|
 |
9bac43 |
From 332f7a6f8dd4ee6fae95c87e717d4527ca9344a7 Mon Sep 17 00:00:00 2001
|
|
|
9bac43 |
From: Alex Williamson <alex.williamson@redhat.com>
|
|
|
9bac43 |
Date: Tue, 13 Feb 2018 19:04:56 +0100
|
|
|
9bac43 |
Subject: [PATCH 15/15] Disable GeForce quirks in vfio-pci for RHEL machines
|
|
|
9bac43 |
|
|
|
9bac43 |
RH-Author: Alex Williamson <alex.williamson@redhat.com>
|
|
|
9bac43 |
Message-id: <20180213190456.27565.18217.stgit@gimli.home>
|
|
|
9bac43 |
Patchwork-id: 78999
|
|
|
9bac43 |
O-Subject: [RHEL-7.5 qemu-kvm-rhev PATCH v2 2/2] [RHEL] Disable GeForce quirks in vfio-pci for RHEL machines
|
|
|
9bac43 |
Bugzilla: 1508330
|
|
|
9bac43 |
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
|
|
|
9bac43 |
RH-Acked-by: Auger Eric <eric.auger@redhat.com>
|
|
|
9bac43 |
RH-Acked-by: Marcel Apfelbaum <marcel@redhat.com>
|
|
|
9bac43 |
|
|
|
9bac43 |
RHEL-ONLY - The GeForce quirks are primarily used to virtualize the
|
|
|
9bac43 |
various ways the driver and VGA BIOS has available to access PCI
|
|
|
9bac43 |
config space using alternate memory regions, ex. MMIO and I/O port.
|
|
|
9bac43 |
Generally these quirks are benign and even where not required, do not
|
|
|
9bac43 |
interfere with operation. However, NVIDIA has a strange MSI behavior
|
|
|
9bac43 |
where the MSI interrupt will not re-trigger until the driver writes
|
|
|
9bac43 |
back to specifc addresses in config space via the MMIO mirror. Since
|
|
|
9bac43 |
we virtualize the mirror for GeForce, every MSI interrupt requires an
|
|
|
9bac43 |
exit to QEMU to handle this MSI-ACK behavior. For very high interrupt
|
|
|
9bac43 |
rate applications, such as NVIDIA's DolphinVS test program, this
|
|
|
9bac43 |
virtualization causes enough overhead to degrade the performance.
|
|
|
9bac43 |
|
|
|
9bac43 |
RHEL does not support GeForce assignment and supported configurations
|
|
|
9bac43 |
using Quadro, GRID, or Tesla assignment, including NVIDIA vGPU, do not
|
|
|
9bac43 |
require these quirks. We can therefore disable these quirks by
|
|
|
9bac43 |
default, removing this overhead for supported configurations while
|
|
|
9bac43 |
still allowing unsupported configurations access to re-enable them
|
|
|
9bac43 |
via (equally unsupported) <qemu:args> options.
|
|
|
9bac43 |
|
|
|
9bac43 |
Upstream development is underway to mitigate this performance overhead
|
|
|
9bac43 |
even for GeForce, but preliminary results show that we can only
|
|
|
9bac43 |
achieve 95% of the performance of disabling the quirk entirely via an
|
|
|
9bac43 |
ioeventfd approach. Obviously detecting GeForce vs Quadro would also
|
|
|
9bac43 |
be a useful approach, but there's no clear way to do this aside from
|
|
|
9bac43 |
scraping device descriptions from libpci. Therefore, disabling
|
|
|
9bac43 |
GeForce quirks, with unsupported mechanisms to re-enable unsupported
|
|
|
9bac43 |
configurations, seems like the best approach for RHEL/RHV.
|
|
|
9bac43 |
|
|
|
9bac43 |
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
|
|
|
9bac43 |
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
|
|
|
9bac43 |
---
|
|
|
9bac43 |
include/hw/i386/pc.h | 5 +++++
|
|
|
9bac43 |
1 file changed, 5 insertions(+)
|
|
|
9bac43 |
|
|
|
9bac43 |
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
|
|
|
9bac43 |
index d1b1320..2b35ed8 100644
|
|
|
9bac43 |
--- a/include/hw/i386/pc.h
|
|
|
9bac43 |
+++ b/include/hw/i386/pc.h
|
|
|
9bac43 |
@@ -1002,6 +1002,11 @@ extern void igd_passthrough_isa_bridge_create(PCIBus *bus, uint16_t gpu_dev_id);
|
|
|
9bac43 |
.driver = TYPE_X86_CPU,\
|
|
|
9bac43 |
.property = "host-phys-bits",\
|
|
|
9bac43 |
.value = "on",\
|
|
|
9bac43 |
+ },\
|
|
|
9bac43 |
+ { /* PC_RHEL_COMPAT bz 1508330 */ \
|
|
|
9bac43 |
+ .driver = "vfio-pci",\
|
|
|
9bac43 |
+ .property = "x-no-geforce-quirks",\
|
|
|
9bac43 |
+ .value = "on",\
|
|
|
9bac43 |
},
|
|
|
9bac43 |
|
|
|
9bac43 |
#define PC_RHEL7_4_COMPAT \
|
|
|
9bac43 |
--
|
|
|
9bac43 |
1.8.3.1
|
|
|
9bac43 |
|