On 2012-10-31 08:01, Xiao Guangrong wrote: > On 10/31/2012 02:46 PM, Jan Kiszka wrote: > >>> Please allow me to clarify it more clearly. >>> >>> The flash is ROMD device means guest can not write it, any kinds of guest write >>> access on this device can cause vmexit to kvm and return to userspace. >>> >>> We should pay more attention on it if we execute the code in ROMD since we >>> can not use ROMD as stack/page table/IDT table and all other implicitly write access. >>> Of course, if you do not use ROM as those purposes, it is okay. :) >> >> So the problem is that there is KVM code that still blindly writes to >> guest memory and does not take the memory regions' protection flag into >> account? And we cannot mark those regions read only in the host's page >> table? > > KVM has the ability to catch this kind of write access on ROMD, it is just hard to > emulate the implicitly memory access. Drop them? It is highly unlikely that they trigger the magic write-enable patterns at the right spot in a ROMD device. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux -- 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
