Messages in this thread | | | Date | Tue, 23 Jun 2020 17:23:26 +0200 | From | Peter Zijlstra <> | Subject | Re: Should SEV-ES #VC use IST? (Re: [PATCH] Allow RDTSC and RDTSCP from userspace) |
| |
On Tue, Jun 23, 2020 at 04:59:14PM +0200, Joerg Roedel wrote: > On Tue, Jun 23, 2020 at 04:53:44PM +0200, Peter Zijlstra wrote: > > +noinstr void idtentry_validate_ist(struct pt_regs *regs) > > +{ > > + if ((regs->sp & ~(EXCEPTION_STKSZ-1)) == > > + (_RET_IP_ & ~(EXCEPTION_STKSZ-1))) > > + die("IST stack recursion", regs, 0); > > +} > > Yes, this is a start, it doesn't cover the case where the NMI stack is > in-between, so I think you need to walk down regs->sp too.
That shouldn't be possible with the current code, I think.
> The dumpstack code already has some logic for this.
Reliability of that depends on the unwinder, I wouldn't want the guess uwinder to OOPS me by accident.
| |