linux-kernel - Re: [PATCH 1/6] xen/x86/pvh: Save %rbx in xen_pvh_early_cpu

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Date:	Tue, 07 Jul 2015 16:51:42 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	david.vrabel@...rix.com, roger.pau@...rix.com,
	elena.ufimtseva@...cle.com, stefano.stabellini@...citrix.com,
	tim@....org, jbeulich@...e.com, andrew.cooper3@...rix.com,
	ian.campbell@...rix.com, wei.liu2@...rix.com,
	ian.jackson@...citrix.com, xen-devel@...ts.xenproject.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/6] xen/x86/pvh: Save %rbx in xen_pvh_early_cpu_init()

On 07/07/2015 04:26 PM, Konrad Rzeszutek Wilk wrote:
>>> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
>>> index 8afdfcc..b1508a8 100644
>>> --- a/arch/x86/xen/xen-head.S
>>> +++ b/arch/x86/xen/xen-head.S
>>> @@ -56,28 +56,28 @@ ENTRY(startup_xen)
>>>    * @entry: true if this is a secondary vcpu coming up on this entry
>>>    *         point, false if this is the boot CPU being initialized for
>>>    *         the first time (%rsi)
>>> - *
>>> - * Note: This is called as a function on the boot CPU, and is the entry point
>>> - *       on the secondary CPU.
>>>    */
>>>   ENTRY(xen_pvh_early_cpu_init)
>>> -	mov     %rsi, %r11
>>> +	mov	%rbx, -8(%rsp)
>>>   
>>> +/* Entry point for secondary CPUs */
> Actually, could you do this (since the BSP can access the stack and
> it can do jumps) - not compile tested:

Yes, this looks better, I'll try it. Thanks.

-boris


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