kernel/linux.git/Documentation/virt, branch master

Merge tag 'kvm-s390-next-7.1-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2026-04-13T17:01:15+00:00

- ESA nesting support - 4k memslots - LPSW/E fix

Merge branch kvm-arm64/pkvm-protected-guest into kvmarm-master/next

2026-04-08T11:25:39+00:00

* 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

KVM: s390: Add KVM capability for ESA mode guests

2026-04-02T13:37:02+00:00

Now that all the bits are properly addressed, provide a mechanism for testing ESA mode guests in nested configurations. Signed-off-by: Hendrik Brueckner [farman@us.ibm.com: Updated commit message] Reviewed-by: Janosch Frank Signed-off-by: Eric Farman Signed-off-by: Janosch Frank

KVM: arm64: Add some initial documentation for pKVM

2026-03-30T15:58:09+00:00

Add some initial documentation for pKVM to help people understand what is supported, the limitations of protected VMs when compared to non-protected VMs and also what is left to do. Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Tested-by: Mostafa Saleh Signed-off-by: Will Deacon Link: https://patch.msgid.link/20260330144841.26181-33-will@kernel.org Signed-off-by: Marc Zyngier

KVM: arm64: gic-v5: Communicate userspace-driveable PPIs via a UAPI

2026-03-19T18:21:29+00:00

GICv5 systems will likely not support the full set of PPIs. The presence of any virtual PPI is tied to the presence of the physical PPI. Therefore, the available PPIs will be limited by the physical host. Userspace cannot drive any PPIs that are not implemented. Moreover, it is not desirable to expose all PPIs to the guest in the first place, even if they are supported in hardware. Some devices, such as the arch timer, are implemented in KVM, and hence those PPIs shouldn't be driven by userspace, either. Provided a new UAPI: KVM_DEV_ARM_VGIC_GRP_CTRL => KVM_DEV_ARM_VGIC_USERPSPACE_PPIs This allows userspace to query which PPIs it is able to drive via KVM_IRQ_LINE. Additionally, introduce a check in kvm_vm_ioctl_irq_line() to reject any PPIs not in the userspace mask. Signed-off-by: Sascha Bischoff Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20260319154937.3619520-40-sascha.bischoff@arm.com Signed-off-by: Marc Zyngier

Documentation: KVM: Introduce documentation for VGICv5

2026-03-19T18:21:29+00:00

Now that it is possible to create a VGICv5 device, provide initial documentation for it. At this stage, there is little to document. Signed-off-by: Sascha Bischoff Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20260319154937.3619520-39-sascha.bischoff@arm.com Signed-off-by: Marc Zyngier

KVM: arm64: gic-v5: Mandate architected PPI for PMU emulation on GICv5

2026-03-19T18:21:29+00:00

Make it mandatory to use the architected PPI when running a GICv5 guest. Attempts to set anything other than the architected PPI (23) are rejected. Additionally, KVM_ARM_VCPU_PMU_V3_INIT is relaxed to no longer require KVM_ARM_VCPU_PMU_V3_IRQ to be called for GICv5-based guests. In this case, the architectued PPI is automatically used. Documentation is bumped accordingly. Signed-off-by: Sascha Bischoff Reviewed-by: Jonathan Cameron Reviewed-by: Joey Gouly Link: https://patch.msgid.link/20260319154937.3619520-33-sascha.bischoff@arm.com Signed-off-by: Marc Zyngier

KVM: arm64: gic-v5: Support GICv5 interrupts with KVM_IRQ_LINE

2026-03-19T18:21:28+00:00

Interrupts under GICv5 look quite different to those from older Arm GICs. Specifically, the type is encoded in the top bits of the interrupt ID. Extend KVM_IRQ_LINE to cope with GICv5 PPIs and SPIs. The requires subtly changing the KVM_IRQ_LINE API for GICv5 guests. For older Arm GICs, PPIs had to be in the range of 16-31, and SPIs had to be 32-1019, but this no longer holds true for GICv5. Instead, for a GICv5 guest support PPIs in the range of 0-127, and SPIs in the range 0-65535. The documentation is updated accordingly. The SPI range doesn't cover the full SPI range that a GICv5 system can potentially cope with (GICv5 provides up to 24-bits of SPI ID space, and we only have 16 bits to work with in KVM_IRQ_LINE). However, 65k SPIs is more than would be reasonably expected on systems for years to come. In order to use vgic_is_v5(), the kvm/arm_vgic.h header is added to kvm/arm.c. Note: As the GICv5 KVM implementation currently doesn't support injecting SPIs attempts to do so will fail. This restriction will by lifted as the GICv5 KVM support evolves. Co-authored-by: Timothy Hayes Signed-off-by: Timothy Hayes Signed-off-by: Sascha Bischoff Reviewed-by: Jonathan Cameron Link: https://patch.msgid.link/20260319154937.3619520-28-sascha.bischoff@arm.com Signed-off-by: Marc Zyngier

Documentation: kvm: fix formatting of the quirks table

2026-03-11T18:16:52+00:00

A recently added quirk does not fit in the left column of the table, so it all has to be reformatted and realigned. Signed-off-by: Paolo Bonzini

KVM: x86: Introduce KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM

2026-03-11T17:41:11+00:00

Add KVM_X86_QUIRK_VMCS12_ALLOW_FREEZE_IN_SMM to allow L1 to set FREEZE_IN_SMM in vmcs12's GUEST_IA32_DEBUGCTL field, as permitted prior to commit 6b1dd26544d0 ("KVM: VMX: Preserve host's DEBUGCTLMSR_FREEZE_IN_SMM while running the guest"). Enable the quirk by default for backwards compatibility (like all quirks); userspace can disable it via KVM_CAP_DISABLE_QUIRKS2 for consistency with the constraints on WRMSR(IA32_DEBUGCTL). Note that the quirk only bypasses the consistency check. The vmcs02 bit is still owned by the host, and PMCs are not frozen during virtualized SMM. In particular, if a host administrator decides that PMCs should not be frozen during physical SMM, then L1 has no say in the matter. Fixes: 095686e6fcb4 ("KVM: nVMX: Check vmcs12->guest_ia32_debugctl on nested VM-Enter") Cc: stable@vger.kernel.org Signed-off-by: Jim Mattson Link: https://patch.msgid.link/20260205231537.1278753-1-jmattson@google.com [sean: tag for stable@, clean-up and fix goofs in the comment and docs] Signed-off-by: Sean Christopherson [Rename quirk. - Paolo] Signed-off-by: Paolo Bonzini