[PATCH 28/60] kvm: Implement KVM_CAP_PLANES
From: Jörg Rödel <joro@8bytes.org>
Date: 2026-06-08 14:43:20
Also in:
kvm, kvm-riscv, kvmarm, linux-mips, lkml, loongarch
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine (kvm), kernel virtual machine for arm64 (kvm/arm64), kernel virtual machine for loongarch (kvm/loongarch), kernel virtual machine for mips (kvm/mips), kernel virtual machine for powerpc (kvm/powerpc), kernel virtual machine for risc-v (kvm/riscv), kernel virtual machine for x86 (kvm/x86), kernel virtual machine for s390 (kvm/s390), linux for powerpc (32-bit and 64-bit), loongarch, mips, risc-v architecture, s390 architecture, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Catalin Marinas, Will Deacon, Paolo Bonzini, Marc Zyngier, Oliver Upton, Tianrui Zhao, Bibo Mao, Huacai Chen, Madhavan Srinivasan, Anup Patel, Sean Christopherson, Christian Borntraeger, Janosch Frank, Claudio Imbrenda, Michael Ellerman, Thomas Bogendoerfer, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Paolo Bonzini <pbonzini@redhat.com> Introduce an architecture call-back to request the VM-specific maximum number of supported planes. Use that to implement the KVM_CAP_PLANES capability check. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Co-developed-by: Joerg Roedel <redacted> Signed-off-by: Joerg Roedel <redacted> --- arch/arm64/kvm/arm.c | 5 +++++ arch/loongarch/kvm/vm.c | 5 +++++ arch/mips/kvm/mips.c | 5 +++++ arch/powerpc/kvm/powerpc.c | 5 +++++ arch/riscv/kvm/main.c | 5 +++++ arch/s390/kvm/kvm-s390.c | 5 +++++ arch/x86/kvm/x86.c | 5 +++++ include/linux/kvm_host.h | 2 ++ virt/kvm/kvm_main.c | 4 ++++ 9 files changed, 41 insertions(+)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1e2f42134b74..7e6d2773fd39 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c@@ -200,6 +200,11 @@ static int kvm_arm_default_max_vcpus(void) return vgic_present ? kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; } +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + /** * kvm_arch_init_vm - initializes a VM data structure * @kvm: pointer to the KVM struct
diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
index 1317c718f896..14f1232c6e0c 100644
--- a/arch/loongarch/kvm/vm.c
+++ b/arch/loongarch/kvm/vm.c@@ -109,6 +109,11 @@ void kvm_arch_destroy_vm(struct kvm *kvm) kvm->arch.phyid_map = NULL; } +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) { int r;
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 776aba0af096..60870452119d 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c@@ -115,6 +115,11 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) return !!(vcpu->arch.pending_exceptions); } +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu) { return false;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 5d94e0f676ec..cfa40be20e00 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c@@ -499,6 +499,11 @@ void kvm_arch_destroy_vm(struct kvm *kvm) module_put(kvm->arch.kvm_ops->owner); } +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) { int r;
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index cb8a65273c1f..5adba3a455a3 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c@@ -17,6 +17,11 @@ DEFINE_STATIC_KEY_FALSE(kvm_riscv_vsstage_tlb_no_gpa); +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + static void kvm_riscv_setup_vendor_features(void) { /* Andes AX66: split two-stage TLBs */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e6fe83da172f..24f24ea95f86 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c@@ -3186,6 +3186,11 @@ static void sca_dispose(struct kvm *kvm) kvm->arch.sca = NULL; } +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + void kvm_arch_free_vm(struct kvm *kvm) { if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 50601ac2828f..25299c8c28e3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c@@ -482,6 +482,11 @@ static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all_except_vmx) + (KVM_LAST_EMULATED_VMX_MSR - KVM_FIRST_EMULATED_VMX_MSR + 1)]; static unsigned int num_msr_based_features; +unsigned kvm_arch_max_planes(struct kvm *kvm) +{ + return 1; +} + /* * All feature MSRs except uCode revID, which tracks the currently loaded uCode * patch, are immutable once the vCPU model is defined.
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 291bccce9b74..3ecd472c7cfa 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h@@ -1156,6 +1156,8 @@ void kvm_unlock_all_vcpus(struct kvm *kvm); void vcpu_load(struct kvm_vcpu *vcpu); void vcpu_put(struct kvm_vcpu *vcpu); +unsigned kvm_arch_max_planes(struct kvm *kvm); + #ifdef CONFIG_KVM_IOAPIC void kvm_arch_post_irq_ack_notifier_list_update(struct kvm *kvm); #else
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7a0b632e3ac0..5a0277e2ac7c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -5079,6 +5079,10 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg) case KVM_CAP_GUEST_MEMFD_FLAGS: return kvm_gmem_get_supported_flags(kvm); #endif + case KVM_CAP_PLANES: + if (kvm) + return kvm_arch_max_planes(kvm); + return 1; default: break; }
--
2.53.0