Revision - 94f3f2b - KVM: selftests: create alias mappings when using shared memory - origin: https://github.com/torvalds/linux

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Revision 94f3f2b31a8a9e8bd30bf6f4903ff84acc612e0e authored by Axel Rasmussen on 19 May 2021, 20:03:37 UTC, committed by Paolo Bonzini on 27 May 2021, 11:45:56 UTC

KVM: selftests: create alias mappings when using shared memory

When a memory region is added with a src_type specifying that it should
use some kind of shared memory, also create an alias mapping to the same
underlying physical pages.

And, add an API so tests can get access to these alias addresses.
Basically, for a guest physical address, let us look up the analogous
host *alias* address.

In a future commit, we'll modify the demand paging test to take
advantage of this to exercise UFFD minor faults. The idea is, we
pre-fault the underlying pages *via the alias*. When the *guest*
faults, it gets a "minor" fault (PTEs don't exist yet, but a page is
already in the page cache). Then, the userfaultfd theads can handle the
fault: they could potentially modify the underlying memory *via the
alias* if they wanted to, and then they install the PTEs and let the
guest carry on via a UFFDIO_CONTINUE ioctl.

Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Message-Id: <20210519200339.829146-9-axelrasmussen@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Tip revision: 94f3f2b31a8a9e8bd30bf6f4903ff84acc612e0e authored by Axel Rasmussen on 19 May 2021, 20:03:37 UTC
KVM: selftests: create alias mappings when using shared memory

Tip revision: 94f3f2b

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KVM: selftests: create alias mappings when using shared memory

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