returned by the function is the next offset we should read.
When all the FIT data has been read out, zero length is returned.
If it returns 0x100, OSPM should restart to read FIT (read from offset 0
again).