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| author | Kyle Meyer <kyle.meyer@hpe.com> | 2023-08-24 23:52:46 +0200 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2023-09-28 18:25:19 +0200 |
| commit | f10a570b093e60c6bd3f210ae909f014f421352a (patch) | |
| tree | b46ee5fea3ecfa8542d2ff89549f83ba036ea785 /arch/x86/kvm/Kconfig | |
| parent | KVM: x86: Force TLB flush on userspace changes to special registers (diff) | |
| download | linux-f10a570b093e60c6bd3f210ae909f014f421352a.tar.xz linux-f10a570b093e60c6bd3f210ae909f014f421352a.zip | |
KVM: x86: Add CONFIG_KVM_MAX_NR_VCPUS to allow up to 4096 vCPUs
Add a Kconfig entry to set the maximum number of vCPUs per KVM guest and
set the default value to 4096 when MAXSMP is enabled, as there are use
cases that want to create more than the currently allowed 1024 vCPUs and
are more than happy to eat the memory overhead.
The Hyper-V TLFS doesn't allow more than 64 sparse banks, i.e. allows a
maximum of 4096 virtual CPUs. Cap KVM's maximum number of virtual CPUs
to 4096 to avoid exceeding Hyper-V's limit as KVM support for Hyper-V is
unconditional, and alternatives like dynamically disabling Hyper-V
enlightenments that rely on sparse banks would require non-trivial code
changes.
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com>
Link: https://lore.kernel.org/r/20230824215244.3897419-1-kyle.meyer@hpe.com
[sean: massage changelog with --verbose, document #ifdef mess]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/Kconfig')
| -rw-r--r-- | arch/x86/kvm/Kconfig | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig index ed90f148140d..950c12868d30 100644 --- a/arch/x86/kvm/Kconfig +++ b/arch/x86/kvm/Kconfig @@ -154,4 +154,15 @@ config KVM_PROVE_MMU config KVM_EXTERNAL_WRITE_TRACKING bool +config KVM_MAX_NR_VCPUS + int "Maximum number of vCPUs per KVM guest" + depends on KVM + range 1024 4096 + default 4096 if MAXSMP + default 1024 + help + Set the maximum number of vCPUs per KVM guest. Larger values will increase + the memory footprint of each KVM guest, regardless of how many vCPUs are + created for a given VM. + endif # VIRTUALIZATION |