On Fri, Feb 26, 2010 at 02:26:32PM +0100, Alexander Graf wrote: > > On 26.02.2010, at 14:21, Joerg Roedel wrote: > > > On Fri, Feb 26, 2010 at 03:10:13PM +0200, Avi Kivity wrote: > >> On 02/26/2010 03:04 PM, Joerg Roedel wrote: > >>> > >>>> I'm still not convinced on this way of doing things. If it's static, > >>>> make it static. If it's dynamic, make it dynamic. Dynamically > >>>> generating a static list just sounds plain wrong to me. > >>> Stop. I had a static list in the first version of the patch. This list > >>> was fine except the fact that a developer needs to remember to update > >>> this list if the list of non-intercepted msrs is expanded. The whole > >>> reason for a dynamically built list is to take the task of maintaining > >>> the list away from the developer and remove a possible source of hard to > >>> find bugs. This is what the current approach does. > >> > >> The problem was the two lists. If you had a > >> > >> static struct svm_direct_access_msrs = { > >> u32 index; > >> bool longmode_only; > >> } direct_access_msrs = { > >> ... > >> }; > >> > >> You could generate > >> > >> static unsigned *msrpm_offsets_longmode, *msrpm_offsets_legacy; > >> > >> as well as the original bitmaps at module init, no? > > > > True for the msrs the guest always has access too. But for the lbr-msrs > > the intercept bits may change at runtime. So an addtional flag is > > required to indicate if the bits should be cleared initially. > > So the msrpm bitmap changes dynamically for each vcpu? Great, make it > fully dynamic then, changing the vcpu->arch.msrpm only from within its > vcpu context. No need for atomic ops. The msrpm_offsets table is global. But I think I will follow Avis suggestions and create a static direct_access_msrs list and generate the msrpm_offsets at module_init. This solves the problem of two independent lists too. Joerg -- 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