* kvm-arm64/pkvm-protected-guest: (41 commits)
: .
: pKVM support for protected guests, implementing the very long
: awaited support for anonymous memory, as the elusive guestmem
: has failed to deliver on its promises despite a multi-year
: effort. Patches courtesy of Will Deacon. From the initial cover
: letter:
:
: "[...] this patch series implements support for protected guest
: memory with pKVM, where pages are unmapped from the host as they are
: faulted into the guest and can be shared back from the guest using pKVM
: hypercalls. Protected guests are created using a new machine type
: identifier and can be booted to a shell using the kvmtool patches
: available at [2], which finally means that we are able to test the pVM
: logic in pKVM. Since this is an incremental step towards full isolation
: from the host (for example, the CPU register state and DMA accesses are
: not yet isolated), creating a pVM requires a developer Kconfig option to
: be enabled in addition to booting with 'kvm-arm.mode=protected' and
: results in a kernel taint."
: .
KVM: arm64: Don't hold 'vm_table_lock' across guest page reclaim
KVM: arm64: Allow get_pkvm_hyp_vm() to take a reference to a dying VM
KVM: arm64: Prevent teardown finalisation of referenced 'hyp_vm'
drivers/virt: pkvm: Add Kconfig dependency on DMA_RESTRICTED_POOL
KVM: arm64: Rename PKVM_PAGE_STATE_MASK
KVM: arm64: Extend pKVM page ownership selftests to cover guest hvcs
KVM: arm64: Extend pKVM page ownership selftests to cover forced reclaim
KVM: arm64: Register 'selftest_vm' in the VM table
KVM: arm64: Extend pKVM page ownership selftests to cover guest donation
KVM: arm64: Add some initial documentation for pKVM
KVM: arm64: Allow userspace to create protected VMs when pKVM is enabled
KVM: arm64: Implement the MEM_UNSHARE hypercall for protected VMs
KVM: arm64: Implement the MEM_SHARE hypercall for protected VMs
KVM: arm64: Add hvc handler at EL2 for hypercalls from protected VMs
KVM: arm64: Return -EFAULT from VCPU_RUN on access to a poisoned pte
KVM: arm64: Reclaim faulting page from pKVM in spurious fault handler
KVM: arm64: Introduce hypercall to force reclaim of a protected page
KVM: arm64: Annotate guest donations with handle and gfn in host stage-2
KVM: arm64: Change 'pkvm_handle_t' to u16
KVM: arm64: Introduce host_stage2_set_owner_metadata_locked()
...
Signed-off-by: Marc Zyngier <maz@kernel.org>
If a protected vCPU faults on an IPA which appears to be mapped, query
the hypervisor to determine whether or not the faulting pte has been
poisoned by a forceful reclaim. If the pte has been poisoned, return
-EFAULT back to userspace rather than retrying the instruction forever.
Tested-by: Fuad Tabba <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-28-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Introduce a new hypercall, __pkvm_force_reclaim_guest_page(), to allow
the host to forcefully reclaim a physical page that was previous donated
to a protected guest. This results in the page being zeroed and the
previous guest mapping being poisoned so that new pages cannot be
subsequently donated at the same IPA.
Tested-by: Fuad Tabba <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-26-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
To enable reclaim of pages from a protected VM during teardown,
introduce a new hypercall to reclaim a single page from a protected
guest that is in the dying state.
Since the EL2 code is non-preemptible, the new hypercall deliberately
acts on a single page at a time so as to allow EL1 to reschedule
frequently during the teardown operation.
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Co-developed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-16-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Knowing the number of CPUs is necessary for determining the boundaries
of per-cpu variables, which will be used for upcoming hypervisor
tracing. hyp_nr_cpus which stores this value, is only initialised for
the pKVM hypervisor. Make it accessible for the nVHE hypervisor as well.
With the kernel now responsible for initialising hyp_nr_cpus, the
nr_cpus parameter is no longer needed in __pkvm_init.
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Link: https://patch.msgid.link/20260309162516.2623589-22-vdonnefort@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
We have recently found a bug [1] in the pKVM memory ownership
transitions by code inspection, but it could have been caught with a
test.
Introduce a boot-time selftest exercising all the known pKVM memory
transitions and importantly checks the rejection of illegal transitions.
The new test is hidden behind a new Kconfig option separate from
CONFIG_EL2_NVHE_DEBUG on purpose as that has side effects on the
transition checks ([1] doesn't reproduce with EL2 debug enabled).
[1] https://lore.kernel.org/kvmarm/20241128154406.602875-1-qperret@google.com/
Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250416160900.3078417-4-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
The 'concrete' (a.k.a non-meta) page states are currently encoded using
software bits in PTEs. For performance reasons, the abstract
pkvm_page_state enum uses the same bits to encode these states as that
makes conversions from and to PTEs easy.
In order to prepare the ground for moving the 'concrete' state storage
to the hyp vmemmap, re-arrange the enum to use bits 0 and 1 for this
purpose.
No functional changes intended.
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-2-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
Rather than relying on the host to free the previously-donated pKVM
hypervisor VM pages explicitly on teardown, introduce a dedicated
teardown memcache which allows the host to reclaim guest memory
resources without having to keep track of all of the allocations made by
the pKVM hypervisor at EL2.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Co-developed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
[maz: dropped __maybe_unused from unmap_donated_memory_noclear()]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-21-will@kernel.org
The host at EL1 and the pKVM hypervisor at EL2 will soon need to
exchange memory pages dynamically for creating and destroying VM state.
Indeed, the hypervisor will rely on the host to donate memory pages it
can use to create guest stage-2 page-tables and to store VM and vCPU
metadata. In order to ease this process, introduce a
'struct hyp_memcache' which is essentially a linked list of available
pages, indexed by physical addresses so that it can be passed
meaningfully between the different virtual address spaces configured at
EL1 and EL2.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-18-will@kernel.org
Mapping pages in a guest page-table from within the pKVM hypervisor at
EL2 may require cache maintenance to ensure that the initialised page
contents is visible even to non-cacheable (e.g. MMU-off) accesses from
the guest.
In preparation for performing this maintenance at EL2, introduce a
per-vCPU fixmap which allows the pKVM hypervisor to map guest pages
temporarily into its stage-1 page-table for the purposes of cache
maintenance and, in future, poisoning on the reclaim path. The use of a
fixmap avoids the need for memory allocation or locking on the map()
path.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Co-developed-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-15-will@kernel.org
Introduce a global table (and lock) to track pKVM instances at EL2, and
provide hypercalls that can be used by the untrusted host to create and
destroy pKVM VMs and their vCPUs. pKVM VM/vCPU state is directly
accessible only by the trusted hypervisor (EL2).
Each pKVM VM is directly associated with an untrusted host KVM instance,
and is referenced by the host using an opaque handle. Future patches
will provide hypercalls to allow the host to initialize/set/get pKVM
VM/vCPU state using the opaque handle.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Fuad Tabba <tabba@google.com>
Co-developed-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
[maz: silence warning on unmap_donated_memory_noclear()]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-13-will@kernel.org
In preparation for introducing VM and vCPU state at EL2, rename the
existing 'struct host_kvm' and its singleton 'host_kvm' instance to
'host_mmu' so as to avoid confusion between the structure tracking the
host stage-2 MMU state and the host instance of a 'struct kvm' for a
protected guest.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-12-will@kernel.org
Add helpers allowing the hypervisor to check whether a range of pages
are currently shared by the host, and 'pin' them if so by blocking host
unshare operations until the memory has been unpinned.
This will allow the hypervisor to take references on host-provided
data-structures (e.g. 'struct kvm') with the guarantee that these pages
will remain in a stable state until the hypervisor decides to release
them, for example during guest teardown.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-9-will@kernel.org
Transferring ownership information of a memory region from one component
to another can be achieved using a "donate" operation, which results
in the previous owner losing access to the underlying pages entirely
and the new owner having exclusive access to the page.
Implement a do_donate() helper, along the same lines as do_{un,}share,
and provide this functionality for the host-{to,from}-hyp cases as this
will later be used to donate/reclaim memory pages to store VM metadata
at EL2.
In a similar manner to the sharing transitions, permission checks are
performed by the hypervisor to ensure that the component initiating the
transition really is the owner of the page and also that the completer
does not currently have a page mapped at the target address.
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Co-developed-by: Quentin Perret <qperret@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-7-will@kernel.org
The 'pkvm_component_id' enum type provides constants to refer to the
host and the hypervisor, yet this information is duplicated by the
'pkvm_hyp_id' constant.
Remove the definition of 'pkvm_hyp_id' and move the 'pkvm_component_id'
type definition to 'mem_protect.h' so that it can be used outside of
the memory protection code, for example when initialising the owner for
hypervisor-owned pages.
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-6-will@kernel.org
Introduce an unshare hypercall which can be used to unmap memory from
the hypervisor stage-1 in nVHE protected mode. This will be useful to
update the EL2 ownership state of pages during guest teardown, and
avoids keeping dangling mappings to unreferenced portions of memory.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-14-qperret@google.com
Explicitly name the combination of SW0 | SW1 as reserved in the pte and
introduce a new PKVM_NOPAGE meta-state which, although not directly
stored in the software bits of the pte, can be used to represent an
entry for which there is no underlying page. This is distinct from an
invalid pte, as stage-2 identity mappings for the host are created
lazily and so an invalid pte there is the same as a valid mapping for
the purposes of ownership information.
This state will be used for permission checking during page transitions
in later patches.
Reviewed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211215161232.1480836-9-qperret@google.com
* kvm-arm64/mmu/vmid-cleanups:
: Cleanup the stage-2 configuration by providing a single helper,
: and tidy up some of the ordering requirements for the VMID
: allocator.
KVM: arm64: Upgrade VMID accesses to {READ,WRITE}_ONCE
KVM: arm64: Unify stage-2 programming behind __load_stage2()
KVM: arm64: Move kern_hyp_va() usage in __load_guest_stage2() into the callers
Signed-off-by: Marc Zyngier <maz@kernel.org>
The host kernel is currently able to change EL2 stage-1 mappings without
restrictions thanks to the __pkvm_create_mappings() hypercall. But in a
world where the host is no longer part of the TCB, this clearly poses a
problem.
To fix this, introduce a new hypercall to allow the host to share a
physical memory page with the hypervisor, and remove the
__pkvm_create_mappings() variant. The new hypercall implements
ownership and permission checks before allowing the sharing operation,
and it annotates the shared page in the hypervisor stage-1 and host
stage-2 page-tables.
Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-21-qperret@google.com
We will soon start annotating shared pages in page-tables in nVHE
protected mode. Define all the states in which a page can be (owned,
shared and owned, shared and borrowed), and provide helpers allowing to
convert this into SW bits annotations using the matching prot
attributes.
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210809152448.1810400-13-qperret@google.com
We currently maintain two separate memory pools for the host stage-2,
one for pages used in the page-table when mapping memory regions, and
the other to map MMIO regions. The former is large enough to map all of
memory with page granularity and the latter can cover an arbitrary
portion of IPA space, but allows to 'recycle' pages.
However, this split makes accounting difficult to manage as pages at
intermediate levels of the page-table may be used to map both memory and
MMIO regions. Simplify the scheme by merging both pools into one. This
means we can now hit the -ENOMEM case in the memory abort path, but
we're still guaranteed forward-progress in the worst case by unmapping
MMIO regions. On the plus side this also means we can usually map a lot
more MMIO space at once if memory ranges happen to be mapped with block
mappings.
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-5-qperret@google.com
When KVM runs in nVHE protected mode, use the host stage 2 to unmap the
hypervisor sections by marking them as owned by the hypervisor itself.
The long-term goal is to ensure the EL2 code can remain robust
regardless of the host's state, so this starts by making sure the host
cannot e.g. write to the .hyp sections directly.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-39-qperret@google.com
When KVM runs in protected nVHE mode, make use of a stage 2 page-table
to give the hypervisor some control over the host memory accesses. The
host stage 2 is created lazily using large block mappings if possible,
and will default to page mappings in absence of a better solution.
>From this point on, memory accesses from the host to protected memory
regions (e.g. not 'owned' by the host) are fatal and lead to hyp_panic().
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210319100146.1149909-36-qperret@google.com
