On Tue, 30 Jan 2018 00:46:38 -0300 Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
> Hi Alex, > > On 01/29/2018 05:23 PM, Alex Williamson wrote: > > 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 write 0xff to > > the read-only MSI capability ID register via the MMIO mirror of PCI > > config space in order for the MSI interrupt to re-trigger. This PCI > > config space mirror is virtualized in QEMU for GeForce. > > > > Signed-off-by: Alex Williamson <alex.william...@redhat.com> > > --- > > hw/vfio/pci-quirks.c | 9 ++++++--- > > hw/vfio/pci.c | 2 ++ > > hw/vfio/pci.h | 1 + > > 3 files changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c > > index 60ad5fb91a83..e5779a7ad35b 100644 > > --- a/hw/vfio/pci-quirks.c > > +++ b/hw/vfio/pci-quirks.c > > @@ -542,7 +542,8 @@ static void > > vfio_vga_probe_nvidia_3d0_quirk(VFIOPCIDevice *vdev) > > VFIOQuirk *quirk; > > VFIONvidia3d0Quirk *data; > > > > - if (!vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > + if (vdev->no_geforce_quirks || > > + !vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > Isn't it enough to check x-pci-device-id == 0x03d0 for GeForce rather > than introduce a x-no-geforce-quirks property? Hi, That's not how any of this works. x-pci-device-id is another vfio-pci option which is only used for overriding the PCI device IDs of the assigned device, so I assuming you mean vdev->device_id. However, we can lookup here: http://pci-ids.ucw.cz/read/PC/10de that vendor ID 0x10de, device ID 0x03d0 only refers to a GeForce 6150SE embedded into the nForce 430 chipset. It certainly doesn't identify all GeForce devices, each product NVIDIA ships has a different device ID. Also, the "3d0" of this function refers to a section of the VGA I/O port region for which we're inserting a quirk, not to a specific device. This quirk is only necessary when bootstrapping the VGA BIOS on an NVIDIA graphics card. Thanks, Alex > > !vdev->bars[1].region.size) { > > return; > > } > > @@ -660,7 +661,8 @@ static void vfio_probe_nvidia_bar5_quirk(VFIOPCIDevice > > *vdev, int nr) > > VFIONvidiaBAR5Quirk *bar5; > > VFIOConfigWindowQuirk *window; > > > > - if (!vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > + if (vdev->no_geforce_quirks || > > + !vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > !vdev->vga || nr != 5 || !vdev->bars[5].ioport) { > > return; > > } > > @@ -754,7 +756,8 @@ static void vfio_probe_nvidia_bar0_quirk(VFIOPCIDevice > > *vdev, int nr) > > VFIOQuirk *quirk; > > VFIOConfigMirrorQuirk *mirror; > > > > - if (!vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > + if (vdev->no_geforce_quirks || > > + !vfio_pci_is(vdev, PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) || > > !vfio_is_vga(vdev) || nr != 0) { > > return; > > } > > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c > > index 2c7129512563..6d260b92c1e1 100644 > > --- a/hw/vfio/pci.c > > +++ b/hw/vfio/pci.c > > @@ -2989,6 +2989,8 @@ 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, > > diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h > > index a8fb3b34222c..7c55087a1c44 100644 > > --- a/hw/vfio/pci.h > > +++ b/hw/vfio/pci.h > > @@ -142,6 +142,7 @@ typedef struct VFIOPCIDevice { > > bool no_kvm_intx; > > bool no_kvm_msi; > > bool no_kvm_msix; > > + bool no_geforce_quirks; > > } VFIOPCIDevice; > > > > uint32_t vfio_pci_read_config(PCIDevice *pdev, uint32_t addr, int len); > > > > >