Re: [PATCH] kvm: initialize kvm_arch_ops in kvm_init()

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Yoshimi Ichiyanagi wrote:
> The latest version of kvm doesn't initialize kvm_arch_ops in kvm_init(), 
> which causes an error with the following sequence.
>
> 1. Load the supported arch's module.
> 2. Load the unsupported arch's module.　(loading error)
> 3. Unload the unsupported arch's module.
>
> You'll get the following error message after step 3.
> "BUG: unable to handle to handle kernel paging request at virtual 
> address xxxxxxxx"
>
> The problem here is that the unsupported arch's module overwrites 
> kvm_arch_ops of the supported arch's module at step 2.
>
> This patch initializes kvm_arch_ops upon loading architecture specific 
> kvm module, and prevents overwriting kvm_arch_ops when kvm_arch_ops is 
> already set correctly.
>
>   

Applied with edits; thanks.

Please provide a Signed-off-by: line in future patches.

See below:

> -------------------------------------------------------------------
> diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
> index 9f24f22..9287b2d 100644
> --- a/drivers/kvm/kvm_main.c
> +++ b/drivers/kvm/kvm_main.c
> @@ -1865,6 +1865,11 @@ int kvm_init_arch(struct kvm_arch_ops *ops, 
> struct module *module)
>  {
>  	int r;
>  
> +	if ( kvm_arch_ops ) {
> +		printk(KERN_ERR "kvm: already loaded the other module\n
> ");
> +		return -EOPNOTSUPP;
> +	}
> +
>   

Changed to -EEXIST.

>  static __init int kvm_init(void)
> @@ -1914,6 +1920,7 @@ static __init int kvm_init(void)
>  	static struct page *bad_page;
>  	int r = 0;
>  
> +	kvm_arch_ops = NULL;
>  	kvm_init_debug();
>  
>  	kvm_init_msr_list();
>
>   

This bit is unnecessary, no? I think kvm_init() will only be called
after the module is loaded, at which point kvm_arch_ops is initialized
from the .bss section.

-- 
error compiling committee.c: too many arguments to function


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