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[PULL 7/8] hw/pci: add comment to explain checking for available function 0 in pci hotplug

Michael Tokarev posted 8 patches 2 years, 6 months ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Greg Kurz <groug@kaod.org>, Christian Schoenebeck <qemu_oss@crudebyte.com>, "Cédric Le Goater" <clg@kaod.org>, Peter Maydell <peter.maydell@linaro.org>, Andrew Jeffery <andrew@aj.id.au>, Joel Stanley <joel@jms.id.au>, Thomas Huth <thuth@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, David Hildenbrand <david@redhat.com>, Laurent Vivier <laurent@vivier.eu>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Beniamino Galvani <b.galvani@gmail.com>, Strahinja Jankovic <strahinja.p.jankovic@gmail.com>, Igor Mitsyanko <i.mitsyanko@gmail.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>, Andrey Smirnov <andrew.smirnov@gmail.com>, Matthew Rosato <mjrosato@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>, Juan Quintela <quintela@redhat.com>, Peter Xu <peterx@redhat.com>, Leonardo Bras <leobras@redhat.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>, Song Gao <gaosong@loongson.cn>, Xiaojuan Yang <yangxiaojuan@loongson.cn>, Stafford Horne <shorne@gmail.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Ilya Leoshkevich <iii@linux.ibm.com>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>, "Alex Bennée" <alex.bennee@linaro.org>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Eduardo Habkost <eduardo@habkost.net>
[PULL 7/8] hw/pci: add comment to explain checking for available function 0 in pci hotplug
Posted by Michael Tokarev 2 years, 6 months ago 
From: Ani Sinha <anisinha@redhat.com>

This change is cosmetic. A comment is added explaining why we need to check for
the availability of function 0 when we hotplug a device.

CC: mst@redhat.com
CC: mjt@tls.msk.ru
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
---
 hw/pci/pci.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 784c02a182..b8d22e2e74 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -1183,9 +1183,14 @@ static PCIDevice *do_pci_register_device(PCIDevice *pci_dev,
                    PCI_SLOT(devfn), PCI_FUNC(devfn), name,
                    bus->devices[devfn]->name, bus->devices[devfn]->qdev.id);
         return NULL;
-    } else if (dev->hotplugged &&
-               !pci_is_vf(pci_dev) &&
-               pci_get_function_0(pci_dev)) {
+    } /*
+       * Populating function 0 triggers a scan from the guest that
+       * exposes other non-zero functions. Hence we need to ensure that
+       * function 0 wasn't added yet.
+       */
+    else if (dev->hotplugged &&
+             !pci_is_vf(pci_dev) &&
+             pci_get_function_0(pci_dev)) {
         error_setg(errp, "PCI: slot %d function 0 already occupied by %s,"
                    " new func %s cannot be exposed to guest.",
                    PCI_SLOT(pci_get_function_0(pci_dev)->devfn),
-- 
2.39.2

Patchew 2.1-devel-b67e4c2

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