* Clarification for patch 7
@ 2014-12-17 3:40 Mario Smarduch
2015-01-07 12:39 ` Christoffer Dall
0 siblings, 1 reply; 2+ messages in thread
From: Mario Smarduch @ 2014-12-17 3:40 UTC (permalink / raw)
To: christoffer.dall@linaro.org, Marc Zyngier
Cc: Paolo Bonzini, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Hi Christoffer, Marc -
in stage2_dissolve_pmd() CONFIG_SMP is
unnecessary. At the time huge page is write protected,
until it faults and is cleared any page in the range
may be dirty not just the gpa access that caused the
fault.
The comment on another CPU is wrong, I
confused myself while testing it should not be possible for
another CPU to write to same PMD range while
another is handling its PMD fault. I ran a test with
only initrd which exposed an issue using my
test scenario, QEMU appears fine.
It also depends on user space if you first turn
on logging, do pre-copy then marking just the page
is enough. It's hard to interpret the API in this
case. It just says dirty pages since the last
call.
That patch could be resent without upsetting
the rest.
- Mario
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Clarification for patch 7
2014-12-17 3:40 Clarification for patch 7 Mario Smarduch
@ 2015-01-07 12:39 ` Christoffer Dall
0 siblings, 0 replies; 2+ messages in thread
From: Christoffer Dall @ 2015-01-07 12:39 UTC (permalink / raw)
To: Mario Smarduch
Cc: Marc Zyngier, Paolo Bonzini, kvmarm@lists.cs.columbia.edu,
kvm@vger.kernel.org
On Tue, Dec 16, 2014 at 07:40:09PM -0800, Mario Smarduch wrote:
> Hi Christoffer, Marc -
> in stage2_dissolve_pmd() CONFIG_SMP is
> unnecessary. At the time huge page is write protected,
> until it faults and is cleared any page in the range
> may be dirty not just the gpa access that caused the
> fault.
>
> The comment on another CPU is wrong, I
> confused myself while testing it should not be possible for
> another CPU to write to same PMD range while
> another is handling its PMD fault. I ran a test with
> only initrd which exposed an issue using my
> test scenario, QEMU appears fine.
>
> It also depends on user space if you first turn
> on logging, do pre-copy then marking just the page
> is enough. It's hard to interpret the API in this
> case. It just says dirty pages since the last
> call.
>
> That patch could be resent without upsetting
> the rest.
>
I think I raised all these issues on your patch, let's discuss it there.
-Christoffer
^ permalink raw reply [flat|nested] 2+ messages in thread
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