From: Andi Kleen <ak@linux.intel.com>
To: Erdem Aktas <erdemaktas@google.com>
Cc: Andy Lutomirski <luto@kernel.org>, Joerg Roedel <jroedel@suse.de>,
David Rientjes <rientjes@google.com>,
Borislav Petkov <bp@alien8.de>,
Sean Christopherson <seanjc@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Jon Grimm <jon.grimm@amd.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
"Kaplan, David" <David.Kaplan@amd.com>,
Varad Gautam <varad.gautam@suse.com>,
Dario Faggioli <dfaggioli@suse.com>, x86 <x86@kernel.org>,
linux-mm@kvack.org, linux-coco@lists.linux.dev
Subject: Re: Runtime Memory Validation in Intel-TDX and AMD-SNP
Date: Tue, 20 Jul 2021 17:38:54 -0700 [thread overview]
Message-ID: <20210721003854.GD535804@tassilo.jf.intel.com> (raw)
In-Reply-To: <CAAYXXYxfpc8ix2dWzsPJ8Ew-fHROKm+WYLemjD1U8cTqzy6BHQ@mail.gmail.com>
> > > >> Also in general i don't think it will really happen, at least
> > > initially.
> > > >> All the shared buffers we use are allocated and never freed. So such a
> > > >> problem could be deferred.
> > >
> > > Does it not depend on kernel configs? Currently, there is a valid
> > > control path in dma_alloc_coherent which might alloc and free shared
> > > pages.
> >
> > If the device filter is active it won't.
> >
>
> If I am not missing something, I do not see that the device filter
> checks for CONFIG_DMA_COHERENT_POOL and if it is not enabled,
> dma_alloc_coherent will allocate a regular memory, convert it to
> shared and convert it back to private when it is freed.
What I meant is that the only devices that will be supported (mainly
virtio) initially don't ever free coherent memory
And the device filter enforces that.
Now we probably want to support freeing anyways just to be able to run
without device filter, but it definitely doesn't have to be fast
or efficient. If there's a problem with it it would be a quite reasonable
implementation to keep it in a pool.
-Andi
next prev parent reply other threads:[~2021-07-21 0:38 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 12:58 Runtime Memory Validation in Intel-TDX and AMD-SNP Joerg Roedel
2021-07-19 13:07 ` Matthew Wilcox
2021-07-19 15:02 ` Joerg Roedel
2021-07-19 20:39 ` Andi Kleen
2021-07-20 8:55 ` Joerg Roedel
2021-07-20 9:34 ` Dr. David Alan Gilbert
2021-07-20 11:50 ` Joerg Roedel
2021-07-20 0:26 ` Andy Lutomirski
[not found] ` <CAAYXXYwFzrf8uY-PFkMRSG28+HztfGdJft8kB3Y3keWCx9K8TQ@mail.gmail.com>
2021-07-20 2:00 ` Erdem Aktas
2021-07-20 5:17 ` Andi Kleen
2021-07-20 9:11 ` Joerg Roedel
2021-07-20 17:32 ` Andi Kleen
2021-07-20 23:09 ` Erdem Aktas
2021-07-21 0:38 ` Andi Kleen [this message]
2021-07-22 17:31 ` Marc Orr
2021-07-26 18:55 ` Joerg Roedel
[not found] ` <eacb9c1f-2c61-4a7f-b5a3-7bf579e6cbf6@www.fastmail.com>
2021-07-20 19:54 ` Erdem Aktas
2021-07-20 22:01 ` Andi Kleen
2021-07-20 23:55 ` Erdem Aktas
2021-07-21 0:35 ` Andi Kleen
2021-07-21 8:51 ` Joerg Roedel
2021-07-20 8:44 ` Joerg Roedel
2021-07-20 14:14 ` Dave Hansen
2021-07-20 17:30 ` Kirill A. Shutemov
2021-07-21 9:20 ` Mike Rapoport
2021-07-21 10:02 ` Kirill A. Shutemov
2021-07-21 10:22 ` Mike Rapoport
2021-07-21 10:53 ` Joerg Roedel
2021-07-21 9:25 ` Joerg Roedel
2021-07-21 10:25 ` Kirill A. Shutemov
2021-07-21 10:48 ` Joerg Roedel
2021-07-22 15:46 ` David Hildenbrand
2021-07-26 19:02 ` Joerg Roedel
2021-07-27 9:34 ` David Hildenbrand
2021-08-02 10:19 ` Joerg Roedel
2021-08-02 18:47 ` David Hildenbrand
2021-07-22 15:57 ` David Hildenbrand
2021-07-22 19:51 ` Kirill A. Shutemov
2021-07-23 15:23 ` Mike Rapoport
2021-07-23 16:29 ` Kirill A. Shutemov
2021-07-25 9:16 ` Mike Rapoport
2021-07-25 18:28 ` Kirill A. Shutemov
2021-07-26 10:00 ` Mike Rapoport
2021-07-26 11:53 ` Kirill A. Shutemov
2021-07-26 19:13 ` Joerg Roedel
2021-07-26 23:02 ` Erdem Aktas
2021-07-26 23:54 ` Kirill A. Shutemov
2021-07-27 1:35 ` Erdem Aktas
2021-07-23 11:04 ` Varad Gautam
2021-07-23 14:34 ` Kaplan, David
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