kernel/linux.git/Documentation/virt/kvm/api.rst, branch v7.1

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

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: 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

KVM: always define KVM_CAP_SYNC_MMU

2026-02-28T14:31:35+00:00

KVM_CAP_SYNC_MMU is provided by KVM's MMU notifiers, which are now always available. Move the definition from individual architectures to common code. Signed-off-by: Paolo Bonzini

Merge tag 'kvm-s390-next-7.0-1' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2026-02-11T17:52:27+00:00

- gmap rewrite: completely new memory management for kvm/s390 - vSIE improvement - maintainership change for s390 vfio-pci - small quality of life improvement for protected guests

Merge tag 'kvm-x86-misc-6.20' of https://github.com/kvm-x86/linux into HEAD

2026-02-09T17:53:47+00:00

KVM x86 misc changes for 6.20 - Disallow changing the virtual CPU model if L2 is active, for all the same reasons KVM disallows change the model after the first KVM_RUN. - Fix a bug where KVM would incorrectly reject host accesses to PV MSRs that were advertised as supported to userspace when running with KVM_CAP_ENFORCE_PV_FEATURE_CPUID enabled. - Fix a bug where KVM would attempt to read protect guest state (CR3) when configuring an async #PF entry. - Fail the build if EXPORT_SYMBOL_GPL or EXPORT_SYMBOL is used in KVM (for x86 only) to enforce usage of EXPORT_SYMBOL_FOR_KVM_INTERNAL. Explicitly allow the few exports that are intended for external usage. - Ignore -EBUSY when checking nested events after a vCPU exits blocking as the WARN is user-triggerable, and because exiting to userspace on -EBUSY does more harm than good in pretty much every situation. - Throw in the towel and drop the WARN on INIT/SIPI being blocked when vCPU is in Wait-For-SIPI, as playing whack-a-mole with syzkaller turned out to be an unwinnable game. - Add support for new Intel instructions that don't require anything beyond enumerating feature flags to userspace. - Grab SRCU when reading PDPTRs in KVM_GET_SREGS2. - Add WARNs to guard against modifying KVM's CPU caps outside of the intended setup flow, as nested VMX in particular is sensitive to unexpected changes in KVM's golden configuration. - Add a quirk to allow userspace to opt-in to actually suppress EOI broadcasts when the suppression feature is enabled by the guest (currently limited to split IRQCHIP, i.e. userspace I/O APIC). Sadly, simply fixing KVM to honor Suppress EOI Broadcasts isn't an option as some userspaces have come to rely on KVM's buggy behavior (KVM advertises Supress EOI Broadcast irrespective of whether or not userspace I/O APIC supports Directed EOIs). - Minor cleanups.

Merge tag 'kvm-x86-svm-6.20' of https://github.com/kvm-x86/linux into HEAD

2026-02-09T17:51:37+00:00

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.

KVM: s390: Storage key manipulation IOCTL

2026-02-04T16:00:10+00:00

Add a new IOCTL to allow userspace to manipulate storage keys directly. This will make it easier to write selftests related to storage keys. Acked-by: Heiko Carstens Signed-off-by: Claudio Imbrenda