Messages in this thread | | | Date | Tue, 23 Jun 2020 13:43:24 +0200 | From | Joerg Roedel <> | Subject | Re: Should SEV-ES #VC use IST? (Re: [PATCH] Allow RDTSC and RDTSCP from userspace) |
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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.
Regards,
Joerg
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