2010-forum-Pci-express-in-qemu.pdf

PCI Express in QEmu Isaku Yamahata yamahata@private.email.ne.jp yamahata@valinux.co.jp VA Linux Systems Japan K.K. KVM-forum 2010: August 10, 2010 Agenda ● Introduction ● Current status and future work ● Summary Introduction Why PCI Express? ● New features: enhancements as a successor ● Used as express is widely accepted in the market. ● Some device drivers require express ● They check if the device is really express ● Existing PCI device assignment isnt enough ● Hardware certification requires express ● Current PCI support is also limited PCI Express features from software point of view ● Many enhancements from PCI, for example ● MMCONFIG: larger configuration space ● Native hotplug:not ACPI based ● Native power management ● AER(Advanced Error Reporting) ● ARI(Alternative Routing ID) ● VC(Virtual Channel) ● FLR(Function Level Reset) From wikipedia Native hot plug PCI express downstream port PCI express slot PCI express upstream port PCI express downstream port PCI express slot PCI express switch Power indicator Attention indicator Attention button isnert/remove device Hot plug event handled directly by OS device driver Without ACPI event handler Interrupt on event Advanced Error Reporting(AER) downstream port Express device upstream port root port Error Message Error Interrupt ● Standardized error reporting. ● Important for RAS OS Look at error record Take recovery action Typically log it and reset the devices. PCI express extended configuration space PCI configuration space PCI configuration space 0x00 0xff PCI express extended configuration space 0x00 0xff 0xfff PCI compatible Configuration space PCI express enhanced access mechanism (ECAM) PCI express extended configuration space PCI express Extended capability PCI express Extended capability PCIe MMCONFIG MMCFG area (max 256MB) 0x0 MCFG base address 0xFFFF FFFF PCI express extended configuration space 0x0 0xff 0xffff MMIO Goal ● Enable QEmu to support PCI Ex