linux-kernel - Re: [Xen-devel] Re: [PATCH 2/3] xen: add CPU microcode update driver

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Date:	Mon, 15 Nov 2010 17:16:30 -0800
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	the arch/x86 maintainers <x86@...nel.org>,
	Xen-devel <xen-devel@...ts.xensource.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [Xen-devel] Re: [PATCH 2/3] xen: add CPU microcode update driver

On 11/15/2010 07:59 AM, Konrad Rzeszutek Wilk wrote:
>> +static enum ucode_state xen_request_microcode_user(int cpu,
>> +						   const void __user *buf, size_t size)
>> +{
>> +	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
>> +	struct xen_microcode *uc;
>> +	enum ucode_state ret;
>> +	size_t unread;
>> +
>> +	if (cpu != 0) {
>> +		/* No real firmware for non-zero cpus; just store a
>> +		   placeholder */
>> +		size = 0;
>> +	}
>> +
>> +	if (uci->mc != NULL) {
>> +		vfree(uci->mc);
>> +		uci->mc = NULL;
>> +	}
>> +
>> +	ret = UCODE_ERROR;
>> +	uc = vmalloc(sizeof(*uc) + size);
>> +	if (uc == NULL)
>> +		goto out;
>> +
>> +	uc->len = size;
>> +
>> +	ret = UCODE_NFOUND;
>> +
>> +	/* XXX This sporadically returns uncopied bytes, so we return
>> +	   EFAULT.  As far as I can see, the usermode code
>            ^^^^^ UCODE_NFOUND.
>> +	   (microcode_ctl) isn't doing anything wrong... */
> Is this still valid? Looking at AMD it checks for a magic key and the Intel
> just copies without checks.

Probably not.

    J
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