From: Bhupinder Thakur <bhupinder.thakur@linaro.org>
To: Wei Liu <wei.liu2@citrix.com>
Cc: xen-devel@lists.xenproject.org,
Julien Grall <julien.grall@arm.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Ian Jackson <ian.jackson@eu.citrix.com>
Subject: Re: [PATCH 06/14 v4] xen/arm: vpl011: Add a new domctl API to initialize vpl011
Date: Mon, 19 Jun 2017 18:41:18 +0530 [thread overview]
Message-ID: <CACtJ1JSgRFONcjjAAe65TB5hX5g5PEGsbtr0ttFZJdEFfv7otw@mail.gmail.com> (raw)
In-Reply-To: <20170619114720.rmdq5nrs3a3hbynn@citrix.com>
Hi Wei,
On 19 June 2017 at 17:17, Wei Liu <wei.liu2@citrix.com> wrote:
> On Mon, Jun 19, 2017 at 12:01:32PM +0100, Julien Grall wrote:
>>
>>
>> On 19/06/17 11:59, Bhupinder Thakur wrote:
>> > Hi Julien,
>> >
>> > I was mistaken in my earlier mail about vpl011 init working if it is
>> > moved to libxl__arch_domain_create(). It is failing because as you
>> > have mentioned vuart_pfn is allocated later in xc_dom_build_image().
>> >
>> > Can we delay mapping of this page in Xen until the ring buffer is
>> > actually required by the emulation code for reading/writing data. By
>> > that time, the page would have been physically mapped.
>>
>> You would not be able to report an error if you fail to map it. But this
>> looks like to me a workaround for a tool problem.
>>
>> Anyway, as I said, I'd like feedback from the tools maintainers to see how
>> we can proceed.
>>
>
> Is there a summary of the problem, is there a particular email in this
> thread I should look at? Sorry I'm swamped by emails and patches at the
> moment.
I will summarize the problem.
It was decided to call domain_vpl011_init() from inside
libxl__arch_domain_create() to initialize vpl011. However,
domain_vpl011_init() fails to map the the vuart GFN because it has not
been physically mapped yet by the toolstack.
The following call flows highlights the issue.
libxl__domain_build() ---> libxl__build_pv ---> libxl__build_dom()
----> xc_dom_build_image() ---> alloc_magic_pages() ----> vuart GFN
allocated/mapped here
libxl__domain_build() ----> libxl__build_pre() ---->
libxl__arch_domain_create() ----> domain_vpl011_init() ---> this call
fails as the vuart GFN has not been physically mapped yet as shown in
the first call flow.
However, libxl__build_pv() is called after libxl__build_pre(). It
means that the domain_vpl011_init() is called before
alloc_magic_pages() is called and hence the initialization fails.
For that reason, I had introduced a new function
libxl__arch_domain_create_finish() which will be called from
libxl__build_post(). I moved the domain_vpl011_init() there. However,
Julien pointed out that vuart should be initialized early in
libxl__arch_domain_create() function.
So the issue is what is the right place to call domain_vpl011_init()?
I hope it clarifies the issue.
Regards,
Bhupinder
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next prev parent reply other threads:[~2017-06-19 13:11 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-06 17:25 [PATCH 00/14 v4] PL011 emulation support in Xen Bhupinder Thakur
2017-06-06 17:25 ` [PATCH 01/14 v4] xen/arm: vpl011: Move vgic register access functions to vreg.h Bhupinder Thakur
2017-06-09 12:49 ` Julien Grall
2017-06-06 17:25 ` [PATCH 02/14 v4] xen/arm: vpl011: Define generic vreg_reg* access functions in vreg.h Bhupinder Thakur
2017-06-09 12:54 ` Julien Grall
2017-06-19 9:33 ` Andre Przywara
2017-06-19 16:53 ` Bhupinder Thakur
2017-06-19 16:59 ` Andre Przywara
2017-06-06 17:25 ` [PATCH 03/14 v4] xen/arm: vpl011: Add pl011 uart emulation in Xen Bhupinder Thakur
2017-06-06 23:02 ` Stefano Stabellini
2017-06-09 13:15 ` Julien Grall
2017-06-09 18:02 ` Stefano Stabellini
2017-06-13 8:58 ` Bhupinder Thakur
2017-06-13 9:25 ` Julien Grall
2017-06-09 13:54 ` Julien Grall
2017-06-13 10:57 ` Bhupinder Thakur
2017-06-13 12:44 ` Julien Grall
2017-06-13 17:50 ` Stefano Stabellini
2017-06-14 5:47 ` Bhupinder Thakur
2017-06-14 9:33 ` Julien Grall
2017-06-19 10:14 ` Andre Przywara
2017-06-22 5:16 ` Bhupinder Thakur
2017-06-23 12:45 ` Julien Grall
2017-06-06 17:25 ` [PATCH 04/14 v4] xen/arm: vpl011: Add support for vuart in libxl Bhupinder Thakur
2017-06-06 23:07 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 05/14 v4] xen/arm: vpl011: Allocate a new GFN in the toolstack for vuart Bhupinder Thakur
2017-06-06 23:17 ` Stefano Stabellini
2017-06-07 16:43 ` Wei Liu
2017-06-06 17:25 ` [PATCH 06/14 v4] xen/arm: vpl011: Add a new domctl API to initialize vpl011 Bhupinder Thakur
2017-06-06 23:26 ` Stefano Stabellini
2017-06-09 14:06 ` Julien Grall
2017-06-09 18:32 ` Stefano Stabellini
2017-06-14 7:35 ` Bhupinder Thakur
2017-06-14 8:34 ` Bhupinder Thakur
2017-06-09 14:13 ` Julien Grall
2017-06-14 9:16 ` Bhupinder Thakur
2017-06-14 10:15 ` Julien Grall
2017-06-15 6:33 ` Bhupinder Thakur
2017-06-19 10:59 ` Bhupinder Thakur
2017-06-19 11:01 ` Julien Grall
2017-06-19 11:47 ` Wei Liu
2017-06-19 13:11 ` Bhupinder Thakur [this message]
2017-06-20 11:16 ` Julien Grall
2017-06-20 11:42 ` Wei Liu
2017-06-21 10:18 ` Bhupinder Thakur
2017-06-06 17:25 ` [PATCH 07/14 v4] xen/arm: vpl011: Add a new vuart node in the xenstore Bhupinder Thakur
2017-06-06 23:38 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 08/14 v4] xen/arm: vpl011: Modify xenconsole to define and use a new console structure Bhupinder Thakur
2017-06-07 1:13 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 09/14 v4] xen/arm: vpl011: Modify xenconsole functions to take console structure as input Bhupinder Thakur
2017-06-07 0:43 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 10/14 v4] xen/arm: vpl011: Modify xenconsole to support multiple consoles Bhupinder Thakur
2017-06-07 1:03 ` Stefano Stabellini
2017-06-07 3:51 ` Bhupinder Thakur
2017-06-07 16:46 ` Wei Liu
2017-06-07 17:54 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 11/14 v4] xen/arm: vpl011: Add support for vuart console in xenconsole Bhupinder Thakur
2017-06-07 1:08 ` Stefano Stabellini
2017-06-07 16:44 ` Wei Liu
2017-06-06 17:25 ` [PATCH 12/14 v4] xen/arm: vpl011: Add a new vuart console type to xenconsole client Bhupinder Thakur
2017-06-06 23:41 ` Stefano Stabellini
2017-06-06 17:25 ` [PATCH 13/14 v4] xen/arm: vpl011: Add a pl011 uart DT node in the guest device tree Bhupinder Thakur
2017-06-06 17:25 ` [PATCH 14/14 v4] xen/arm: vpl011: Update documentation for vuart console support Bhupinder Thakur
2017-06-09 13:58 ` [PATCH 00/14 v4] PL011 emulation support in Xen Julien Grall
-- strict thread matches above, loose matches on Subject: below --
2017-06-06 10:03 [PATCH 06/14 v4] xen/arm: vpl011: Add a new domctl API to initialize vpl011 Bhupinder Thakur
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