commit 01774004c7f7fdc9c1e8f1715f70d3b913f8d491
author Volker Rümelin <vr_qemu@t-online.de> Sat Apr 02 20:28:39 2022 +0200
committer Kevin O'Connor <kevin@koconnor.net> Mon Apr 04 17:13:00 2022 -0400
tree 9b51609d7512eb5220479d49d99a2d8399705cdc
parent d24f42b0d819ea473ae05b2f955b822d0126d901

reset: force standard PCI configuration access

After a reset of a QEMU -machine q35 guest, the PCI Express
Enhanced Configuration Mechanism is disabled and the variable
mmconfig no longer matches the configuration register PCIEXBAR
of the Q35 chipset. Until the variable mmconfig is reset to 0,
all pci_config_*() functions no longer work.

The variable mmconfig is located in one of the read-only C-F
segments. To reset it the pci_config_*() functions are needed,
but they do not work.

Replace all pci_config_*() calls with Standard PCI Configuration
Mechanism pci_ioconfig_*() calls until mmconfig is overwritten
with 0 by a fresh copy of the BIOS.

This fixes

In resume (status=0)
In 32bit resume
Attempting a hard reboot
Unable to unlock ram - bridge not found

and a reset loop with QEMU -accel tcg.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>