Restoring a snapshot on WHPX was failing with a SMP Linux guest. khei@
noticed that WHPX has a special "internal" register called
WHvRegisterInternalActivityState. This register is not in the Hypervisor
Top Level Specification, but it does appear in the WHPX headers & MSDN
docs. Its exact function is not specified, but by experimentation we
believe it contains state critical for SMP guests to restore
successfully (they restore successfully once this register is
saved/restored). Perhaps there is some IPI or kernel side LAPIC state
that is only available via this register, and that state is only
critical for SMP guests. In any event (pun intended), we treat the
register as opaque data, and that seems to work fine.
This CL also adds another register that we previously skipped over,
WHvX64RegisterDeliverabilityNotifications. This register is how we
request an interrupt injection window from WHPX for things like PIC
interrupts. Previously we weren't saving/restoring it, and it's possible
for such a request to be pending at snapshot time, so we shouldn't be
discarding that state as it could break things.
BUG=b:297294476
TEST=snapshotted & restored an Ubuntu SMP guest successfully.
Change-Id: I65c14432c9a56388bda7edeacfa21fe1fa8951a6
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4827931
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Noah Gold <nkgold@google.com>
Reviewed-by: Elie Kheirallah <khei@google.com>
crosvm is a virtual machine monitor (VMM) based on Linux’s KVM hypervisor, with a focus on
simplicity, security, and speed. crosvm is intended to run Linux guests, originally as a security
boundary for running native applications on the ChromeOS platform. Compared to QEMU, crosvm doesn’t
emulate architectures or real hardware, instead concentrating on paravirtualized devices, such as
the virtio standard.
crosvm is currently used to run Linux/Android guests on ChromeOS devices.
For contribution, see the contributor guide. Mirror
repository is available at GitHub for your convenience, but
we don't accept bug reports or pull requests there.
faea671abe
