In order to prevent possible garbage collection and reuse of page table
pages prior to invalidation, introduce a former allocator abstraction
that can ensure entries are held during a single traversal. This also
cleans up the abstraction and splits it out of the machine itself.
PiperOrigin-RevId: 199581636
Change-Id: I2257d5d7ffd9c36f9b7ecd42f769261baeaf115c
This is necessary to prevent races with invalidation. It is currently
possible that page tables are garbage collected while paging caches
refer to them. We must ensure that pages are held until caches can be
invalidated. This is not achieved by this goal alone, but moving locking
to outside the page tables themselves is a requisite.
PiperOrigin-RevId: 198920784
Change-Id: I66fffecd49cb14aa2e676a84a68cabfc0c8b3e9a
Previously, the vCPU FS was always correct because it relied on the
reset coming out of the switch. When that doesn't occur, for example,
using bluepill directly, the FS value can be incorrect leading to
strange corruption.
This change is necessary for a subsequent change that enforces guest
mode for page table modifications, and it may reduce test flakiness.
(The problematic path may occur in tests, but does not occur in the
actual platform.)
PiperOrigin-RevId: 198648137
Change-Id: I513910a973dd8666c9a1d18cf78990964d6a644d
This is a refactor of ring0 and ring0/pagetables that changes from
individual arguments to opts structures. This should involve no
functional changes, but sets the stage for subsequent changes.
PiperOrigin-RevId: 198627556
Change-Id: Id4460340f6a73f0c793cd879324398139cd58ae9
Especially in situations with small numbers of vCPUs, the existing
system resulted in excessive thrashing. Now, execution contexts
co-ordinate as smoothly as they can to share a small number of cores.
PiperOrigin-RevId: 197483323
Change-Id: I0afc0c5363ea9386994355baf3904bf5fe08c56c
Adin Scannell
Michael Pratt
Ian Gudger
Googler