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ppc/pnv: Remove user-created PHB{3,4,5} devices

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On a real system with POWER{8,9,10} processors, PHBs are sub-units of
the processor, they can be deactivated by firmware but not plugged in
or out like a PCI adapter on a slot. Nevertheless, having user-created
PHBs in QEMU seemed to be a good idea for testing purposes :

 1. having a limited set of PHBs speedups boot time.
 2. it is useful to be able to mimic a partially broken topology you
    some time have to deal with during bring-up.

PowerNV is also used for distro install tests and having libvirt
support eases these tasks. libvirt prefers to run the machine with
-nodefaults to be sure not to drag unexpected devices which would need
to be defined in the domain file without being specified on the QEMU
command line. For this reason :

 3. -nodefaults should not include default PHBs

User-created PHB{3,4,5} devices satisfied all these needs but reality
proves to be a bit more complex, internally when modeling such
devices, and externally when dealing with the user interface.

Req 1. and 2. can be simply addressed differently with a machine option:
"phb-mask=<uint>", which QEMU would use to enable/disable PHB device
nodes when creating the device tree.

For Req 3., we need to make sure we are taking the right approach. It
seems that we should expose a new type of user-created PHB device, a
generic virtualized one, that libvirt would use and not one depending
on the processor revision. This needs more thinking.

For now, remove user-created PHB{3,4,5} devices. All the cleanups we
did are not lost and they will be useful for the next steps.

Fixes: 5bc67b052b ("ppc/pnv: Introduce user creatable pnv-phb4 devices")
Fixes: 1f6a88fffc ("ppc/pnv: Introduce support for user created PHB3 devices")
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20220314130514.529931-1-clg@kaod.org>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This commit is contained in:
Cédric Le Goater 2022-03-14 15:57:17 +01:00
parent 8e6f45cc3f
commit 9c10d86fee
5 changed files with 10 additions and 118 deletions
Download patch file Download diff file Expand all files Collapse all files

7
hw/pci-host/pnv_phb4_pec.c
View file

@ -120,6 +120,7 @@ static void pnv_pec_default_phb_realize(PnvPhb4PecState *pec,
PnvPHB4 *phb = PNV_PHB4(qdev_new(pecc->phb_type));
int phb_id = pnv_phb4_pec_get_phb_id(pec, stack_no);
object_property_add_child(OBJECT(pec), "phb[*]", OBJECT(phb));
object_property_set_link(OBJECT(phb), "pec", OBJECT(pec),
&error_abort);
object_property_set_int(OBJECT(phb), "chip-id", pec->chip_id,
@ -150,10 +151,8 @@ static void pnv_pec_realize(DeviceState *dev, Error **errp)
pec->num_phbs = pecc->num_phbs[pec->index];
/* Create PHBs if running with defaults */
if (defaults_enabled()) {
for (i = 0; i < pec->num_phbs; i++) {
pnv_pec_default_phb_realize(pec, i, errp);
}
for (i = 0; i < pec->num_phbs; i++) {
pnv_pec_default_phb_realize(pec, i, errp);
}
/* Initialize the XSCOM regions for the PEC registers */