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From: Jan Beulich <jbeulich@suse.com>
To: Julien Grall <julien@xen.org>
Cc: xen-devel@lists.xenproject.org,
	"Julien Grall" <jgrall@amazon.com>,
	"Roger Pau Monné" <roger.pau@citrix.com>, "Wei Liu" <wl@xen.org>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>
Subject: Re: [PATCH 07/17] xen/x86: traps: Convert __page_fault_type() to use typesafe MFN
Date: Mon, 20 Apr 2020 11:19:57 +0200	[thread overview]
Message-ID: <97d8cf44-678b-29ed-995e-e0737f83566f@suse.com> (raw)
In-Reply-To: <cb09a267-32b6-9ea3-1289-a1e20ec99746@xen.org>

On 18.04.2020 13:43, Julien Grall wrote:
> On 18/04/2020 12:01, Julien Grall wrote:
>> On 26/03/2020 15:54, Jan Beulich wrote:
>>> On 22.03.2020 17:14, julien@xen.org wrote:
>>>> From: Julien Grall <jgrall@amazon.com>
>>>>
>>>> Note that the code is now using cr3_to_mfn() to get the MFN. This is
>>>> slightly different as the top 12-bits will now be masked.
>>>
>>> And here I agree with the change. Hence it is even more so important
>>> that the patch introducing the new helper(s) first gets sorted.
>>> Should there be further patches in this series with this same
>>> interaction issue, I won't point it out again and may not respond at
>>> all if I see no other issues.
>>
>> I will update the commit message explaining the reason of using cr3_to_mfn() and look at the other user.
> 
> Looking at the code again, there are a few users that don't mask the top 12-bits. I am trying to understand why this has never been an issue so far.
> 
> Wouldn't it break when bit 63 (no flush) is set?

Yes; I guess those uses are case where bit 63 can't / won't be set.
Just like the register, which doesn't store the bit, I think we
avoid storing the bit set as well. But correctness of the non-
masking variants can only be established by looking at every
individual site.

> If so, maybe I should split the work from typesafe.

Maybe better indeed.

Jan


  reply	other threads:[~2020-04-20  9:20 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-22 16:14 [Xen-devel] [PATCH 00/17] Bunch of typesafe conversion julien
2020-03-22 16:14 ` [Xen-devel] [PATCH 01/17] xen/x86: Introduce helpers to generate/convert the CR3 from/to a MFN/GFN julien
2020-03-25 14:46   ` Jan Beulich
2020-03-28 10:14     ` Julien Grall
2020-03-30  7:38       ` Jan Beulich
2020-04-16 11:50         ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 02/17] xen/x86_64: Convert do_page_walk() to use typesafe MFN julien
2020-03-25 14:51   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 03/17] xen/mm: Move the MM types in a separate header julien
2020-03-25 15:00   ` Jan Beulich
2020-03-25 18:09     ` Julien Grall
2020-03-26  9:02       ` Jan Beulich
2020-03-28 10:15         ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 04/17] xen: Convert virt_to_mfn() and mfn_to_virt() to use typesafe MFN julien
2020-03-25 15:27   ` Jan Beulich
2020-03-25 18:21     ` Julien Grall
2020-03-26  9:09       ` Jan Beulich
2020-03-28 10:33         ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 05/17] xen/x86: Remove the non-typesafe version of pagetable_* helpers julien
2020-03-26 15:39   ` Jan Beulich
2020-03-28 10:52     ` Julien Grall
2020-03-30  7:52       ` Jan Beulich
2020-04-18 10:23         ` Julien Grall
2020-04-20  9:16           ` Jan Beulich
2020-04-20 10:10             ` Julien Grall
2020-04-20 12:14               ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 06/17] xen/x86: mm: Fix the comment on top put_page_from_l2e() to use 'mfn' julien
2020-03-26 15:51   ` Jan Beulich
2020-04-18 10:54     ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 07/17] xen/x86: traps: Convert __page_fault_type() to use typesafe MFN julien
2020-03-26 15:54   ` Jan Beulich
2020-04-18 11:01     ` Julien Grall
2020-04-18 11:43       ` Julien Grall
2020-04-20  9:19         ` Jan Beulich [this message]
2020-03-22 16:14 ` [Xen-devel] [PATCH 08/17] xen/x86: traps: Convert show_page_walk() " julien
2020-03-22 16:14 ` [Xen-devel] [PATCH 09/17] xen/x86: Reduce the number of use of l*e_{from, get}_pfn() julien
2020-03-27 10:52   ` Jan Beulich
2020-03-28 10:53     ` Julien Grall
2020-03-22 16:14 ` [Xen-devel] [PATCH 10/17] xen/x86: pv: Use maddr_to_mfn(...) instead of the open-coding version julien
2020-03-27 11:34   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 11/17] xen/x86: nested_ept: Fix typo in the message in nept_translate_l2ga() julien
2020-03-27 11:35   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 12/17] xen/x86: p2m: Remove duplicate error message in p2m_pt_audit_p2m() julien
2020-03-27 11:35   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 13/17] xen/x86: p2m: Reflow P2M_PRINTK()s " julien
2020-03-27 11:36   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 14/17] xen/x86: mm: Re-implement set_gpfn_from_mfn() as a static inline function julien
2020-03-27 12:44   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 15/17] xen/x86: p2m: Rework printk format in audit_p2m() julien
2020-03-27 12:45   ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 16/17] xen/mm: Convert {s, g}et_gpfn_from_mfn() to use typesafe MFN julien
2020-03-23 12:11   ` Hongyan Xia
2020-03-23 12:26     ` Julien Grall
2020-03-27 13:15   ` Jan Beulich
2020-03-28 11:14     ` Julien Grall
2020-03-30  8:10       ` Jan Beulich
2020-03-22 16:14 ` [Xen-devel] [PATCH 17/17] xen: Switch parameter in get_page_from_gfn to use typesafe gfn julien
2020-03-23  8:37   ` Paul Durrant
2020-03-23 10:26     ` Julien Grall
2020-03-27 13:50   ` Jan Beulich
2020-03-27 13:59     ` Julien Grall

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