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From: Stefano Stabellini <sstabellini@kernel.org>
To: Juergen Gross <jgross@suse.com>
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
	 Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	 Stefano Stabellini <sstabellini@kernel.org>,
	 Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 1/3] xen: check required Xen features
Date: Thu, 22 Apr 2021 08:26:12 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.2104220823160.5018@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <20210422151007.2205-2-jgross@suse.com>

On Thu, 22 Apr 2021, Juergen Gross wrote:
> Linux kernel is not supported to run on Xen versions older than 4.0.
> 
> Add tests for required Xen features always being present in Xen 4.0
> and newer.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  drivers/xen/features.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/xen/features.c b/drivers/xen/features.c
> index 25c053b09605..60503299c9bc 100644
> --- a/drivers/xen/features.c
> +++ b/drivers/xen/features.c
> @@ -9,13 +9,26 @@
>  #include <linux/types.h>
>  #include <linux/cache.h>
>  #include <linux/export.h>
> +#include <linux/printk.h>
>  
>  #include <asm/xen/hypercall.h>
>  
> +#include <xen/xen.h>
>  #include <xen/interface/xen.h>
>  #include <xen/interface/version.h>
>  #include <xen/features.h>
>  
> +/*
> + * Linux kernel expects at least Xen 4.0.
> + *
> + * Assume some features to be available for that reason (depending on guest
> + * mode, of course).
> + */
> +#define chk_feature(f) {						\
> +		if (!xen_feature(f))					\
> +			pr_err("Xen: feature %s not available!\n", #f);	\
> +	}

I think this could be done as a static inline function in
include/xen/features.h. That way it would be available everywhere. Also,
static inlines are better than macro when it is possible to use them in
terms of code safety.


>  u8 xen_features[XENFEAT_NR_SUBMAPS * 32] __read_mostly;
>  EXPORT_SYMBOL_GPL(xen_features);
>  
> @@ -31,4 +44,9 @@ void xen_setup_features(void)
>  		for (j = 0; j < 32; j++)
>  			xen_features[i * 32 + j] = !!(fi.submap & 1<<j);
>  	}
> +
> +	if (xen_pv_domain()) {
> +		chk_feature(XENFEAT_mmu_pt_update_preserve_ad);
> +		chk_feature(XENFEAT_gnttab_map_avail_bits);
> +	}
>  }
> -- 
> 2.26.2
> 


  reply	other threads:[~2021-04-22 15:26 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-22 15:10 [PATCH 0/3] xen: remove some checks for always present " Juergen Gross
2021-04-22 15:10 ` [PATCH 1/3] xen: check required " Juergen Gross
2021-04-22 15:26   ` Stefano Stabellini [this message]
2021-04-22 15:32     ` Juergen Gross
2021-05-10 12:11   ` Boris Ostrovsky
2021-05-10 13:21     ` Juergen Gross
2021-04-22 15:10 ` [PATCH 2/3] xen: assume XENFEAT_mmu_pt_update_preserve_ad being set for pv guests Juergen Gross
2021-04-22 15:10 ` [PATCH 3/3] xen: assume XENFEAT_gnttab_map_avail_bits " Juergen Gross
2021-04-22 15:16 ` [PATCH 0/3] xen: remove some checks for always present Xen features Jan Beulich
2021-04-22 15:17   ` Juergen Gross
2021-04-22 15:23     ` Jan Beulich
2021-04-22 15:28       ` Juergen Gross
2021-04-22 15:42         ` Jan Beulich
2021-04-22 15:49           ` Juergen Gross
2021-04-22 15:51           ` Andrew Cooper
2021-05-10  7:34 ` Juergen Gross
2021-05-10 11:31   ` Peter Zijlstra

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