Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: Virt Call depth tracking mitigation | Date | Tue, 19 Jul 2022 23:17:12 +0200 |
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On Tue, Jul 19 2022 at 16:23, Andrew Cooper wrote: > On 19/07/2022 15:13, Thomas Gleixner wrote: >> Well, that makes the guest side "safe", but isn't a deep hypercall > 16 >> already underflowing in the hypervisor code before it returns to the >> guest? > > Yeah, but that's the hypervisor's problem to deal with, in whatever > manner it sees fit. > > And if the hypervisor is using IBeeRS then the first ret in guest > context will underflow.
I have a look tomorrow.
>>> That said, after a return from the hypervisor, Linux has no idea what >>> state the RSB is in, so the only safe course of action is to re-stuff. >> Indeed. >> >> Another proof for my claim that virt creates more problems than it >> solves. > > So how did you like debugging the gsbase crash on native hardware. :)
First of all I said it's creating more problems than it solves, which means it solves some problems.
But more important, I'm not a wimp.
Thanks,
tglx
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