[PATCH 54/60] kvm: x86: Restrict KVM planes support to KVM_IRQCHIP_SPLIT
From: Jörg Rödel <joro@8bytes.org>
Date: 2026-06-08 14:43:29
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, lkml, loongarch
Subsystem:
kernel virtual machine (kvm), kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Paolo Bonzini, Sean Christopherson, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Joerg Roedel <redacted> The code right now only supports plane-aware IOAPIC IRQ routing for IRQ-chip in split mode. Enforce that restriction in the KVM x86 code. Signed-off-by: Joerg Roedel <redacted> --- arch/x86/kvm/x86.c | 8 ++++++-- include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 5 +++++ 3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c6910356b061..0b9fa1059481 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -490,6 +490,10 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_x86_default_max_planes); unsigned kvm_arch_max_planes(struct kvm *kvm) { + /* For now, planes are only supported with irqchip=split */ + if (!irqchip_split(kvm)) + return 1; + return kvm_x86_call(max_planes)(kvm); }
@@ -6833,7 +6837,7 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, if (cap->args[0] > KVM_MAX_IRQ_ROUTES) goto split_irqchip_unlock; r = -EEXIST; - if (irqchip_in_kernel(kvm)) + if (irqchip_in_kernel(kvm) || kvm->has_planes) goto split_irqchip_unlock; if (kvm->created_vcpus) goto split_irqchip_unlock;
@@ -7398,7 +7402,7 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) goto create_irqchip_unlock; r = -EINVAL; - if (kvm->created_vcpus) + if (kvm->created_vcpus || kvm->has_planes) goto create_irqchip_unlock; r = kvm_pic_init(kvm);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 3b62fb354267..dbf81e2520f2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -918,6 +918,7 @@ struct kvm { struct list_head gpc_list; struct kvm_plane *planes[KVM_MAX_PLANES]; + bool has_planes; /* * created_vcpus is protected by kvm->lock, and is incremented
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8f1a16af519a..ff27cdbe8d92 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -5477,6 +5477,10 @@ static int kvm_vm_ioctl_create_plane(struct kvm *kvm, unsigned id) WARN_ON_ONCE(id >= KVM_MAX_PLANES)) return -EINVAL; + /* Planes are only supported with in-kernel IRQ-chip */ + if (!kvm_arch_irqchip_in_kernel(kvm)) + return -EINVAL; + guard(mutex)(&kvm->lock); if (kvm->planes[id]) return -EEXIST;
@@ -5498,6 +5502,7 @@ static int kvm_vm_ioctl_create_plane(struct kvm *kvm, unsigned id) goto put_kvm; } + kvm->has_planes = true; fd_install(fd, file); return fd;
--
2.53.0