Re: SEV guest debugging support for Qemu

[Paolo Bonzini <pbonzini@redhat.com>]

On 26/09/20 01:48, Ashish Kalra wrote:
> Thanks for your input, i have one additional query with reference to this support :
> 
> For all explicitly unecrypted guest memory regions such as S/W IOTLB bounce buffers,
> dma_decrypted() allocated regions and for guest regions marked as "__bss_decrypted",
> we need to ensure that DBG_DECRYPT API calls are bypassed for such
> regions and those regions are dumped as un-encrypted.

Yes those would be a bit different as they would be physical memory
accesses.  Those currently go through address_space_read in memory_dump
(monitor/misc.c), and would have to use the MemoryDebugOps instead.
That is the place to hook into in order to read the KVM page encryption
bitmap (which is not per-CPU, so another MemoryDebugOps entry
get_phys_addr_attrs?); the MemTxAttrs can then be passed to the read
function in the MemoryDebugOps.

> This guest memory regions encryption status is found using KVM's page encryption bitmap
> support which is part of the page encryption bitmap hypercall interface of the
> KVM/QEMU SEV live migration patches.
> 
> As this additional debug support is dependent on the KVM's page encryption bitmap
> support, are there any updates on KVM SEV live migration patches ?

Sorry about that, I've been busy with QEMU.  I'll review them as soon as
possible.

Paolo