mcastelino/qemu_qboot_acpi_pcie_shpc_hotplug.md

## qemu_qboot_acpi_pcie_shpc_hotplug.md

      
    Raw
  

              qemu_qboot_acpi_pcie_shpc_hotplug.md
            
          
    Goal

QEMU supports multiple methods to perform device hotplug.

ACPI Hotplug on pci bus 0. (pcie.0 on virt or pci.0 on pc).
SHPC Based hotplug
PCIe Native hotplug

Kernel Requirements

The following config options have to be enabled
CONFIG_HOTPLUG_PCI_PCIE=y
CONFIG_HOTPLUG_PCI=y
CONFIG_HOTPLUG_PCI=y
CONFIG_HOTPLUG_PCI_ACPI=y
CONFIG_HOTPLUG_PCI_SHPC=y

QEMU command line

Using virt here as it support all three types of hotplug
qemu-system-x86_64 \
     -bios ./qboot/bios.bin \
     -kernel ./linux/arch/x86_64/boot/bzImage -append 'console=hvc0 root=/dev/pmem0p3 rw rootfstype=ext4 data=ordered rcupdate.rcu_expedited=1 tsc=reliable no_timer_check noapictimer' \
     -device nvdimm,id=nvdimm1,memdev=bootmem -object memory-backend-file,id=bootmem,share=on,mem-path./clear.img,size=9161408512 \
     -nographic \
     -nodefaults \
     -L . \
     -net none \
     -machine virt,accel=kvm,kernel_irqchip,nvdimm \
     -smp 4 \
     -m 1024,slots=10,maxmem=16384M \
     -monitor telnet:127.0.0.1:55555,server,nowait \
     -device virtio-serial-pci,id=virtio-serial0 -device virtconsole,chardev=charconsole0,id=console0 -chardev stdio,id=charconsole0 \
     -device pcie-root-port,id=rp50,bus=pcie.0,chassis=1,addr=5.0,multifunction=on,pref64-reserve=32M \
     -device pcie-root-port,id=rp51,bus=pcie.0,chassis=2,addr=5.1 \
     -device pcie-pci-bridge,id=br0,addr=10.0 \

Based on where you hotplug the device you get different hotplug paths

Hotplug to bus 0 -> ACPI hotplug
Hotplug to pcie-pci-rbridge -> SHPC hotplug
Hotplug to the root-port -> PCIE hotplug

Test Hotplug

Connect to the qemu monitor and run this appropriate hotplug commands
    nc -N 127.0.0.1 55555

ACPI Hotplug

       device_add virtio-net-pci
       device_add vfio-pci,host=b3:00.0

SHPC pcie-pci-bridge hotplug:

      device_add virtio-net-pci,bus=br0,addr=02.0
      device_add vfio-pci,host=b3:00.0,bus=br0,addr=03.0

PCIe Native HP

      device_add virtio-net-pci,bus=rp51
      device_add vfio-pci,host=b3:00.0,bus=rp50