linux-kernel - Re: [Xen-devel] [PATCH] xen, kdump: handle pv domain in paddr_vmcoreinfo

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Date:   Fri, 31 Mar 2017 10:01:59 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Jan Beulich <JBeulich@...e.com>
Cc:     Petr Tesarik <PTesarik@...e.com>, xen-devel@...ts.xenproject.org,
        boris.ostrovsky@...cle.com, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH] xen, kdump: handle pv domain in
 paddr_vmcoreinfo_note()

On 30/03/17 17:05, Jan Beulich wrote:
>>>> On 30.03.17 at 16:18, <jgross@...e.com> wrote:
>> @@ -2903,3 +2906,13 @@ int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
>>  	return -EINVAL;
>>  }
>>  EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
>> +
>> +#ifdef CONFIG_KEXEC_CORE
>> +phys_addr_t paddr_vmcoreinfo_note(void)
>> +{
>> +	if (xen_pv_domain())
>> +		return virt_to_machine(&vmcoreinfo_note).maddr;
>> +	else
>> +		return __pa((unsigned long)(char *)&vmcoreinfo_note);
> 
> I don't think you need the double cast here.
> 
> This being placed in x86 code is correct only as long as the
> assumption is correct that no other architecture will allow for
> PV guests. And this being placed in Xen code is correct only
> as long as the assumption is true that no other hypervisors
> will allow for PV guests.

With virt_to_machine() defined in arch/x86/include/asm/xen/page.h
I think changing any of those assumptions will require major work.


Juergen