On Sat, 29 Oct 2016 00:35:39 +0800
Xiao Guangrong <guangrong.xiao@xxxxxxxxxxxxxxx> wrote:
> _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@xxxxxxxxxxxxxxx>
> ---
> docs/specs/acpi_nvdimm.txt | 58 ++++++++++++-
> hw/acpi/nvdimm.c | 204 ++++++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 257 insertions(+), 5 deletions(-)
>
> diff --git a/docs/specs/acpi_nvdimm.txt b/docs/specs/acpi_nvdimm.txt
> index 0fdd251..4aa5e3d 100644
> --- a/docs/specs/acpi_nvdimm.txt
> +++ b/docs/specs/acpi_nvdimm.txt
> @@ -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.
Above part should go to section where 'handle' is defined, i.e. earlier in the file:
ACPI writes _DSM Input Data (based on the offset in the page):
[0x0 - 0x3]: 4 bytes, NVDIMM Device Handle, 0 is reserved for NVDIMM
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
UUID 648B9CF2-CDA1-4312-8AD9-49C4AF32BD62 is reserved for Read_FIT DSM function
(private QEMU function)
> + 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.
_FIT method uses Read_FIT function to fetch NFIT structures blob from QEMU
in 1 page sized increments which are then concatenated and returned as _FIT method result.
> +
> + 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 |
^ field, s/Byte//, s/Byte//
> + +----------+-------------+-------------+-----------------------------------+
> + | offset | 4 | 0 | the offset of FIT buffer |
offset in QEMU's NFIT structures blob to read from
> + +----------+-------------+-------------+-----------------------------------+
> +
> + Output:
> + +----------+-------------+-------------+-----------------------------------+
> + | Filed | Byte Length | Byte Offset | Description |
> + +----------+-------------+-------------+-----------------------------------+
> + | | | | return status codes |
> + | | | | 0x100 indicates fit has been |
> + | status | 4 | 0 | updated |
0x100 - error caused by NFIT update while read by _FIT wasn't completed
> + | | | | other follows Chapter 3 in DSM |
s/other follows/other codes follow/
> + | | | | Spec Rev1 |
> + +----------+-------------+-------------+-----------------------------------+
> + | fit data | Varies | 4 | FIT data |
> + | | | | |
> + +----------+-------------+-------------+-----------------------------------+
what does "Varies" mean, how would I know reading this how much data Read_FIT should read
from shared page?
> +
> + The FIT offset is maintained by the caller itself,
probably is not necessary sentence, or specify a caller (for example OSPM)
> 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).
[...]
that's all for doc part, I'll do the code part later.
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