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From: Baoquan He <bhe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
	mingo@redhat.com, dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, linux-mm@kvack.org,
	akpm@linux-foundation.org, hch@lst.de, robin.murphy@arm.com,
	cl@linux.com, penberg@kernel.org, rientjes@google.com,
	iamjoonsoo.kim@lge.com, vbabka@suse.cz, m.szyprowski@samsung.com,
	John.p.donnelly@oracle.com, kexec@lists.infradead.org,
	rppt@linux.ibm.com
Subject: Re: [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages
Date: Mon, 13 Dec 2021 22:03:48 +0800	[thread overview]
Message-ID: <20211213140348.GA26562@MiWiFi-R3L-srv> (raw)
In-Reply-To: <YbdJ00wRFvi0aqze@zn.tnic>

On 12/13/21 at 02:25pm, Borislav Petkov wrote:
> On Tue, Dec 07, 2021 at 11:16:31AM +0800, Baoquan He wrote:
> > > This low 1M lock down is needed because AMD SME encrypts memory making
> > > the old backup region mechanims impossible when switching into kdump
> > > kernel. And Intel engineer mentioned their TDX (Trusted domain extensions)
> > > which is under development in kernel also needs lock down the low 1M.
> > > So we can't simply revert above commits to fix the page allocation
> > > failure from DMA zone as someone suggested.
> 
> Did you read
> 
>   f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM")
> 
> carefully for a more generically important reason as to why the first 1M
> should not be used?

Apparently I didn't. I slacked off and just grabbed things stored in my
brain. This is the right justification and missed. Thanks for pointing
it out.


WARNING: multiple messages have this Message-ID (diff)
From: Baoquan He <bhe@redhat.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de,
	mingo@redhat.com, dave.hansen@linux.intel.com, luto@kernel.org,
	peterz@infradead.org, linux-mm@kvack.org,
	akpm@linux-foundation.org, hch@lst.de, robin.murphy@arm.com,
	cl@linux.com, penberg@kernel.org, rientjes@google.com,
	iamjoonsoo.kim@lge.com, vbabka@suse.cz, m.szyprowski@samsung.com,
	John.p.donnelly@oracle.com, kexec@lists.infradead.org,
	rppt@linux.ibm.com
Subject: Re: [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages
Date: Mon, 13 Dec 2021 22:03:48 +0800	[thread overview]
Message-ID: <20211213140348.GA26562@MiWiFi-R3L-srv> (raw)
In-Reply-To: <YbdJ00wRFvi0aqze@zn.tnic>

On 12/13/21 at 02:25pm, Borislav Petkov wrote:
> On Tue, Dec 07, 2021 at 11:16:31AM +0800, Baoquan He wrote:
> > > This low 1M lock down is needed because AMD SME encrypts memory making
> > > the old backup region mechanims impossible when switching into kdump
> > > kernel. And Intel engineer mentioned their TDX (Trusted domain extensions)
> > > which is under development in kernel also needs lock down the low 1M.
> > > So we can't simply revert above commits to fix the page allocation
> > > failure from DMA zone as someone suggested.
> 
> Did you read
> 
>   f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM")
> 
> carefully for a more generically important reason as to why the first 1M
> should not be used?

Apparently I didn't. I slacked off and just grabbed things stored in my
brain. This is the right justification and missed. Thanks for pointing
it out.


_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

  reply	other threads:[~2021-12-13 14:04 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-07  3:07 [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages Baoquan He
2021-12-07  3:07 ` Baoquan He
2021-12-07  3:07 ` [PATCH RESEND v2 1/5] docs: kernel-parameters: Update to reflect the current default size of atomic pool Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:53   ` John Donnelly
2021-12-07  3:53     ` John Donnelly
2021-12-07  3:07 ` [PATCH RESEND v2 2/5] dma-pool: allow user to disable " Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:53   ` John Donnelly
2021-12-07  3:53     ` John Donnelly
2021-12-13  7:44   ` Christoph Hellwig
2021-12-13  7:44     ` Christoph Hellwig
2021-12-13  8:16     ` Baoquan He
2021-12-13  8:16       ` Baoquan He
2021-12-07  3:07 ` [PATCH RESEND v2 3/5] mm_zone: add function to check if managed dma zone exists Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:53   ` John Donnelly
2021-12-07  3:53     ` John Donnelly
2021-12-07 11:23   ` David Hildenbrand
2021-12-07 11:23     ` David Hildenbrand
2021-12-09 13:02     ` Baoquan He
2021-12-09 13:02       ` Baoquan He
2021-12-09 13:10       ` David Hildenbrand
2021-12-09 13:10         ` David Hildenbrand
2021-12-09 13:23         ` Baoquan He
2021-12-09 13:23           ` Baoquan He
2021-12-07  3:07 ` [PATCH RESEND v2 4/5] dma/pool: create dma atomic pool only if dma zone has managed pages Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:54   ` John Donnelly
2021-12-07  3:54     ` John Donnelly
2021-12-07  3:54     ` John Donnelly
2021-12-07  3:07 ` [PATCH RESEND v2 5/5] mm/slub: do not create dma-kmalloc if no managed pages in DMA zone Baoquan He
2021-12-07  3:07   ` Baoquan He
2021-12-07  3:54   ` John Donnelly
2021-12-07  3:54     ` John Donnelly
2021-12-07  3:16 ` [PATCH RESEND v2 0/5] Avoid requesting page from DMA zone when no managed pages Baoquan He
2021-12-07  3:16   ` Baoquan He
2021-12-07  4:03   ` John Donnelly
2021-12-07  4:03     ` John Donnelly
2021-12-08  4:33     ` Andrew Morton
2021-12-08  4:33       ` Andrew Morton
2021-12-08  4:56       ` John Donnelly
2021-12-08  4:56         ` John Donnelly
2021-12-13  3:54     ` Baoquan He
2021-12-13  3:54       ` Baoquan He
2021-12-13 13:25   ` Borislav Petkov
2021-12-13 13:25     ` Borislav Petkov
2021-12-13 14:03     ` Baoquan He [this message]
2021-12-13 14:03       ` Baoquan He
2021-12-07  8:05 ` Christoph Lameter
2021-12-07  8:05   ` Christoph Lameter
2021-12-09  8:05   ` Baoquan He
2021-12-09  8:05     ` Baoquan He
2021-12-09 12:59     ` Christoph Lameter
2021-12-09 12:59       ` Christoph Lameter
2021-12-13  7:39       ` Baoquan He
2021-12-13  7:39         ` Baoquan He
2021-12-13  7:49         ` Christoph Hellwig
2021-12-13  7:49           ` Christoph Hellwig
2021-12-13 14:21       ` Hyeonggon Yoo
2021-12-13 14:21         ` Hyeonggon Yoo
2021-12-13  7:47   ` Christoph Hellwig
2021-12-13  7:47     ` Christoph Hellwig

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