On Fri, 7 Jan 2011 16:38:35 +0100 Jan Kiszka <jan.kis...@web.de> wrote:
> Am 07.01.2011 13:40, Alexander Graf wrote: > > > > On 07.01.2011, at 13:08, Liu Yu-B13201 wrote: > > > >> > >> Hi all, > >> > >> When guest reboot, it's better to reset status by qemu, and then sync them > >> back to kvm > >> However as you know there's no BOOKE mmu emulation in qemu, > >> So that qemu cannot directly reset BOOKE TLB. > >> Moreover a lot SPR registers also cannot be reset by qemu. > >> > >> As a workaround, we need a interface that qemu can notify kvm to reset the > >> status. > >> My question is, what should the interface be? > >> Looks like there's no alike interface in other archs. > >> Should we define a ioctl command number only used by BOOKE or powerpc? > > > > Wouldn't it make more sense to just fake-implement the registers (SPRs and > > unused TLB) and sync that back on reset? You don't have to implement the > > actual mmu logic, but that keeps things at the same place at least. > > > > This is how it's done on x86, and it's the preferred way. There will > never be such things as KVM_IOCTL_RESET. > > BTW, isn't the TLB state relevant for vmsave/restore? Then it should be > made accessible for user space anyway. It'll also be helpful for debugging, and for giving Qemu more control over how the OS is loaded -- having guest memory start somewhere other than zero is useful when doing DMA without an IOMMU, and there'll have to be a TLB entry pointing up there on entry. -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
