ProcessesGuard stops all the crosvm processes except the caller process
using SIGSTOP signal because we must guarantee that no one changes the
guest memory contents while vmm-swap out.
This is a short term solution and will be replaced with device
suspension feature later.
See the "Write back atomicity" section in go/tanooki-phase1-dd
BUG=b:215093219
TEST=cargo build --features=swap
Change-Id: Ie62a0cf537a045128c0d298e7a73d222fea96ef0
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3932497
Reviewed-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
SwapFile saves the active pages in the memory region to a file.
design document: go/tanooki-phase1-dd
BUG=b:215093219
TEST=cargo test -p swap
Change-Id: I4ce16eef36ace832d26622e44444f7549299c1e7
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3930082
Reviewed-by: David Stevens <stevensd@chromium.org>
userfaultfd enables applications to handle page faults on designated
memory area.
vmm-swap feature uses userfaultfd to catch page fault event and swap
in the guest memory from the swap file.
design document: go/tanooki-phase1-dd
BUG=b:215093219
TEST=cargo build --features=swap
Change-Id: I13ae09cd97e4215b00e5d834d4f97eb6b507b892
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3895235
Reviewed-by: David Stevens <stevensd@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
