Messages in this thread | | | Subject | Re: [PATCH v2 2/4] mm: x86: Invoke hypercall when page encryption status is changed | From | Paolo Bonzini <> | Date | Fri, 14 May 2021 11:57:27 +0200 |
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On 14/05/21 11:05, Ashish Kalra wrote: > I absolutely agree with both of your point of view. But what's the > alternative ? > > Ideally we should fail/stop migration even if a single guest page > encryption status cannot be notified and that should be the way to > proceed in this case, the guest kernel should notify the source > userspace VMM to block/stop migration in this case. > > From a practical side, i do see Qemu's migrate_add_blocker() interface > but that looks to be a static interface and also i don't think it will > force stop an ongoing migration, is there an existing mechanism > to inform userspace VMM from kernel about blocking/stopping migration ?
On the Linux side, all you need to do is WARN and write 0 to the MIGRATION_CONTROL MSR.
QEMU can check the MSR value when migrating the CPU registers at the end, and fail migration if the MSR value is 0.
Paolo
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