From 7047cb9155990dec1ee27b2ce65445a13ef40f00 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 13 Feb 2018 19:04:41 +0100 Subject: [PATCH 14/15] vfio/pci: Add option to disable GeForce quirks RH-Author: Alex Williamson Message-id: <20180213190441.27565.45691.stgit@gimli.home> Patchwork-id: 78998 O-Subject: [RHEL-7.5 qemu-kvm-rhev PATCH v2 1/2] vfio/pci: Add option to disable GeForce quirks Bugzilla: 1508330 RH-Acked-by: Laszlo Ersek RH-Acked-by: Auger Eric RH-Acked-by: Marcel Apfelbaum 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 (cherry picked from commit db32d0f43839627f54a1a7f8eee17baa770f52d2) Signed-off-by: Miroslav Rezanina --- 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 4199771..e875cca 100644 --- a/hw/vfio/pci-quirks.c +++ b/hw/vfio/pci-quirks.c @@ -541,7 +541,8 @@ 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) || !vdev->bars[1].region.size) { return; } @@ -659,7 +660,8 @@ 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; } @@ -753,7 +755,8 @@ 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 b3a2889..4cfb780 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -2992,6 +2992,8 @@ 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 a8366bb..ed9172d 100644 --- a/hw/vfio/pci.h +++ b/hw/vfio/pci.h @@ -143,6 +143,7 @@ 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); -- 1.8.3.1