In some scenarios, vfio device can't do any reset in initialization process. For example: Nvswitch and GPU A100 working in Shared NVSwitch Virtualization Model. In such mode, there are two type VMs: service VM and Guest VM. The GPU devices are initialized in the following steps: 1. Service VM boot up. GPUs and Nvswitchs are passthrough to service VM. Nvidia driver and manager software will do some settings in service VM. 2. The selected GPUs are unpluged from service VM. 3. Guest VM boots up with the selected GPUs passthrough. The selected GPUs can't do any reset in step3, or they will be initialized failed in Guest VM. This patchset add a PCI sysfs interface:ignore_reset which drivers can use it to control whether to do PCI reset or not. For example: In Shared NVSwitch Virtualization Model. Hypervisor can disable PCI reset by setting ignore_reset to 1 before Gust VM booting up. Zhenguo Yao (2): PCI: Add ignore_reset sysfs interface to control whether do device reset in PCI drivers vfio-pci: Don't do device reset when ignore_reset is setting drivers/pci/pci-sysfs.c | 25 +++++++++++++++++ drivers/vfio/pci/vfio_pci_core.c | 48 ++++++++++++++++++++------------ include/linux/pci.h | 1 + 3 files changed, 56 insertions(+), 18 deletions(-) -- 2.27.0