linux-kernel - Re: [PATCH] drivers/xen/hypervisor: Expose VM SIF flags to userspace

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Message-ID: <c8c13453-c453-7de1-ae07-045064a938b8@oracle.com>
Date:   Tue, 29 Nov 2022 11:29:56 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Per Bilse <per.bilse@...rix.com>, linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Jan Beulich <jbeulich@...e.com>,
        "moderated list:XEN HYPERVISOR INTERFACE" 
        <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH] drivers/xen/hypervisor: Expose VM SIF flags to userspace


On 11/29/22 10:00 AM, Per Bilse wrote:
>   
> +static ssize_t flags_show(struct hyp_sysfs_attr *attr, char *buffer)
> +{
> +	static char const *const sifstr[SIFN_NUM_SIFN] = {
> +		[SIFN_PRIV]  = "privileged",
> +		[SIFN_INIT]  = "initdomain",
> +		[SIFN_MULTI] = "multiboot",
> +		[SIFN_PFN]   = "mod_start_pfn",
> +		[SIFN_VIRT]  = "virtmap"
> +	};
> +	unsigned sifnum, sifmask;
> +	ssize_t ret = 0;
> +
> +	sifmask = ~(~0U << SIFN_NUM_SIFN);  // ...0000111...
> +	if (xen_domain() && (xen_start_flags & sifmask) != 0) {
> +		for (sifnum = 0; sifnum != SIFN_NUM_SIFN; sifnum++) {
> +			if ((xen_start_flags & (1<<sifnum)) != 0)
> +				ret += sprintf(buffer+ret, "%s ", sifstr[sifnum]);
> +		}
> +		buffer[ret-1] = '\n';
> +	}
> +	return ret;
> +}


Why not simply show unprocessed xen_start_flags as a hex value?


-boris