diff options
| author | Alex Williamson <alex.williamson@redhat.com> | 2018-02-06 11:08:27 -0700 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2018-02-06 11:08:27 -0700 |
| commit | db32d0f43839627f54a1a7f8eee17baa770f52d2 (patch) | |
| tree | 6087f8376856af72ef6503f2dc6787856e23eb55 /hw/vfio/pci.c | |
| parent | a5b04f7c5380340342ad5623b34c57fe3bab9b29 (diff) | |
vfio/pci: Add option to disable GeForce quirks
These quirks are necessary for GeForce, but not for Quadro/GRID/Tesla
assignment. Leaving them enabled is fully functional and provides the
most compatibility, but due to the unique NVIDIA MSI ACK behavior[1],
it also introduces latency in re-triggering the MSI interrupt. This
overhead is typically negligible, but has been shown to adversely
affect some (very) high interrupt rate applications. This adds the
vfio-pci device option "x-no-geforce-quirks=" which can be set to
"on" to disable this additional overhead.
A follow-on optimization for GeForce might be to make use of an
ioeventfd to allow KVM to trigger an irqfd in the kernel vfio-pci
driver, avoiding the bounce through userspace to handle this device
write.
[1] Background: the NVIDIA driver has been observed to issue a write
to the MMIO mirror of PCI config space in BAR0 in order to allow the
MSI interrupt for the device to retrigger. Older reports indicated a
write of 0xff to the (read-only) MSI capability ID register, while
more recently a write of 0x0 is observed at config space offset 0x704,
non-architected, extended config space of the device (BAR0 offset
0x88704). Virtualization of this range is only required for GeForce.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'hw/vfio/pci.c')
| -rw-r--r-- | hw/vfio/pci.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index cab2aecb80..879510c046 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -3130,6 +3130,8 @@ static Property vfio_pci_dev_properties[] = { DEFINE_PROP_BOOL("x-no-kvm-intx", VFIOPCIDevice, no_kvm_intx, false), DEFINE_PROP_BOOL("x-no-kvm-msi", VFIOPCIDevice, no_kvm_msi, false), DEFINE_PROP_BOOL("x-no-kvm-msix", VFIOPCIDevice, no_kvm_msix, false), + DEFINE_PROP_BOOL("x-no-geforce-quirks", VFIOPCIDevice, + no_geforce_quirks, false), DEFINE_PROP_UINT32("x-pci-vendor-id", VFIOPCIDevice, vendor_id, PCI_ANY_ID), DEFINE_PROP_UINT32("x-pci-device-id", VFIOPCIDevice, device_id, PCI_ANY_ID), DEFINE_PROP_UINT32("x-pci-sub-vendor-id", VFIOPCIDevice, |