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Re: [Qemu-devel] [PATCH] vfio/pci: Add option to disable GeForce quirks
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [PATCH] vfio/pci: Add option to disable GeForce quirks |
Date: |
Mon, 29 Jan 2018 21:38:03 -0700 |
On Tue, 30 Jan 2018 00:46:38 -0300
Philippe Mathieu-Daudé <address@hidden> 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 <address@hidden>
> > ---
> > 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);
> >
> >
>