[Xen-devel] Re: [PATCH] Qemu: Add sanity check for vcpu config

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Wouldn't xend be a more sensible place to do the check? It can certainly
result in a better error message, I would have thought.

 -- Keir

On 21/03/2010 15:09, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:

> From 4d483620c863f626543fdc407c2951ceef49623e Mon Sep 17 00:00:00 2001
> From: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> Date: Sun, 21 Mar 2010 22:48:04 +0800
> Subject: [PATCH] Qemu: Add sanity check for vcpu config
> 
> Currently Xen/Qemu support max 128 vcpus. To avoid mis-setting
> at config file, this patch add sanity check for vcpu config.
> 1. maxvcpus and vcpus should no more than HVM_MAX_VCPUS (128)
> 2. vcpus should no more than maxvcpus.
> 
> Signed-off-by: Liu, Jinsong <jinsong.liu@xxxxxxxxx>
> ---
>  vl.c |   30 ++++++++++++++++++++++++++++++
>  1 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/vl.c b/vl.c
> index 30debd7..d69d90c 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -4706,6 +4706,34 @@ static void termsig_setup(void)
>  
>  #endif
>  
> +/* 32bit Hamming weight */
> +unsigned int hweight32(unsigned int w)
> +{
> + unsigned int res = w - ((w >> 1) & 0x55555555);
> + res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
> + res = (res + (res >> 4)) & 0x0F0F0F0F;
> + res = res + (res >> 8);
> + return (res + (res >> 16)) & 0x000000FF;
> +}
> +
> +static void vcpu_sanity_check(void)
> +{
> +    int i, vcpu_avail_weight = 0;
> +
> +    for (i=0; i<((HVM_MAX_VCPUS + 31)/32); i++)
> +        vcpu_avail_weight += hweight32(vcpu_avail[i]);
> +
> +    if (vcpus > HVM_MAX_VCPUS) {
> +        fprintf(stderr, "maxvcpus and vcpus should not more than %d\n",
> +                         HVM_MAX_VCPUS);
> +        exit(EXIT_FAILURE);
> +    }
> +    if (vcpu_avail_weight > vcpus) {
> +        fprintf(stderr, "vcpus should not more than maxvcpus\n");
> +        exit(EXIT_FAILURE);
> +    }
> +}
> +
>  #define STEP   8   /* 8 characters fill uint32_t bitmap */
>  #define SPACE  8   /* space for non-hex characters in vcpu str */
>  #define MAX_VCPU_STR_LEN    ((HVM_MAX_VCPUS + 3)/4 + SPACE)
> @@ -5569,6 +5597,8 @@ int main(int argc, char **argv, char **envp)
>          exit(1);
>      }
>  
> +    vcpu_sanity_check();
> +
>      if (nographic) {
>         if (serial_device_index == 0)
>             serial_devices[0] = "stdio";



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