[PATCH v3 00/62] KVM: iommu: Overhaul device posted IRQs support

Sean Christopherson
2025-06-11T22:46:56Z

Marc/Oliver,

Patch 1 is an arm64 fix that I'm guessing you'll want to grab for 6.16.
Assuming that's the case, I'll make sure this series lands on top of
kvm/master (or maybe an -rc?) at the appropriate point in time. Though if you
can grab the patch sooner than later, that'd be super helpful :-)

Oh, and the other patches are of interest to arm64 are:

[PATCH v3 32/62] KVM: Don't WARN if updating IRQ bypass route fails
[PATCH v3 33/62] KVM: Fold kvm_arch_irqfd_route_changed() into kvm_arch_update_irqfd_routing()

In theory, I _think_ those could be moved earlier so that there aren't
multi-arch patches buried in a massive x86-centric series, but I really don't
want to try and re-disentangle x86's posted interrupt mess at this point.

TL;DR: Overhaul device posted interrupts in KVM and IOMMU, and AVIC in
general.

This applies on the series to add CONFIG_KVM_IOAPIC (and to kill irq_comm.c):

https://lore.kernel.org/all/20250611213557.294358-1-seanjc@google.com

Fix a variety of bugs related to device posted IRQs, especially on the
AMD side, and clean up KVM's implementation (this series actually removes
more code than it adds).

Batch #1 is new in this version, and consists of two aforementioned arm64
changes.

Batch #2 is mostly SVM specific:

- Cleans up various warts and bugs in the IRTE tracking
- Fixes AVIC to not reject large VMs (honor KVM's ABI)
- Wire up AVIC to enable_ipiv to support disabling IPI virtualization while
still utilizing device posted interrupts, and to workaround erratum #1235.

Batch #3 overhauls the guts of IRQ bypass in KVM, and moves the vast majority
of the logic to common x86; only the code that needs to communicate with the
IOMMU is truly vendor specific.

Batch #4 is more SVM/AVIC cleanups that are made possible by batch #3.

Batch #5 adds WARNs and drops dead code after all the previous cleanups and
fixes (I don't want to add the WARNs earlier; I don't see any point in adding
WARNs in code that's known to be broken).

Batch #6 is yet more SVM/AVIC cleanups, with the specific goal of configuring
IRTEs to generate GA log interrupts if and only if KVM actually needs a wake
event.

v3:
- Rebase on kvm/next to pick up relevant arm64 irqfd routing changes, and
account for arm64 as appropriate.
- Fix a suspiciously similar bug in arm64's version of
kvm_arch_irqfd_route_changed().
- Add a patch to rename kvm_set_msi_irq() to kvm_msi_to_lapic_irq().

v2:
- https://lore.kernel.org/all/20250523010004.3240643-1-seanjc@google.com
- Drop patches that were already merged.
- Move code into irq.c, not x86.c. [Paolo]
- Collect review/testing tags. [Sairaj, Vasant]
- Sqaush fixup for a comment that was added in the prior patch. [Sairaj]
- Rewrote the changelog for "Delete IRTE link from previous vCPU irrespective
of new routing". [Sairaj]
- Actually drop "struct amd_svm_iommu_ir" and all usage in "Track per-vCPU
IRTEs using kvm_kernel_irqfd structure" (the previous version was getting
hilarious lucky with struct offsets). [Sairaj]
- Drop unused params from kvm_pi_update_irte() and pi_update_irte(). [Sairaj]
- Document the rules and behavior of amd_iommu_update_ga(). [Joerg]
- Fix a changelog typo. [Paolo]
- Document that GALogIntr isn't cached, i.e. can be safely updated without
an invalidation. [Joao, Vasant]
- Rework avic_vcpu_{load,put}() to use an enumerated parameter instead of a
series of booleans. [Paolo]
- Drop a redundant "&& new". [Francesco]
- Drop the *** DO NOT MERGE *** testing hack patches.

v1: https://lore.kernel.org/all/20250404193923.1413163-1-seanjc@google.com

Maxim Levitsky (2):
KVM: SVM: Add enable_ipiv param, never set IsRunning if disabled
KVM: SVM: Disable (x2)AVIC IPI virtualization if CPU has erratum #1235

Sean Christopherson (60):
KVM: arm64: Explicitly treat routing entry type changes as changes
KVM: arm64: WARN if unmapping vLPI fails
KVM: Pass new routing entries and irqfd when updating IRTEs
KVM: SVM: Track per-vCPU IRTEs using kvm_kernel_irqfd structure
KVM: SVM: Delete IRTE link from previous vCPU before setting new IRTE
iommu/amd: KVM: SVM: Delete now-unused cached/previous GA tag fields
KVM: SVM: Delete IRTE link from previous vCPU irrespective of new
routing
KVM: SVM: Drop pointless masking of default APIC base when setting
V_APIC_BAR
KVM: SVM: Drop pointless masking of kernel page pa's with AVIC HPA
masks
KVM: SVM: Add helper to deduplicate code for getting AVIC backing page
KVM: SVM: Drop vcpu_svm's pointless avic_backing_page field
KVM: SVM: Inhibit AVIC if ID is too big instead of rejecting vCPU
creation
KVM: SVM: Drop redundant check in AVIC code on ID during vCPU creation
KVM: SVM: Track AVIC tables as natively sized pointers, not "struct
pages"
KVM: SVM: Drop superfluous "cache" of AVIC Physical ID entry pointer
KVM: VMX: Move enable_ipiv knob to common x86
KVM: VMX: Suppress PI notifications whenever the vCPU is put
KVM: SVM: Add a comment to explain why avic_vcpu_blocking() ignores
IRQ blocking
iommu/amd: KVM: SVM: Use pi_desc_addr to derive ga_root_ptr
iommu/amd: KVM: SVM: Pass NULL @vcpu_info to indicate "not guest mode"
KVM: SVM: Stop walking list of routing table entries when updating
IRTE
KVM: VMX: Stop walking list of routing table entries when updating
IRTE
KVM: SVM: Extract SVM specific code out of get_pi_vcpu_info()
KVM: x86: Move IRQ routing/delivery APIs from x86.c => irq.c
KVM: x86: Nullify irqfd->producer after updating IRTEs
KVM: x86: Dedup AVIC vs. PI code for identifying target vCPU
KVM: x86: Move posted interrupt tracepoint to common code
KVM: SVM: Clean up return handling in avic_pi_update_irte()
iommu: KVM: Split "struct vcpu_data" into separate AMD vs. Intel
structs
KVM: Don't WARN if updating IRQ bypass route fails
KVM: Fold kvm_arch_irqfd_route_changed() into
kvm_arch_update_irqfd_routing()
KVM: x86: Track irq_bypass_vcpu in common x86 code
KVM: x86: Skip IOMMU IRTE updates if there's no old or new vCPU being
targeted
KVM: x86: Don't update IRTE entries when old and new routes were !MSI
KVM: SVM: Revert IRTE to legacy mode if IOMMU doesn't provide IR
metadata
KVM: SVM: Take and hold ir_list_lock across IRTE updates in IOMMU
iommu/amd: Document which IRTE fields amd_iommu_update_ga() can modify
iommu/amd: KVM: SVM: Infer IsRun from validity of pCPU destination
iommu/amd: Factor out helper for manipulating IRTE GA/CPU info
iommu/amd: KVM: SVM: Set pCPU info in IRTE when setting vCPU affinity
iommu/amd: KVM: SVM: Add IRTE metadata to affined vCPU's list if AVIC
is inhibited
KVM: SVM: Don't check for assigned device(s) when updating affinity
KVM: SVM: Don't check for assigned device(s) when activating AVIC
KVM: SVM: WARN if (de)activating guest mode in IOMMU fails
KVM: SVM: Process all IRTEs on affinity change even if one update
fails
KVM: SVM: WARN if updating IRTE GA fields in IOMMU fails
KVM: x86: Drop superfluous "has assigned device" check in
kvm_pi_update_irte()
KVM: x86: WARN if IRQ bypass isn't supported in kvm_pi_update_irte()
KVM: x86: WARN if IRQ bypass routing is updated without in-kernel
local APIC
KVM: SVM: WARN if ir_list is non-empty at vCPU free
KVM: x86: Decouple device assignment from IRQ bypass
KVM: VMX: WARN if VT-d Posted IRQs aren't possible when starting IRQ
bypass
KVM: SVM: Use vcpu_idx, not vcpu_id, for GA log tag/metadata
iommu/amd: WARN if KVM calls GA IRTE helpers without virtual APIC
support
KVM: SVM: Fold avic_set_pi_irte_mode() into its sole caller
KVM: SVM: Don't check vCPU's blocking status when toggling AVIC on/off
KVM: SVM: Consolidate IRTE update when toggling AVIC on/off
iommu/amd: KVM: SVM: Allow KVM to control need for GA log interrupts
KVM: SVM: Generate GA log IRQs only if the associated vCPUs is
blocking
KVM: x86: Rename kvm_set_msi_irq() => kvm_msi_to_lapic_irq()

arch/arm64/kvm/arm.c | 19 +-
arch/arm64/kvm/vgic/vgic-v4.c | 10 +-
arch/x86/include/asm/irq_remapping.h | 17 +-
arch/x86/include/asm/kvm-x86-ops.h | 2 +-
arch/x86/include/asm/kvm_host.h | 23 +-
arch/x86/include/asm/svm.h | 13 +-
arch/x86/kvm/irq.c | 152 +++++-
arch/x86/kvm/svm/avic.c | 702 ++++++++++++---------------
arch/x86/kvm/svm/svm.c | 4 +
arch/x86/kvm/svm/svm.h | 32 +-
arch/x86/kvm/trace.h | 19 +-
arch/x86/kvm/vmx/capabilities.h | 1 -
arch/x86/kvm/vmx/main.c | 2 +-
arch/x86/kvm/vmx/posted_intr.c | 140 ++----
arch/x86/kvm/vmx/posted_intr.h | 10 +-
arch/x86/kvm/vmx/vmx.c | 2 -
arch/x86/kvm/x86.c | 90 +---
drivers/iommu/amd/amd_iommu_types.h | 1 -
drivers/iommu/amd/iommu.c | 125 +++--
drivers/iommu/intel/irq_remapping.c | 10 +-
include/kvm/arm_vgic.h | 2 +-
include/linux/amd-iommu.h | 25 +-
include/linux/kvm_host.h | 9 +-
include/linux/kvm_irqfd.h | 4 +
virt/kvm/eventfd.c | 22 +-
25 files changed, 691 insertions(+), 745 deletions(-)

base-commit: 06880162469d702d052e5d51b49a24e43f182af8
--
2.50.0.rc1.591.g9c95f17f64-goog