Re: [PATCH] KVM: x86: Increase the "hard" max VCPU limit

From: Gleb Natapov
Date: Sun Apr 28 2013 - 06:18:13 EST


On Sat, Apr 27, 2013 at 06:31:04PM -0700, Chegu Vinod wrote:
> KVM guests today use 8bit APIC ids allowing for 256 ID's. Reserving one
> ID for Broadcast interrupts should leave 255 ID's. In case of KVM there
> is no need for reserving another ID for IO-APIC so the hard max limit for
> VCPUS can be increased from 254 to 255. (This was confirmed by Gleb Natapov
> http://article.gmane.org/gmane.comp.emulators.kvm.devel/99713 )
>
> Signed-off-by: Chegu Vinod <chegu_vinod@xxxxxx>
Applied, thanks.

> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 4979778..bc57bfa 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -31,7 +31,7 @@
> #include <asm/msr-index.h>
> #include <asm/asm.h>
>
> -#define KVM_MAX_VCPUS 254
> +#define KVM_MAX_VCPUS 255
> #define KVM_SOFT_MAX_VCPUS 160
> #define KVM_USER_MEM_SLOTS 125
> /* memory slots that are not exposed to userspace */
> --
> 1.7.1

--
Gleb.
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