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From: Conor Dooley <conor@kernel.org>
To: Song Shuai <songshuaishuai@tinylab.org>
Cc: paul.walmsley@sifive.com, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, robh+dt@kernel.org,
	frowand.list@gmail.com, ajones@ventanamicro.com,
	alexghiti@rivosinc.com, mpe@ellerman.id.au, arnd@arndb.de,
	rppt@kernel.org, samuel@sholland.org, panqinglin2020@iscas.ac.cn,
	conor.dooley@microchip.com, anup@brainfault.org,
	xianting.tian@linux.alibaba.com, anshuman.khandual@arm.com,
	heiko@sntech.de, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH V1 0/3] Revert huge-paged linear mapping and its related fixups
Date: Sun, 25 Jun 2023 15:16:55 +0100	[thread overview]
Message-ID: <20230625-squire-hulk-d28483ab5ef7@spud> (raw)
In-Reply-To: <20230625140931.1266216-1-songshuaishuai@tinylab.org>


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On Sun, Jun 25, 2023 at 10:09:28PM +0800, Song Shuai wrote:
> We have encountered these two issues about huge-paged linear mapping since v6.4-rc1: 
> 
> 1. Bug report: kernel paniced when system hibernates[1]
>   
> OpenSbi [v0.8,v1.3) set the PMP regions as !no-map, and the commit 3335068f8721 
> ("riscv: Use PUD/P4D/PGD pages for the linear mapping") mapped them in linear mapping.
> The hibernation process attempted to save/restore these mapped regions resulting in access fault.
> 
> This issue was temporarily fixed by commit ed309ce52218 ("RISC-V: mark hibernation as nonportable").
> But as Alex's RFC and Rob's response stats in another thread [2] , 
> "Hibernation is only one case. Speculative accesses could also occur."
> So this fixing commit seems not the perfect answer to this issue.

This is a misunderstanding, I was not attempting to fix the issue, but
rather buy time to fix the problem properly, without regressing support
for hibernation when we do.

Cheers,
Conor.


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WARNING: multiple messages have this Message-ID (diff)
From: Conor Dooley <conor@kernel.org>
To: Song Shuai <songshuaishuai@tinylab.org>
Cc: paul.walmsley@sifive.com, palmer@dabbelt.com,
	aou@eecs.berkeley.edu, robh+dt@kernel.org,
	frowand.list@gmail.com, ajones@ventanamicro.com,
	alexghiti@rivosinc.com, mpe@ellerman.id.au, arnd@arndb.de,
	rppt@kernel.org, samuel@sholland.org, panqinglin2020@iscas.ac.cn,
	conor.dooley@microchip.com, anup@brainfault.org,
	xianting.tian@linux.alibaba.com, anshuman.khandual@arm.com,
	heiko@sntech.de, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH V1 0/3] Revert huge-paged linear mapping and its related fixups
Date: Sun, 25 Jun 2023 15:16:55 +0100	[thread overview]
Message-ID: <20230625-squire-hulk-d28483ab5ef7@spud> (raw)
In-Reply-To: <20230625140931.1266216-1-songshuaishuai@tinylab.org>

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On Sun, Jun 25, 2023 at 10:09:28PM +0800, Song Shuai wrote:
> We have encountered these two issues about huge-paged linear mapping since v6.4-rc1: 
> 
> 1. Bug report: kernel paniced when system hibernates[1]
>   
> OpenSbi [v0.8,v1.3) set the PMP regions as !no-map, and the commit 3335068f8721 
> ("riscv: Use PUD/P4D/PGD pages for the linear mapping") mapped them in linear mapping.
> The hibernation process attempted to save/restore these mapped regions resulting in access fault.
> 
> This issue was temporarily fixed by commit ed309ce52218 ("RISC-V: mark hibernation as nonportable").
> But as Alex's RFC and Rob's response stats in another thread [2] , 
> "Hibernation is only one case. Speculative accesses could also occur."
> So this fixing commit seems not the perfect answer to this issue.

This is a misunderstanding, I was not attempting to fix the issue, but
rather buy time to fix the problem properly, without regressing support
for hibernation when we do.

Cheers,
Conor.


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  parent reply	other threads:[~2023-06-25 14:17 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-25 14:09 [PATCH V1 0/3] Revert huge-paged linear mapping and its related fixups Song Shuai
2023-06-25 14:09 ` Song Shuai
2023-06-25 14:09 ` [PATCH V1 1/3] Revert "RISC-V: mark hibernation as nonportable" Song Shuai
2023-06-25 14:09   ` Song Shuai
2023-06-25 14:18   ` Conor Dooley
2023-06-25 14:18     ` Conor Dooley
2023-06-25 15:09     ` Song Shuai
2023-06-25 15:09       ` Song Shuai
2023-06-25 22:15       ` Conor Dooley
2023-06-25 22:15         ` Conor Dooley
2023-06-25 22:36         ` Palmer Dabbelt
2023-06-25 22:36           ` Palmer Dabbelt
2023-06-26 13:34           ` Conor Dooley
2023-06-26 13:34             ` Conor Dooley
2023-06-26 14:43             ` Palmer Dabbelt
2023-06-26 14:43               ` Palmer Dabbelt
2023-06-26 15:44               ` Conor Dooley
2023-06-26 15:44                 ` Conor Dooley
2023-06-25 14:09 ` [PATCH V1 2/3] Revert "riscv: Check the virtual alignment before choosing a map size" Song Shuai
2023-06-25 14:09   ` Song Shuai
2023-06-25 14:16 ` Conor Dooley [this message]
2023-06-25 14:16   ` [PATCH V1 0/3] Revert huge-paged linear mapping and its related fixups Conor Dooley
2023-06-25 15:28 ` [PATCH V1 3/3] Revert "riscv: Use PUD/P4D/PGD pages for the linear mapping" Song Shuai
2023-06-25 15:28   ` Song Shuai
2023-06-25 20:36 ` [PATCH V1 0/3] Revert huge-paged linear mapping and its related fixups Alexandre Ghiti
2023-06-25 20:36   ` Alexandre Ghiti
2023-06-27 11:47   ` Alexandre Ghiti
2023-06-27 11:47     ` Alexandre Ghiti
2023-06-27 15:13     ` Song Shuai
2023-06-27 15:13       ` Song Shuai
2023-06-28 11:39       ` Alexandre Ghiti
2023-06-28 11:39         ` Alexandre Ghiti

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