After a kexec the logical processors and virtual processors already
exist in the hypervisor because they were created by the previous
kernel. Attempting to add them again causes either a BUG_ON or
corrupted VP state leading to MCEs in the new kernel.
Add hv_lp_exists() to probe whether an LP is already present by
calling HVCALL_GET_LOGICAL_PROCESSOR_RUN_TIME. When it succeeds the
LP exists and we skip the add-LP and create-VP loops entirely.
Also add hv_call_notify_all_processors_started() which informs the
hypervisor that all processors are online. This is required after
adding LPs (fresh boot) and is a no-op on kexec since we skip that
path.
Co-developed-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Signed-off-by: Anirudh Rayabharam <anrayabh@linux.microsoft.com>
Co-developed-by: Stanislav Kinsburskii <stanislav.kinsburskii@gmail.com>
Signed-off-by: Stanislav Kinsburskii <stanislav.kinsburskii@gmail.com>
Co-developed-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Jork Loeser <jloeser@linux.microsoft.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Prevent infinite fault loops when guests access memory regions without
proper permissions. Currently, mshv_handle_gpa_intercept() attempts to
remap pages for all faults on movable memory regions, regardless of
whether the access type is permitted. When a guest writes to a read-only
region, the remap succeeds but the region remains read-only, causing
immediate re-fault and spinning the vCPU indefinitely.
Validate intercept access type against region permissions before
attempting remaps. Reject writes to non-writable regions and executes to
non-executable regions early, returning false to let the VMM handle the
intercept appropriately.
This also closes a potential DoS vector where malicious guests could
intentionally trigger these fault loops to consume host resources.
Fixes: b9a66cd5cc ("mshv: Add support for movable memory regions")
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This reverts commit 36d6cbb621.
Calling this as a passthrough hypercall leaves the VM in an inconsistent
state. Revert before it is released.
Signed-off-by: Wei Liu <wei.liu@kernel.org>
On x86, the HYPERVISOR_CALLBACK_VECTOR is used to receive synthetic
interrupts (SINTs) from the hypervisor for doorbells and intercepts.
There is no such vector reserved for arm64.
On arm64, the hypervisor exposes a synthetic register that can be read
to find the INTID that should be used for SINTs. This INTID is in the
PPI range.
To better unify the code paths, introduce mshv_sint_vector_init() that
either reads the synthetic register and obtains the INTID (arm64) or
just uses HYPERVISOR_CALLBACK_VECTOR as the interrupt vector (x86).
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Pull Hyper-V updates from Wei Liu:
- Debugfs support for MSHV statistics (Nuno Das Neves)
- Support for the integrated scheduler (Stanislav Kinsburskii)
- Various fixes for MSHV memory management and hypervisor status
handling (Stanislav Kinsburskii)
- Expose more capabilities and flags for MSHV partition management
(Anatol Belski, Muminul Islam, Magnus Kulke)
- Miscellaneous fixes to improve code quality and stability (Carlos
López, Ethan Nelson-Moore, Li RongQing, Michael Kelley, Mukesh
Rathor, Purna Pavan Chandra Aekkaladevi, Stanislav Kinsburskii, Uros
Bizjak)
- PREEMPT_RT fixes for vmbus interrupts (Jan Kiszka)
* tag 'hyperv-next-signed-20260218' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (34 commits)
mshv: Handle insufficient root memory hypervisor statuses
mshv: Handle insufficient contiguous memory hypervisor status
mshv: Introduce hv_deposit_memory helper functions
mshv: Introduce hv_result_needs_memory() helper function
mshv: Add SMT_ENABLED_GUEST partition creation flag
mshv: Add nested virtualization creation flag
Drivers: hv: vmbus: Simplify allocation of vmbus_evt
mshv: expose the scrub partition hypercall
mshv: Add support for integrated scheduler
mshv: Use try_cmpxchg() instead of cmpxchg()
x86/hyperv: Fix error pointer dereference
x86/hyperv: Reserve 3 interrupt vectors used exclusively by MSHV
Drivers: hv: vmbus: Use kthread for vmbus interrupts on PREEMPT_RT
x86/hyperv: Remove ASM_CALL_CONSTRAINT with VMMCALL insn
x86/hyperv: Use savesegment() instead of inline asm() to save segment registers
mshv: fix SRCU protection in irqfd resampler ack handler
mshv: make field names descriptive in a header struct
x86/hyperv: Update comment in hyperv_cleanup()
mshv: clear eventfd counter on irqfd shutdown
x86/hyperv: Use memremap()/memunmap() instead of ioremap_cache()/iounmap()
...
When creating guest partition objects, the hypervisor may fail to
allocate root partition pages and return an insufficient memory status.
In this case, deposit memory using the root partition ID instead.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Reviewed-by: Mukesh R <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
The HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY status indicates that the
hypervisor lacks sufficient contiguous memory for its internal allocations.
When this status is encountered, allocate and deposit
HV_MAX_CONTIGUOUS_ALLOCATION_PAGES contiguous pages to the hypervisor.
HV_MAX_CONTIGUOUS_ALLOCATION_PAGES is defined in the hypervisor headers, a
deposit of this size will always satisfy the hypervisor's requirements.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Reviewed-by: Mukesh R <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Add support for HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST
to allow userspace VMMs to enable SMT for guest partitions.
Expose this via new MSHV_PT_BIT_SMT_ENABLED_GUEST flag in the UAPI.
Without this flag, the hypervisor schedules guest VPs incorrectly,
causing SMT unusable.
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Introduce HV_PARTITION_CREATION_FLAG_NESTED_VIRTUALIZATION_CAPABLE to
indicate support for nested virtualization during partition creation.
This enables clearer configuration and capability checks for nested
virtualization scenarios.
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Muminul Islam <muislam@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This hypercall needs to be exposed for VMMs to soft-reboot guests. It
will reset APIC and synthetic interrupt controller state, among others.
Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Query the hypervisor for integrated scheduler support and use it if
configured.
Microsoft Hypervisor originally provided two schedulers: root and core. The
root scheduler allows the root partition to schedule guest vCPUs across
physical cores, supporting both time slicing and CPU affinity (e.g., via
cgroups). In contrast, the core scheduler delegates vCPU-to-physical-core
scheduling entirely to the hypervisor.
Direct virtualization introduces a new privileged guest partition type - L1
Virtual Host (L1VH) — which can create child partitions from its own
resources. These child partitions are effectively siblings, scheduled by
the hypervisor's core scheduler. This prevents the L1VH parent from setting
affinity or time slicing for its own processes or guest VPs. While cgroups,
CFS, and cpuset controllers can still be used, their effectiveness is
unpredictable, as the core scheduler swaps vCPUs according to its own logic
(typically round-robin across all allocated physical CPUs). As a result,
the system may appear to "steal" time from the L1VH and its children.
To address this, Microsoft Hypervisor introduces the integrated scheduler.
This allows an L1VH partition to schedule its own vCPUs and those of its
guests across its "physical" cores, effectively emulating root scheduler
behavior within the L1VH, while retaining core scheduler behavior for the
rest of the system.
The integrated scheduler is controlled by the root partition and gated by
the vmm_enable_integrated_scheduler capability bit. If set, the hypervisor
supports the integrated scheduler. The L1VH partition must then check if it
is enabled by querying the corresponding extended partition property. If
this property is true, the L1VH partition must use the root scheduler
logic; otherwise, it must use the core scheduler. This requirement makes
reading VMM capabilities in L1VH partition a requirement too.
Signed-off-by: Andreea Pintilie <anpintil@microsoft.com>
Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
KVM SVM changes for 6.20
- Drop a user-triggerable WARN on nested_svm_load_cr3() failure.
- Add support for virtualizing ERAPS. Note, correct virtualization of ERAPS
relies on an upcoming, publicly announced change in the APM to reduce the
set of conditions where hardware (i.e. KVM) *must* flush the RAP.
- Ignore nSVM intercepts for instructions that are not supported according to
L1's virtual CPU model.
- Add support for expedited writes to the fast MMIO bus, a la VMX's fastpath
for EPT Misconfig.
- Don't set GIF when clearing EFER.SVME, as GIF exists independently of SVM,
and allow userspace to restore nested state with GIF=0.
- Treat exit_code as an unsigned 64-bit value through all of KVM.
- Add support for fetching SNP certificates from userspace.
- Fix a bug where KVM would use vmcb02 instead of vmcb01 when emulating VMLOAD
or VMSAVE on behalf of L2.
- Misc fixes and cleanups.
hv_stats_page belongs in hvhdk.h, move it there.
It does not require a union to access the data for different counters,
just use a single u64 array for simplicity and to match the Windows
definitions.
While at it, correct the ARM64 value for VpRootDispatchThreadBlocked.
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Acked-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Fix KVM's long-standing buggy handling of SVM's exit_code as a 32-bit
value. Per the APM and Xen commit d1bd157fbc ("Big merge the HVM
full-virtualisation abstractions.") (which is arguably more trustworthy
than KVM), offset 0x70 is a single 64-bit value:
070h 63:0 EXITCODE
Track exit_code as a single u64 to prevent reintroducing bugs where KVM
neglects to correctly set bits 63:32.
Fixes: 6aa8b732ca ("[PATCH] kvm: userspace interface")
Cc: Jim Mattson <jmattson@google.com>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20251230211347.4099600-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.
Use the new __TRAILING_OVERLAP() helper to fix the following warning:
include/hyperv/hvgdk_mini.h:581:25: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
This helper creates a union between a flexible-array member (FAM) and a
set of MEMBERS that would otherwise follow it.
This overlays the trailing MEMBER u64 gva_list[]; onto the FAM
struct hv_tlb_flush_ex::hv_vp_set.bank_contents[], while keeping
the FAM and the start of MEMBER aligned.
The static_assert() ensures this alignment remains, and it's
intentionally placed inmediately after the related structure --no
blank line in between.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Interrupt control structure (union hv_interupt_control) has different
fields when it comes to x86 vs ARM64. Bring in the correct structure
from HyperV header files and adjust the existing interrupt routing
code accordingly.
Signed-off-by: Jinank Jain <jinankjain@microsoft.com>
Signed-off-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Provide an interface for Virtual Machine Monitor like OpenVMM and its
use as OpenHCL paravisor to control VTL0 (Virtual trust Level).
Expose devices and support IOCTLs for features like VTL creation,
VTL0 memory management, context switch, making hypercalls,
mapping VTL0 address space to VTL2 userspace, getting new VMBus
messages and channel events in VTL2 etc.
Co-developed-by: Roman Kisel <romank@linux.microsoft.com>
Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Co-developed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Add data structures for hypervisor crash dump support to the hypervisor
host ABI header file. Details of their usages are in subsequent commits.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
In preparation for the subsequent crashdump patches, copy two hypercall
numbers to the guest ABI header published by Hyper-V. One to notify
hypervisor of an event that occurs in the root partition, other to ask
hypervisor to disable the hypervisor.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Introduce HVCALL_MAP_STATS_PAGE2 which provides a map location (GPFN)
to map the stats to. This hypercall is required for L1VH partitions,
depending on the hypervisor version. This uses the same check as the
state page map location; mshv_use_overlay_gpfn().
Add mshv_map_vp_state_page() helpers to use this new hypercall or the
old one depending on availability.
For unmapping, the original HVCALL_UNMAP_STATS_PAGE works for both
cases.
Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
The file contains a line that consists of the lone # symbol
followed by a newline. While that is a valid syntax as
defined by the C99+ grammar (6.10.7 "Null directive"), it
serves no apparent purpose in this case.
Remove the null preprocessor directive. No functional changes.
Fixes: e68bda71a2 ("hyperv: Add new Hyper-V headers in include/hyperv")
Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@linux.microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
