--- /dev/null
+QEMU<->ACPI BIOS memory hotplug interface
+--------------------------------------
+
+ACPI BIOS GPE.3 handler is dedicated for notifying OS about memory hot-add
+and hot-remove events.
+
+Memory hot-plug interface (IO port 0xa00-0xa17, 1-4 byte access):
+---------------------------------------------------------------
+0xa00:
+ read access:
+ [0x0-0x3] Lo part of memory device phys address
+ [0x4-0x7] Hi part of memory device phys address
+ [0x8-0xb] Lo part of memory device size in bytes
+ [0xc-0xf] Hi part of memory device size in bytes
+ [0x10-0x13] Memory device proximity domain
+ [0x14] Memory device status fields
+ bits:
+ 0: Device is enabled and may be used by guest
+ 1: Device insert event, used to distinguish device for which
+ no device check event to OSPM was issued.
+ It's valid only when bit 1 is set.
+ 2: Device remove event, used to distinguish device for which
+ no device eject request to OSPM was issued.
+ 3-7: reserved and should be ignored by OSPM
+ [0x15-0x17] reserved
+
+ write access:
+ [0x0-0x3] Memory device slot selector, selects active memory device.
+ All following accesses to other registers in 0xa00-0xa17
+ region will read/store data from/to selected memory device.
+ [0x4-0x7] OST event code reported by OSPM
+ [0x8-0xb] OST status code reported by OSPM
+ [0xc-0x13] reserved, writes into it are ignored
+ [0x14] Memory device control fields
+ bits:
+ 0: reserved, OSPM must clear it before writing to register.
+ Due to BUG in versions prior 2.4 that field isn't cleared
+ when other fields are written. Keep it reserved and don't
+ try to reuse it.
+ 1: if set to 1 clears device insert event, set by OSPM
+ after it has emitted device check event for the
+ selected memory device
+ 2: if set to 1 clears device remove event, set by OSPM
+ after it has emitted device eject request for the
+ selected memory device
+ 3: if set to 1 initiates device eject, set by OSPM when it
+ triggers memory device removal and calls _EJ0 method
+ 4-7: reserved, OSPM must clear them before writing to register
+
+Selecting memory device slot beyond present range has no effect on platform:
+ - write accesses to memory hot-plug registers not documented above are
+ ignored
+ - read accesses to memory hot-plug registers not documented above return
+ all bits set to 1.
+
+Memory hot remove process diagram:
+----------------------------------
+ +-------------+ +-----------------------+ +------------------+
+ | 1. QEMU | | 2. QEMU | |3. QEMU |
+ | device_del +---->+ device unplug request +----->+Send SCI to guest,|
+ | | | cb | |return control to |
+ +-------------+ +-----------------------+ |management |
+ +------------------+
+
+ +---------------------------------------------------------------------+
+
+ +---------------------+ +-------------------------+
+ | OSPM: | remove event | OSPM: |
+ | send Eject Request, | | Scan memory devices |
+ | clear remove event +<-------------+ for event flags |
+ | | | |
+ +---------------------+ +-------------------------+
+ |
+ |
+ +---------v--------+ +-----------------------+
+ | Guest OS: | success | OSPM: |
+ | process Ejection +----------->+ Execute _EJ0 method, |
+ | request | | set eject bit in flags|
+ +------------------+ +-----------------------+
+ |failure |
+ v v
+ +------------------------+ +-----------------------+
+ | OSPM: | | QEMU: |
+ | set OST event & status | | call device unplug cb |
+ | fields | | |
+ +------------------------+ +-----------------------+
+ | |
+ v v
+ +------------------+ +-------------------+
+ |QEMU: | |QEMU: |
+ |Send OST QMP event| |Send device deleted|
+ | | |QMP event |
+ +------------------+ | |
+ +-------------------+
Code Review / kvmfornfv.git / blobdiff