From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Bertrand Marquis <Bertrand.Marquis@arm.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
Stefano Stabellini <sstabellini@kernel.org>,
Julien Grall <julien@xen.org>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [PATCH 0/7] xen/arm: Emulate ID registers
Date: Mon, 30 Nov 2020 10:36:00 +0000 [thread overview]
Message-ID: <e119d6ff-dc61-0fd7-6da5-3e4e1b51839c@citrix.com> (raw)
In-Reply-To: <1BAAADF6-9E29-4BE5-857D-A8B51EB80712@arm.com>
On 30/11/2020 10:20, Bertrand Marquis wrote:
> Hi Andrew,
>
>> On 27 Nov 2020, at 20:07, Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>>
>> On 26/11/2020 15:51, Bertrand Marquis wrote:
>>> The goal of this serie is to emulate coprocessor ID registers so that
>>> Xen only publish to guest features that are supported by Xen and can
>>> actually be used by guests.
>>> One practical example where this is required are SVE support which is
>>> forbidden by Xen as it is not supported, but if Linux is compiled with
>>> it, it will crash on boot. An other one is AMU which is also forbidden
>>> by Xen but one Linux compiled with it would crash if the platform
>>> supports it.
>>>
>>> To be able to emulate the coprocessor registers defining what features
>>> are supported by the hardware, the TID3 bit of HCR must be disabled and
>>> Xen must emulated the values of those registers when an exception is
>>> catched when a guest is accessing it.
>>>
>>> This serie is first creating a guest cpuinfo structure which will
>>> contain the values that we want to publish to the guests and then
>>> provides the proper emulationg for those registers when Xen is getting
>>> an exception due to an access to any of those registers.
>>>
>>> This is a first simple implementation to solve the problem and the way
>>> to define the values that we provide to guests and which features are
>>> disabled will be in a future patchset enhance so that we could decide
>>> per guest what can be used or not and depending on this deduce the bits
>>> to activate in HCR and the values that we must publish on ID registers.
>>>
>>> Bertrand Marquis (7):
>>> xen/arm: Add ID registers and complete cpufinfo
>>> xen/arm: Add arm64 ID registers definitions
>>> xen/arm: create a cpuinfo structure for guest
>>> xen/arm: Add handler for ID registers on arm64
>>> xen/arm: Add handler for cp15 ID registers
>>> xen/arm: Add CP10 exception support to handle VMFR
>>> xen/arm: Activate TID3 in HCR_EL2
>> CI found an ARM randconfig failure against this series.
>>
>> https://gitlab.com/xen-project/patchew/xen/-/pipelines/221798884
>>
>> I have admit that I can't spot an obvious connection so it might be
>> collateral damage from elsewhere, but does need looking at irrespective.
> This absolutely right, there is a bug in my code and i will send a V2 to fix it.
>
> Very nice finding, i am wondering why my tests did not point this out.
Its randconfig, so every time the test runs, it picks a new random
Kconfig configuration.
Sadly, it is non-deterministic, and not necessarily the fault of change
the test ran against. We're probably going to have to tweak how we run
these tests before the CI goes too much further.
~Andrew
next prev parent reply other threads:[~2020-11-30 10:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-26 15:51 [PATCH 0/7] xen/arm: Emulate ID registers Bertrand Marquis
2020-11-26 15:51 ` [PATCH 1/7] xen/arm: Add ID registers and complete cpufinfo Bertrand Marquis
2020-11-26 15:51 ` [PATCH 2/7] xen/arm: Add arm64 ID registers definitions Bertrand Marquis
2020-11-26 15:51 ` [PATCH 3/7] xen/arm: create a cpuinfo structure for guest Bertrand Marquis
2020-11-26 15:51 ` [PATCH 4/7] xen/arm: Add handler for ID registers on arm64 Bertrand Marquis
2020-11-26 15:51 ` [PATCH 5/7] xen/arm: Add handler for cp15 ID registers Bertrand Marquis
2020-11-26 15:51 ` [PATCH 6/7] xen/arm: Add CP10 exception support to handle VMFR Bertrand Marquis
2020-11-26 15:51 ` [PATCH 7/7] xen/arm: Activate TID3 in HCR_EL2 Bertrand Marquis
2020-11-27 20:07 ` [PATCH 0/7] xen/arm: Emulate ID registers Andrew Cooper
2020-11-30 10:20 ` Bertrand Marquis
2020-11-30 10:36 ` Andrew Cooper [this message]
2020-11-30 10:46 ` Bertrand Marquis
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