icount: don't adjust virtual time backwards after warp
The icount-based QEMU_CLOCK_VIRTUAL runs ahead of the RT clock at times.
When warping, it is possible it is still ahead at the end of the warp,
which causes icount adaptive mode to adjust it backward. This can result
in the machine observing time going backwards.
Prevent this by clamping adaptive adjustment to 0 at minimum.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-ID: <
20230627061406.241847-1-npiggin@gmail.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>