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From: Peter Zijlstra <peterz@infradead.org>
To: Joerg Roedel <jroedel@suse.de>
Cc: David Rientjes <rientjes@google.com>,
	Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Andi Kleen <ak@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>,
	Christoph Hellwig <hch@lst.de>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Ingo Molnar <mingo@redhat.com>,
	x86@kernel.org, linux-mm@kvack.org
Subject: Re: AMD SEV-SNP/Intel TDX: validation of memory pages
Date: Fri, 12 Feb 2021 16:19:22 +0100	[thread overview]
Message-ID: <YCacenGvoQsTmVcy@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210212145318.GK5453@suse.de>

On Fri, Feb 12, 2021 at 03:53:18PM +0100, Joerg Roedel wrote:
> On Fri, Feb 12, 2021 at 03:17:57PM +0100, Peter Zijlstra wrote:
> > On Fri, Feb 12, 2021 at 02:19:07PM +0100, Joerg Roedel wrote:
> > > 	- Then we can pass this information up the boot process by
> > > 	  extending struct boot_params. The bootloader can pass which
> > > 	  E820 usable memory it validated, same for the kernel
> > > 	  decompressor. The text+data (but not bss) of the running
> > > 	  kernel image is per definition validated by the decompressor
> > > 	  and does not need to be added explicitly to boot_params.
> > 
> > Even if all text+data is prevalidated, we'll probably still need some
> > prevalidated bss and certainly some prevalidated percpu data (like the
> > various stacks, but also crud like the percpu variable we store the DR7
> > shadow in etc..).
> 
> The kernel sets up early exception handling in head_64.S, right after
> setting MSR_GS_BASE. So per-cpu data can probably be be on-demand. For
> bss you might be right.

That's the thing, we don't want #VE to happen in noinstr code *ever*.

noinstr covers the whole entry code, things like the syscall gap and nmi
recursion setup. Getting a #VE there is fail.

So most per-cpu data can be on-demand, but some of it must absolutely
not be.


  reply	other threads:[~2021-02-12 15:19 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02  1:51 AMD SEV-SNP/Intel TDX: validation of memory pages David Rientjes
2021-02-02 13:17 ` Matthew Wilcox
2021-02-02 16:02 ` Kirill A. Shutemov
2021-02-03  0:16   ` Brijesh Singh
2021-02-11 17:46     ` Sean Christopherson
2021-02-02 22:37 ` Andi Kleen
2021-02-11 20:46 ` Peter Zijlstra
2021-02-12 13:19 ` Joerg Roedel
2021-02-12 14:17   ` Peter Zijlstra
2021-02-12 14:53     ` Joerg Roedel
2021-02-12 15:19       ` Peter Zijlstra [this message]
2021-02-12 15:28         ` Joerg Roedel
2021-02-12 16:12           ` Peter Zijlstra
2021-02-12 16:18             ` Joerg Roedel
2021-02-12 16:45               ` Peter Zijlstra
2021-02-12 17:48                 ` Dave Hansen
2021-02-12 18:22                   ` Sean Christopherson
2021-02-12 18:38                     ` Andy Lutomirski
2021-02-12 18:43                       ` Sean Christopherson
2021-02-12 18:46                     ` Dave Hansen
2021-02-12 19:24                       ` Sean Christopherson
2021-02-16 10:00                 ` Joerg Roedel
2021-02-16 14:27                   ` Andi Kleen
2021-02-16 14:46                     ` Peter Zijlstra
2021-02-16 15:59                       ` Paolo Bonzini
2021-02-16 16:25                         ` Joerg Roedel
2021-02-16 16:48                           ` Paolo Bonzini
2021-02-16 18:26                             ` Joerg Roedel
2021-02-16 18:33                               ` Paolo Bonzini
2021-02-16 16:47                         ` Peter Zijlstra
2021-02-16 16:57                         ` Andy Lutomirski
2021-02-16 17:05                           ` Paolo Bonzini
2021-02-16 16:55                       ` Andi Kleen
2021-02-12 21:42             ` Andi Kleen
2021-02-12 21:58               ` Peter Zijlstra
2021-02-12 22:39                 ` Andi Kleen
2021-02-12 22:46                   ` Andy Lutomirski
2021-02-13  9:38                   ` Peter Zijlstra
2021-02-12 23:51                 ` Paolo Bonzini
2021-03-23  9:33 ` Joerg Roedel

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