Re: [PATCH v11 11/20] x86/virt/tdx: Fill out TDMRs to cover all TDX memory regions

[Huang, Kai]

On Mon, 2023-06-12 at 17:33 +0300, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
> On Mon, Jun 12, 2023 at 02:33:58AM +0000, Huang, Kai wrote:
> > 
> > > 
> > > Maybe not even a pr_warn(), but something that's a bit ominous and has a
> > > chance of getting users to act.
> > 
> > Sorry I am not sure how to do.  Could you give some suggestion?
> 
> Maybe something like this would do?
> 
> I'm struggle with the warning message. Any suggestion is welcome.

I guess it would be helpful to print out the actual consumed TDMRs?

	pr_warn("consumed TDMRs reaching limit: %d used (out of %d)\n",
                                              tdmr_idx, tdmr_list->max_tdmrs);

> 
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 9cd4f6b58d4a..cc141025b249 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -627,6 +627,15 @@ static int fill_out_tdmrs(struct list_head *tmb_list,
>  	/* @tdmr_idx is always the index of last valid TDMR. */
>  	tdmr_list->nr_consumed_tdmrs = tdmr_idx + 1;
>  
> +	/*
> +	 * Warn early that kernel is about to run out of TDMRs.
> +	 *
> +	 * This is indication that TDMR allocation has to be reworked to be
> +	 * smarter to not run into an issue.
> +	 */
> +	if (tdmr_list->max_tdmrs - tdmr_list->nr_consumed_tdmrs < TDMR_NR_WARN)
> +		pr_warn("Low number of spare TDMRs\n");
> +
>  	return 0;
>  }
>  
> diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h
> index 323ce744b853..17efe33847ae 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.h
> +++ b/arch/x86/virt/vmx/tdx/tdx.h
> @@ -98,6 +98,9 @@ struct tdx_memblock {
>  	int nid;
>  };
>  
> +/* Warn if kernel has less than TDMR_NR_WARN TDMRs after allocation */
> +#define TDMR_NR_WARN 4
> +
>  struct tdmr_info_list {
>  	void *tdmrs;	/* Flexible array to hold 'tdmr_info's */
>  	int nr_consumed_tdmrs;	/* How many 'tdmr_info's are in use */