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kvm: x86: Increase MAX_VCPUS to 1024

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Increase KVM_MAX_VCPUS to 1024, so we can test larger VMs.

I'm not changing KVM_SOFT_MAX_VCPUS yet because I'm afraid it
might involve complicated questions around the meaning of
"supported" and "recommended" in the upstream tree.
KVM_SOFT_MAX_VCPUS will be changed in a separate patch.

For reference, visible effects of this change are:
- KVM_CAP_MAX_VCPUS will now return 1024 (of course)
- Default value for CPUID[HYPERV_CPUID_IMPLEMENT_LIMITS (00x40000005)].EAX
  will now be 1024
- KVM_MAX_VCPU_ID will change from 1151 to 4096
- Size of struct kvm will increase from 19328 to 22272 bytes
  (in x86_64)
- Size of struct kvm_ioapic will increase from 1780 to 5084 bytes
  (in x86_64)
- Bitmap stack variables that will grow:
  - At kvm_hv_flush_tlb() kvm_hv_send_ipi(),
    vp_bitmap[] and vcpu_bitmap[] will now be 128 bytes long
  - vcpu_bitmap at bioapic_write_indirect() will be 128 bytes long
    once patch "KVM: x86: Fix stack-out-of-bounds memory access
    from ioapic_write_indirect()" is applied

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20210903211600.2002377-3-ehabkost@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Eduardo Habkost 2021-09-03 17:15:59 -04:00 committed by Paolo Bonzini
parent 4ddacd525a
commit 074c82c8f7
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/kvm_host.h
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@ -37,7 +37,7 @@
#define __KVM_HAVE_ARCH_VCPU_DEBUGFS
#define KVM_MAX_VCPUS 288
#define KVM_MAX_VCPUS 1024
#define KVM_SOFT_MAX_VCPUS 240
/*