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fdt: Delete nodes of devices removed between boot and CAS 

We recently fixed node creation at CAS in order to support early hotplug
of devices between boot and CAS. Let's handle node removal now to support
early hot *un*plug of devices.

This is achieved by associating a generation number to each FDT received
from QEMU and tagging all nodes with this number in a "slof,from-fdt"
property. The generation number is kept in the fdt-generation# variable.
It starts at 0 for the initial boot time FDT, and it is incremented at
each subsequent CAS. All boot time nodes hence get "slof,from-fdt" == 0,
all nodes present at CAS get "slof,from-fdt" == 1 and so on in case the
guest calls CAS again. If a device gets hot unplugged before quiesce, we
hence can detect it doesn't have the right generation number and thus
delete the node from the DT. Note that this only affects nodes coming
from the FDT. Nodes created by SLOF don't have the "slof,from-fdt"
property, and therefore cannot be candidates to deletion.

Signed-off-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
This commit is contained in:
Greg Kurz 2020-02-10 14:16:09 +01:00 committed by Alexey Kardashevskiy
parent b7e579c856
commit efa56b851f
1 changed files with 72 additions and 0 deletions
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72
board-qemu/slof/fdt.fs
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@ -13,6 +13,11 @@
0 VALUE fdt-debug
TRUE VALUE fdt-cas-fix?
0 VALUE fdt-cas-pass
0 VALUE fdt-generation#
: fdt-update-from-fdt ( -- )
fdt-generation# encode-int s" slof,from-fdt" property
;
\ Bail out if no fdt
fdt-start 0 = IF -1 throw THEN
@ -198,6 +203,8 @@ fdt-check-header
decode-int dup fdt-create-dec fdt-create-enc 2drop
THEN
fdt-update-from-fdt
finish-device
;
@ -514,6 +521,9 @@ r> drop
swap ( newnode? a1 )
fdt-debug IF ." Current now: " pwd get-node ." = " . cr THEN
fdt-cas-pass 0= IF
fdt-update-from-fdt
THEN
BEGIN
fdt-next-tag dup OF_DT_END_NODE <>
WHILE
@ -584,8 +594,70 @@ r> drop
THEN
;
: alias-dev-path ( xt -- dev-path len )
link> execute decode-string 2swap 2drop
;
: alias-name ( xt -- alias-name len )
link> >name name>string
;
: fdt-cas-alias-obsolete? ( xt -- true|false )
alias-dev-path find-node 0=
;
: (fdt-cas-delete-obsolete-aliases) ( xt -- )
dup IF
dup @
recurse
dup alias-name s" name" str= IF ELSE
dup fdt-cas-alias-obsolete? IF
fdt-debug IF ." Deleting obsolete alias: " dup alias-name type ." -> " dup alias-dev-path type cr THEN
dup alias-name
delete-property
THEN
THEN
THEN
drop
;
: fdt-cas-delete-obsolete-aliases ( -- )
s" /aliases" find-device
get-node node>properties @ cell+ @ (fdt-cas-delete-obsolete-aliases)
device-end
;
: fdt-cas-node-obsolete? ( node -- true|false)
s" slof,from-fdt" rot get-package-property IF
\ Not a QEMU originated node
false
ELSE
decode-int nip nip fdt-generation# <
THEN
;
: (fdt-cas-search-obsolete-nodes) ( start node -- )
dup IF
dup child 2 pick swap recurse
dup peer 2 pick swap recurse
dup fdt-cas-node-obsolete? IF
fdt-debug IF dup ." Deleting obsolete node: " dup .node ." = " . cr THEN
dup delete-node
THEN
THEN
2drop
;
: fdt-cas-delete-obsolete-nodes ( start -- )
s" /" find-device get-node (fdt-cas-search-obsolete-nodes)
fdt-cas-delete-obsolete-aliases
;
: fdt-fix-cas-node ( start -- )
fdt-generation# 1+ to fdt-generation#
0 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Add phandles
dup fdt-cas-delete-obsolete-nodes \ Delete removed devices
1 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Patch+add other properties
2 to fdt-cas-pass dup (fdt-fix-cas-node) drop \ Delete phandles from pass 0
drop