On Thu, Jan 08, 2015 at 03:21:50PM +0000, Peter Maydell wrote: > On 8 January 2015 at 15:06, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > > On 08/01/15 13:16, Peter Maydell wrote: > >>> ASID cached VIVT icaches are also VMID tagged. It is thus impossible for > >>> stale cache lines to come with a new page. And if by synchronizing the > >>> caches you obtain a different instruction stream, it means you've > >>> restored the wrong page. > >> > >> ...is that true even if the dirty data in the dcache comes from > >> the userspace process doing DMA or writing the initial boot > >> image or whatever? > > > > We perform this on a page that is being brought in stage-2. Two cases: > > > > - This is a page is mapped for the first time: the icache should be > > invalid for this page (the guest should have invalidated it the first > > place), > > If this is the first instruction in the guest (ie we've just > (warm) reset the VM and are running the kernel as loaded into the guest > by QEMU/kvmtool) then the guest can't have invalidated the icache, > and QEMU can't do the invalidate because it doesn't have the vaddr > and VMID of the guest. > The guest must clean its icache before turning on the MMU, no? Whenever we reuse a VMID (rollover), we flush the entire icache for that vmid. -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
