Because the Drop method may be called across vCPUs, it is necessary to protect
the PCID database with a mutex to prevent concurrent modification. The PCID is
assigned prior to entersyscall, so it's safe to block.
PiperOrigin-RevId: 207992864
Change-Id: I8b36d55106981f51e30dcf03e12886330bb79d67
Store the new assigned pcid in p.cache[pt].
Signed-off-by: ShiruRen <renshiru2000@gmail.com>
Change-Id: I4aee4e06559e429fb5e90cb9fe28b36139e3b4b6
PiperOrigin-RevId: 207563833
We have been unnecessarily creating too many savable types implicitly.
PiperOrigin-RevId: 206334201
Change-Id: Idc5a3a14bfb7ee125c4f2bb2b1c53164e46f29a8
In order to minimize the likelihood of exit during page table
modifications, make the full set of page table functions split-safe.
This is not strictly necessary (and you may still incur splits due to
allocations from the allocator pool) but should make retries a very rare
occurance.
PiperOrigin-RevId: 200146688
Change-Id: I8fa36aa16b807beda2f0b057be60038258e8d597
Because of the KVM shadow page table implementation, modifications made
to guest page tables from host mode may not be syncronized correctly,
resulting in undefined behavior. This is a KVM bug: page table pages
should also be tracked for host modifications and resynced appropriately
(e.g. the guest could "DMA" into a page table page in theory).
However, since we can't rely on this being fixed everywhere, workaround
the issue by forcing page table modifications to be in guest mode. This
will generally be the case anyways, but now if an exit occurs during
modifications, we will re-enter and perform the modifications again.
PiperOrigin-RevId: 199587895
Change-Id: I83c20b4cf2a9f9fa56f59f34939601dd34538fb0
Instead of associating a single PCID with each set of page tables (which
will reach the maximum quickly), allow a dynamic pool for each vCPU.
This is the same way that Linux operates. We also split management of
PCIDs out of the page tables themselves for simplicity.
PiperOrigin-RevId: 199585631
Change-Id: I42f3486ada3cb2a26f623c65ac279b473ae63201
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
As of Linux 4.15 (f29810335965ac1f7bcb501ee2af5f039f792416
KVM/x86: Check input paging mode when cs.l is set), KVM validates that
LMA is set along with LME.
PiperOrigin-RevId: 195047401
Change-Id: I8b43d8f758a85b1f58ccbd747dcacd4056ef3f66
Adin Scannell
ShiruRen
Zhaozhong Ni
Ian Gudger
Michael Pratt
Googler