>>> On 09.03.18 at 15:35, <[email protected]> wrote: > On 09/03/18 14:18, Jan Beulich wrote: >> Instead of "syncing" the live value to what mmu_cr4_features has, make >> sure vCPU-s run with the value most recently loaded into %cr4, such that >> after the next VM exit we continue to run with the intended value rather >> than a possibly stale one. >> >> Signed-off-by: Jan Beulich <[email protected]> >> --- >> TBD: Is the conditional really worthwhile, i.e. is the VMWRITE perhaps >> not meaningfully more expensive than the VMREAD? > > Which bits are you worried about here? We play with %cr4 quite a bit in > PV context, but we shouldn't be changing after boot in HVM context.
See the discussion on Jürgen's series, playing with CR4.PGE. By doing what I do here, VMX and SVM will no longer behave differently in regard to CR4, which I think is quite desirable. But even beyond that it is a recipe for problems to force a control register to some fixed value. Jan _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
