I read something about cache attacks like this:
Enter KSM (Kernel SamePage Merging). KSM enables the kernel to examine two or more already running programs and compare their memory. If any memory regions or pages are identical, KSM reduces multiple identical memory pages to a single page. This page is then marked copy on write. If the contents of the page is modified by a guest virtual machine virtual machine, a new page is created for that guest virtual machine. This means that cross-VM cache-timing attacks would now be possible.
I am confused about this statement:
This means that cross-VM cache-timing attacks would now be possible.
Can someone explain about this? source link