From: Keir Fraser <keir.xen@gmail.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: [PATCH 2/2] x86/microcode: enable boot time (pre-Dom0) loading
Date: Thu, 01 Dec 2011 05:25:40 +0000 [thread overview]
Message-ID: <CAFCC054.262CD%keir.xen@gmail.com> (raw)
In-Reply-To: <4ED7423602000078000648FE@nat28.tlf.novell.com>
On 01/12/2011 08:00, "Jan Beulich" <JBeulich@suse.com> wrote:
>>>> On 30.11.11 at 10:05, Keir Fraser <keir.xen@gmail.com> wrote:
>> On 30/11/2011 16:27, "Jan Beulich" <JBeulich@suse.com> wrote:
>>
>>>
>>> In order to not convert the spin_lock() in microcode_update_cpu() (and
>>> then obviously also all other uses on microcode_mutex) to
>>> spin_lock_irqsave() (which would be undesirable for the hypercall
>>> context in which the function also runs), the boot time handling gets
>>> done using a tasklet (instead of using on_selected_cpus()).
>>
>> Can you explain this some more? Why would the conversion to
>> spin_lock_irqsave be required when spin_lock is sufficient for current usage
>> from dom0 hypercall?
>
> Because check_lock() wants locks to be acquired consistently?
Oh I see, and we use continue_hypercall_on_cpu() in the hypercall case.
Makes sense then.
-- Keir
> Jan
>
next prev parent reply other threads:[~2011-12-01 5:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-30 16:27 [PATCH 2/2] x86/microcode: enable boot time (pre-Dom0) loading Jan Beulich
2011-11-30 9:05 ` Keir Fraser
2011-12-01 8:00 ` Jan Beulich
2011-12-01 5:25 ` Keir Fraser [this message]
2011-11-30 22:23 ` Konrad Rzeszutek Wilk
2011-12-01 8:04 ` Jan Beulich
2011-12-01 9:55 ` Ian Campbell
2011-12-01 10:02 ` Jan Beulich
2011-12-01 10:38 ` Borislav Petkov
2011-12-13 16:42 ` Konrad Rzeszutek Wilk
2011-12-01 9:48 ` Tim Deegan
2011-12-01 9:54 ` Jan Beulich
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