Re: Should SEV-ES #VC use IST? (Re: [PATCH] Allow RDTSC and RDTSCP from userspace)
From: Joerg Roedel <hidden>
Date: 2020-06-23 12:12:44
Also in:
kvm, lkml
From: Joerg Roedel <hidden>
Date: 2020-06-23 12:12:44
Also in:
kvm, lkml
On Tue, Jun 23, 2020 at 01:50:14PM +0200, Peter Zijlstra wrote:
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.
It is not the only reason, when ES guests gain debug register support then #VC also needs to be IST, because #DB can be promoted into #VC then, and as #DB is IST for a reason, #VC needs to be too. Besides that, I am not a fan of delegating problems I already see coming to future-Joerg and future-Peter, but if at all possible deal with them now and be safe later. Regards, Joerg