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From: Peter Hurley <peter@hurleysoftware.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Gleb Natapov <gleb@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 0/5] [v3] fix illegal use of __pa() in KVM code
Date: Tue, 26 Feb 2013 07:45:27 -0500	[thread overview]
Message-ID: <1361882727.3235.14.camel@thor.lan> (raw)
In-Reply-To: <512B784E.5070002@linux.vnet.ibm.com>

On Mon, 2013-02-25 at 06:42 -0800, Dave Hansen wrote:
> On 02/24/2013 01:28 PM, Peter Hurley wrote:
> > Now that the alloc_remap() has been/is being removed, is most/all of
> > this being reverted?
> 
> I _believe_ alloc_remap() is the only case where we actually remapped
> low memory.  However, there is still other code that does __pa()
> translations for percpu areas: per_cpu_ptr_to_phys().  I _think_ it's
> still theoretically possible to get some percpu data in the vmalloc() area.
> 
> > So in short, my questions are:
> > 1) is the slow_virt_to_phys() necessary anymore?

Ah, yep. Thanks for pointing out per_cpu_ptr_to_phys().

> kvm_vcpu_arch has a
> 
>         struct pvclock_vcpu_time_info hv_clock;
> 
> and I believe I mistook the two 'hv_clock's for each other.  However,
> this doesn't hurt anything, and the performance difference is probably
> horribly tiny.

Ok. It was confusing because the fixmap of that same phys memblock done
by pvclock was broken and I couldn't understand why the hvclock memblock
needed to be looked-up per cpu. Mystery solved.

Regards,
Peter Hurley



WARNING: multiple messages have this Message-ID (diff)
From: Peter Hurley <peter@hurleysoftware.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Gleb Natapov <gleb@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 0/5] [v3] fix illegal use of __pa() in KVM code
Date: Tue, 26 Feb 2013 07:45:27 -0500	[thread overview]
Message-ID: <1361882727.3235.14.camel@thor.lan> (raw)
In-Reply-To: <512B784E.5070002@linux.vnet.ibm.com>

On Mon, 2013-02-25 at 06:42 -0800, Dave Hansen wrote:
> On 02/24/2013 01:28 PM, Peter Hurley wrote:
> > Now that the alloc_remap() has been/is being removed, is most/all of
> > this being reverted?
> 
> I _believe_ alloc_remap() is the only case where we actually remapped
> low memory.  However, there is still other code that does __pa()
> translations for percpu areas: per_cpu_ptr_to_phys().  I _think_ it's
> still theoretically possible to get some percpu data in the vmalloc() area.
> 
> > So in short, my questions are:
> > 1) is the slow_virt_to_phys() necessary anymore?

Ah, yep. Thanks for pointing out per_cpu_ptr_to_phys().

> kvm_vcpu_arch has a
> 
>         struct pvclock_vcpu_time_info hv_clock;
> 
> and I believe I mistook the two 'hv_clock's for each other.  However,
> this doesn't hurt anything, and the performance difference is probably
> horribly tiny.

Ok. It was confusing because the fixmap of that same phys memblock done
by pvclock was broken and I couldn't understand why the hvclock memblock
needed to be looked-up per cpu. Mystery solved.

Regards,
Peter Hurley


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  reply	other threads:[~2013-02-26 12:45 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-01-22 21:24 [PATCH 0/5] [v3] fix illegal use of __pa() in KVM code Dave Hansen
2013-01-22 21:24 ` Dave Hansen
2013-01-22 21:24 ` [PATCH 1/5] make DEBUG_VIRTUAL work earlier in boot Dave Hansen
2013-01-22 21:24   ` Dave Hansen
2013-01-26  1:51   ` [tip:x86/mm] x86, mm: Make " tip-bot for Dave Hansen
2013-01-22 21:24 ` [PATCH 2/5] pagetable level size/shift/mask helpers Dave Hansen
2013-01-22 21:24   ` Dave Hansen
2013-01-26  1:52   ` [tip:x86/mm] x86, mm: Pagetable " tip-bot for Dave Hansen
2013-01-22 21:24 ` [PATCH 3/5] use new pagetable helpers in try_preserve_large_page() Dave Hansen
2013-01-22 21:24   ` Dave Hansen
2013-01-26  1:53   ` [tip:x86/mm] x86, mm: Use " tip-bot for Dave Hansen
2013-01-22 21:24 ` [PATCH 4/5] create slow_virt_to_phys() Dave Hansen
2013-01-22 21:24   ` Dave Hansen
2013-01-26  1:54   ` [tip:x86/mm] x86, mm: Create slow_virt_to_phys() tip-bot for Dave Hansen
2013-01-22 21:24 ` [PATCH 5/5] fix kvm's use of __pa() on percpu areas Dave Hansen
2013-01-22 21:24   ` Dave Hansen
2013-01-23  0:08   ` Marcelo Tosatti
2013-01-23  0:08     ` Marcelo Tosatti
2013-01-26  1:56   ` [tip:x86/mm] x86, kvm: Fix " tip-bot for Dave Hansen
2013-01-25 23:15 ` [PATCH 0/5] [v3] fix illegal use of __pa() in KVM code Dave Hansen
2013-01-25 23:15   ` Dave Hansen
2013-02-24 21:28 ` Peter Hurley
2013-02-24 21:28   ` Peter Hurley
2013-02-25  8:30   ` Gleb Natapov
2013-02-25  8:30     ` Gleb Natapov
2013-02-25 14:42   ` Dave Hansen
2013-02-25 14:42     ` Dave Hansen
2013-02-26 12:45     ` Peter Hurley [this message]
2013-02-26 12:45       ` Peter Hurley

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