Bug https://bugs.launchpad.net/qemu/+bug/754591 is caused because
the KVM module attempts to do a pci_save_state() before assigning
the device to a VM, expecting that the saved state will remain
valid until we release the device. This is in conflict with our
need to reset devices using PCI sysfs during a VM reset to
quiesce the device. Any calls to pci_reset_function() will
overwrite the device saved stated prior to reset, and reload and
invalidate the state after. KVM then ends up trying to restore
the state, but it's already invalid, so the device ends up with
reset values.
This series adds a mechanism to pull the saved state off into
an opaue buffer, which can be reloaded into the device at a later
point. Thanks,
Alex
---
Alex Williamson (2):
KVM: Use pci_store/load_saved_state() around VM device usage
PCI: Add interfaces to store and load the device saved state
drivers/pci/pci.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/kvm_host.h | 1
include/linux/pci.h | 3 +
virt/kvm/assigned-dev.c | 8 ++--
4 files changed, 103 insertions(+), 3 deletions(-)
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