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| author | Alex Williamson | 2019-05-14 22:14:41 +0200 |
|---|---|---|
| committer | Paolo Bonzini | 2019-06-03 14:03:03 +0200 |
| commit | c87759ce876a7a0b17c2bf4f0b964bd51f0ee871 (patch) | |
| tree | 1136df9621eb962326714fa330eaad310fb8de12 /hw/misc/edu.c | |
| parent | configure: remove tpm_passthrough & tpm_emulator (diff) | |
| download | qemu-c87759ce876a7a0b17c2bf4f0b964bd51f0ee871.tar.gz qemu-c87759ce876a7a0b17c2bf4f0b964bd51f0ee871.tar.xz qemu-c87759ce876a7a0b17c2bf4f0b964bd51f0ee871.zip | |
q35: Revert to kernel irqchip
Commit b2fc91db8447 ("q35: set split kernel irqchip as default") changed
the default for the pc-q35-4.0 machine type to use split irqchip, which
turned out to have disasterous effects on vfio-pci INTx support. KVM
resampling irqfds are registered for handling these interrupts, but
these are non-functional in split irqchip mode. We can't simply test
for split irqchip in QEMU as userspace handling of this interrupt is a
significant performance regression versus KVM handling (GeForce GPUs
assigned to Windows VMs are non-functional without forcing MSI mode or
re-enabling kernel irqchip).
The resolution is to revert the change in default irqchip mode in the
pc-q35-4.1 machine and create a pc-q35-4.0.1 machine for the 4.0-stable
branch. The qemu-q35-4.0 machine type should not be used in vfio-pci
configurations for devices requiring legacy INTx support without
explicitly modifying the VM configuration to use kernel irqchip.
Link: https://bugs.launchpad.net/qemu/+bug/1826422
Fixes: b2fc91db8447 ("q35: set split kernel irqchip as default")
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Message-Id: <155786484688.13873.6037015630912983760.stgit@gimli.home>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'hw/misc/edu.c')
0 files changed, 0 insertions, 0 deletions