Increase KVM_MAX_VCPUS to 4096 when MAXSMP is enabled. Notable changes (when MAXSMP is enabled): * KMV_MAX_VCPUS will increase from 1024 to 4096. * KVM_MAX_VCPU_IDS will increase from 4096 to 16384. * KVM_HV_MAX_SPARSE_VCPU_SET_BITS will increase from 16 to 64. * CPUID[HYPERV_CPUID_IMPLEMENT_LIMITS (0x40000005)].EAX will now be 4096. * struct kvm will increase from 39408 B to 39792 B. * struct kvm_ioapic will increase from 5240 B to 19064 B. * The following (on-stack) bitmaps will increase from 128 B to 512 B: * dest_vcpu_bitmap in kvm_irq_delivery_to_apic. * vcpu_mask in kvm_hv_flush_tlb. * vcpu_bitmap in ioapic_write_indirect. * vp_bitmap in sparse_set_to_vcpu_mask. Signed-off-by: Kyle Meyer <kyle.meyer@xxxxxxx> --- Virtual machines with 4096 virtual CPUs have been created on 32 socket Cascade Lake and Sapphire Rapids systems. 4096 is the current maximum value because of the Hyper-V TLFS. See BUILD_BUG_ON in arch/x86/kvm/hyperv.c, commit 79661c3, and Vitaly's comment on https://lore.kernel.org/all/87r136shcc.fsf@xxxxxxxxxx. arch/x86/include/asm/kvm_host.h | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 3bc146dfd38d..91a01fa17fa7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -39,7 +39,11 @@ #define __KVM_HAVE_ARCH_VCPU_DEBUGFS +#ifdef CONFIG_MAXSMP +#define KVM_MAX_VCPUS 4096 +#else #define KVM_MAX_VCPUS 1024 +#endif /* * In x86, the VCPU ID corresponds to the APIC ID, and APIC IDs -- 2.35.3
