On Tue, Jun 23, 2020 at 01:43:24PM +0200, Joerg Roedel wrote: > On Tue, Jun 23, 2020 at 01:14:43PM +0200, Peter Zijlstra wrote: > > On Tue, Jun 23, 2020 at 01:11:07PM +0200, Joerg Roedel wrote: > > > > The v3 patchset implements an unconditional shift of the #VC IST entry > > > in the NMI handler, before it can trigger a #VC exception. > > > > Going by that other thread -- where you said that any memory access can > > trigger a #VC, there just isn't such a guarantee. > > As I wrote in the other mail, this can only happen when SNP gets enabled > (which is follow-on work to this) and is handled by a stack recursion > check in the #VC handler. > > The reason I mentioned the #VC-anywhere case is to make it more clear > why #VC needs an IST handler.
If SNP is the sole reason #VC needs to be IST, then I'd strongly urge you to only make it IST if/when you try and make SNP happen, not before.
