From: Dave Hansen <dave.hansen@intel.com>
To: Tom Lendacky <thomas.lendacky@amd.com>,
Adam Dunlap <acdunlap@google.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
David Hildenbrand <david@redhat.com>,
Mike Rapoport <rppt@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Nikunj A Dadhania <nikunj@amd.com>,
Dionna Glaze <dionnaglaze@google.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Joerg Roedel <jroedel@suse.de>, Jacob Xu <jacobhxu@google.com>
Subject: Re: [PATCH] x86/sev-es: Do not use copy_from_kernel_nofault in early #VC handler
Date: Fri, 8 Sep 2023 07:48:58 -0700 [thread overview]
Message-ID: <cc90c896-7581-62b5-4836-971e9ca8fac0@intel.com> (raw)
In-Reply-To: <0d8a35c9-82ca-188a-529d-65fd01c40149@amd.com>
On 9/8/23 06:13, Tom Lendacky wrote:
> On 9/7/23 14:12, Dave Hansen wrote:
>> But seriously, is it even *possible* to spin up a SEV-SNP VM what
>> doesn't have NX?
>
> It is a common path, so while an SEV guest would have NX support, you
> would first have to determine that it is an SEV guest. That would take
> issuing a CPUID instruction in order to determine if a particular MSR
> can be read...
I was thinking more along the lines of telling folks that if they want
to turn SEV-SNP support on, they also have to give up on running on a
!NX system. That would be a _bit_ nicer than just refusing to boot on
all !NX systems.
> Ultimately, we could probably pass the encryption mask from the
> decompressor to the kernel and avoid some of the checks during early
> boot of the kernel proper. Is it possible to boot an x86 kernel without
> going through the decompressor?
I think it's possible, but it's very unusual.
next prev parent reply other threads:[~2023-09-08 14:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-06 22:45 [PATCH] x86/sev-es: Do not use copy_from_kernel_nofault in early #VC handler Adam Dunlap
2023-09-06 23:01 ` Dave Hansen
2023-09-06 23:25 ` Adam Dunlap
2023-09-07 17:04 ` Dave Hansen
2023-09-07 18:03 ` Adam Dunlap
2023-09-07 19:12 ` Dave Hansen
2023-09-07 22:30 ` Adam Dunlap
2023-09-07 22:45 ` Dave Hansen
2023-09-08 13:13 ` Tom Lendacky
2023-09-08 14:48 ` Dave Hansen [this message]
2023-09-08 15:13 ` Peter Zijlstra
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