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

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Date:	Sun, 28 Apr 2013 13:18:01 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	Chegu Vinod <chegu_vinod@...com>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: x86: Increase the "hard" max VCPU limit

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@...com>
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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