From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33048) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCuVV-0006Wp-WC for qemu-devel@nongnu.org; Tue, 14 Jun 2016 16:00:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bCuVT-0001nP-Hb for qemu-devel@nongnu.org; Tue, 14 Jun 2016 16:00:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33640) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bCuVT-0001n7-9p for qemu-devel@nongnu.org; Tue, 14 Jun 2016 16:00:15 -0400 Date: Tue, 14 Jun 2016 23:00:13 +0300 From: "Michael S. Tsirkin" Message-ID: <20160614230013-mutt-send-email-mst@redhat.com> References: <1465934227-16558-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1465934227-16558-1-git-send-email-mst@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL v2 31/32] docs: add NVDIMM ACPI documentation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Xiao Guangrong , Stefan Hajnoczi From: Xiao Guangrong It describes the basic concepts of NVDIMM ACPI and the interfaces between QEMU and the ACPI BIOS Signed-off-by: Xiao Guangrong Reviewed-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- docs/specs/acpi_nvdimm.txt | 132 +++++++++++++++++++++++++++++++++++++++= ++++++ 1 file changed, 132 insertions(+) create mode 100644 docs/specs/acpi_nvdimm.txt diff --git a/docs/specs/acpi_nvdimm.txt b/docs/specs/acpi_nvdimm.txt new file mode 100644 index 0000000..0fdd251 --- /dev/null +++ b/docs/specs/acpi_nvdimm.txt @@ -0,0 +1,132 @@ +QEMU<->ACPI BIOS NVDIMM interface +--------------------------------- + +QEMU supports NVDIMM via ACPI. This document describes the basic concept= s of +NVDIMM ACPI and the interface between QEMU and the ACPI BIOS. + +NVDIMM ACPI Background +---------------------- +NVDIMM is introduced in ACPI 6.0 which defines an NVDIMM root device und= er +_SB scope with a _HID of =E2=80=9CACPI0012=E2=80=9D. For each NVDIMM pre= sent or intended +to be supported by platform, platform firmware also exposes an ACPI +Namespace Device under the root device. + +The NVDIMM child devices under the NVDIMM root device are defined with _= ADR +corresponding to the NFIT device handle. The NVDIMM root device and the +NVDIMM devices can have device specific methods (_DSM) to provide additi= onal +functions specific to a particular NVDIMM implementation. + +This is an example from ACPI 6.0, a platform contains one NVDIMM: + +Scope (\_SB){ + Device (NVDR) // Root device + { + Name (_HID, =E2=80=9CACPI0012=E2=80=9D) + Method (_STA) {...} + Method (_FIT) {...} + Method (_DSM, ...) {...} + Device (NVD) + { + Name(_ADR, h) //where h is NFIT Device Handle for this NVDIMM + Method (_DSM, ...) {...} + } + } +} + +Method supported on both NVDIMM root device and NVDIMM device +_DSM (Device Specific Method) + It is a control method that enables devices to provide device specifi= c + control functions that are consumed by the device driver. + The NVDIMM DSM specification can be found at: + http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf + + Arguments: + Arg0 =E2=80=93 A Buffer containing a UUID (16 Bytes) + Arg1 =E2=80=93 An Integer containing the Revision ID (4 Bytes) + Arg2 =E2=80=93 An Integer containing the Function Index (4 Bytes) + Arg3 =E2=80=93 A package containing parameters for the function speci= fied by the + UUID, Revision ID, and Function Index + + Return Value: + If Function Index =3D 0, a Buffer containing a function index bitfiel= d. + Otherwise, the return value and type depends on the UUID, revision ID + and function index which are described in the DSM specification. + +Methods on NVDIMM ROOT Device +_FIT(Firmware Interface Table) + It evaluates to a buffer returning data in the format of a series of = NFIT + Type Structure. + + Arguments: None + + Return Value: + A Buffer containing a list of NFIT Type structure entries. + + The detailed definition of the structure can be found at ACPI 6.0: 5.= 2.25 + NVDIMM Firmware Interface Table (NFIT). + +QEMU NVDIMM Implemention +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +QEMU uses 4 bytes IO Port starting from 0x0a18 and a RAM-based memory pa= ge +for NVDIMM ACPI. + +Memory: + QEMU uses BIOS Linker/loader feature to ask BIOS to allocate a memory + page and dynamically patch its into a int32 object named "MEMA" in AC= PI. + + This page is RAM-based and it is used to transfer data between _DSM + method and QEMU. If ACPI has control, this pages is owned by ACPI whi= ch + writes _DSM input data to it, otherwise, it is owned by QEMU which + emulates _DSM access and writes the output data to it. + + 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. + [0x4 - 0x7]: 4 bytes, Revision ID, that is the Arg1 of _DSM method. + [0x8 - 0xB]: 4 bytes. Function Index, that is the Arg2 of _DSM method= . + [0xC - 0xFFF]: 4084 bytes, the Arg3 of _DSM method. + + QEMU Writes Output Data (based on the offset in the page): + [0x0 - 0x3]: 4 bytes, the length of result + [0x4 - 0xFFF]: 4092 bytes, the DSM result filled by QEMU + +IO Port 0x0a18 - 0xa1b: + ACPI writes the address of the memory page allocated by BIOS to this + port then QEMU gets the control and fills the result in the memory pa= ge. + + write Access: + [0x0a18 - 0xa1b]: 4 bytes, the address of the memory page allocated + by BIOS. + +_DSM process diagram: +--------------------- +"MEMA" indicates the address of memory page allocated by BIOS. + + +----------------------+=E2=80=89=E2=80=89 +-----------------------+ +=E2=80=89|=E2=80=89=E2=80=89 1.=E2=80=89OSPM=E2=80=89=E2=80=89 = |=E2=80=89=E2=80=89=E2=80=89=E2=80=89=E2=80=89=E2=80=89| 2. OSPM = | +=E2=80=89|=E2=80=89save _DSM input data | | write "MEMA" to |= Exit to QEMU +=E2=80=89| to the page +----->| IO port 0x0a18 +--------= ----+ +=E2=80=89| indicated by "MEMA" | | | = | +=E2=80=89+----------------------+ +-----------------------+ = | +=E2=80=89 = | +=E2=80=89 = v +=E2=80=89+------------- ----+ +-----------+ +--------------= ----+--------+ +=E2=80=89| 5 QEMU | | 4 QEMU | | 3. QEM= U | +=E2=80=89| write _DSM result | | emulate | | get _DSM inpu= t data from | + | to the page +<------+ _DSM +<-----+ the page indicated by= the | +=E2=80=89| | | | | value from th= e IO port | + +--------+-----------+ +-----------+ +----------------------= -----+ + | + | Enter Guest + | + v + +--------------------------+ +--------------+ + | 6 OSPM | | 7 OSPM | + | result size is returned | | _DSM return | + | by reading DSM +----->+ | + | result from the page | | | + +--------------------------+ +--------------+ + + _FIT implementation + ------------------- + TODO (will fill it when nvdimm hotplug is introduced) --=20 MST