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From: Andrii Anisov <andrii.anisov@gmail.com>
To: Julien Grall <Julien.Grall@arm.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Oleksandr_Tyshchenko@epam.com" <Oleksandr_Tyshchenko@epam.com>,
	nd <nd@arm.com>,
	"Andrii_Anisov@epam.com" <Andrii_Anisov@epam.com>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>
Subject: Re: [PATCH 2/7] xen/arm: Remove flush_xen_text_tlb_local()
Date: Fri, 26 Apr 2019 16:50:16 +0300	[thread overview]
Message-ID: <4e365b84-122d-e613-ceaa-e2df8c865262@gmail.com> (raw)
In-Reply-To: <fb22f2a1-f3a6-a962-a9ba-54c22e5c7d2a@arm.com>



On 25.04.19 23:37, Julien Grall wrote:
> The understanding is correct. I am not entirely sure how I can improve
> the comment.
I've re-read the comment again, and realized it actually fits. So let it be.

> 
> To be honest, I am not entirely sure whether the isb() is necessary
> here. At worst, an entry of an existing mappings is not cached with the
> SCTLR_EL2.WXN set. This may only defer the problem is an entry is
> incorrectly configured before the flush. This is done early at boot (and
> will be done much earlier in [1]).Well, following this logic we may finish with TLB flush is not needed here at all. Because entries, already reached TLB, were configured before, and are believed valid. All the next will have WXN set.
But in this case, ISB is needed as an exact point from which all new TLB entries will have WXN.

> So I am kind of tempted to drop the
> isb() here.

-- 
Sincerely,
Andrii Anisov.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

WARNING: multiple messages have this Message-ID (diff)
From: Andrii Anisov <andrii.anisov@gmail.com>
To: Julien Grall <Julien.Grall@arm.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Oleksandr_Tyshchenko@epam.com" <Oleksandr_Tyshchenko@epam.com>,
	nd <nd@arm.com>,
	"Andrii_Anisov@epam.com" <Andrii_Anisov@epam.com>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>
Subject: Re: [Xen-devel] [PATCH 2/7] xen/arm: Remove flush_xen_text_tlb_local()
Date: Fri, 26 Apr 2019 16:50:16 +0300	[thread overview]
Message-ID: <4e365b84-122d-e613-ceaa-e2df8c865262@gmail.com> (raw)
Message-ID: <20190426135016.2YgTm8DA0rPREpcqRo0hrhhiviz9ykFZ1CrYjpWSF-8@z> (raw)
In-Reply-To: <fb22f2a1-f3a6-a962-a9ba-54c22e5c7d2a@arm.com>



On 25.04.19 23:37, Julien Grall wrote:
> The understanding is correct. I am not entirely sure how I can improve
> the comment.
I've re-read the comment again, and realized it actually fits. So let it be.

> 
> To be honest, I am not entirely sure whether the isb() is necessary
> here. At worst, an entry of an existing mappings is not cached with the
> SCTLR_EL2.WXN set. This may only defer the problem is an entry is
> incorrectly configured before the flush. This is done early at boot (and
> will be done much earlier in [1]).Well, following this logic we may finish with TLB flush is not needed here at all. Because entries, already reached TLB, were configured before, and are believed valid. All the next will have WXN set.
But in this case, ISB is needed as an exact point from which all new TLB entries will have WXN.

> So I am kind of tempted to drop the
> isb() here.

-- 
Sincerely,
Andrii Anisov.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel

  reply	other threads:[~2019-04-26 13:50 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-17 17:58 [PATCH 0/7] xen/arm: TLB flush helpers rework Julien Grall
2019-04-17 17:58 ` [Xen-devel] " Julien Grall
2019-04-17 17:58 ` [PATCH 1/7] xen/arm: mm: Consolidate setting SCTLR_EL2.WXN in a single place Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:00   ` Andrii Anisov
2019-04-25 18:00     ` [Xen-devel] " Andrii Anisov
2019-04-25 20:26     ` Julien Grall
2019-04-25 20:26       ` [Xen-devel] " Julien Grall
2019-04-26 13:48       ` Andrii Anisov
2019-04-26 13:48         ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 2/7] xen/arm: Remove flush_xen_text_tlb_local() Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:00   ` Andrii Anisov
2019-04-25 18:00     ` [Xen-devel] " Andrii Anisov
2019-04-25 20:37     ` Julien Grall
2019-04-25 20:37       ` [Xen-devel] " Julien Grall
2019-04-26 13:50       ` Andrii Anisov [this message]
2019-04-26 13:50         ` Andrii Anisov
2019-04-26 14:15         ` Andrii Anisov
2019-04-26 14:15           ` [Xen-devel] " Andrii Anisov
2019-04-26 14:31           ` Julien Grall
2019-04-26 14:31             ` [Xen-devel] " Julien Grall
2019-04-26 15:08             ` Andrii Anisov
2019-04-26 15:08               ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 3/7] xen/arm: tlbflush: Clarify the TLB helpers name Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:00   ` Andrii Anisov
2019-04-25 18:00     ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 4/7] xen/arm: page: Clarify the Xen TLBs " Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:00   ` Andrii Anisov
2019-04-25 18:00     ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 5/7] xen/arm: Gather all TLB flush helpers in tlbflush.h Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:01   ` Andrii Anisov
2019-04-25 18:01     ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 6/7] xen/arm: tlbflush: Rework TLB helpers Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:01   ` Andrii Anisov
2019-04-25 18:01     ` [Xen-devel] " Andrii Anisov
2019-04-25 20:42     ` Julien Grall
2019-04-25 20:42       ` [Xen-devel] " Julien Grall
2019-04-26 13:49       ` Andrii Anisov
2019-04-26 13:49         ` [Xen-devel] " Andrii Anisov
2019-04-26 14:06         ` Julien Grall
2019-04-26 14:06           ` [Xen-devel] " Julien Grall
2019-04-26 15:17           ` Andrii Anisov
2019-04-26 15:17             ` [Xen-devel] " Andrii Anisov
2019-04-17 17:58 ` [PATCH 7/7] xen/arm: mm: Flush the TLBs even if a mapping failed in create_xen_entries Julien Grall
2019-04-17 17:58   ` [Xen-devel] " Julien Grall
2019-04-25 18:03   ` Andrii Anisov
2019-04-25 18:03     ` [Xen-devel] " Andrii Anisov

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