From: Dov Murik <dovmurik@linux.ibm.com>
To: Borislav Petkov <bp@suse.de>
Cc: linux-efi@vger.kernel.org, Ashish Kalra <ashish.kalra@amd.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Ard Biesheuvel <ardb@kernel.org>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Andi Kleen <ak@linux.intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Andrew Scull <ascull@google.com>,
Dave Hansen <dave.hansen@intel.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>,
Lenny Szubowicz <lszubowi@redhat.com>,
Peter Gonda <pgonda@google.com>,
Matthew Garrett <mjg59@srcf.ucam.org>,
James Bottomley <jejb@linux.ibm.com>,
Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
Jim Cadden <jcadden@ibm.com>,
Daniele Buono <dbuono@linux.vnet.ibm.com>,
linux-coco@lists.linux.dev,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Dov Murik <dovmurik@linux.ibm.com>
Subject: Re: [PATCH v8 0/4] Allow guest access to EFI confidential computing secret area
Date: Wed, 30 Mar 2022 09:11:54 +0300 [thread overview]
Message-ID: <247080bd-fef5-c892-7753-f9b7cf650166@linux.ibm.com> (raw)
In-Reply-To: <7696ba46-91c7-7119-bd68-b3521459cf37@linux.ibm.com>
On 29/03/2022 23:28, Dov Murik wrote:
>
>
> On 29/03/2022 21:30, Borislav Petkov wrote:
>
>>
>> So now that I think of it, it would be even nicer if the fact whether
>> guest debugging is allowed, were available to the guest *very early*
>> during boot. Because I think the most important cases where you'd want
>> to singlestep a SEV* guest with the qemu gdbstub is early guest kernel
>> boot code. So it would be cool if we'd have access to the debugging
>> setting that early.
>>
>> Lemme have a look at your patches in detail to get an idea what's
>> happening there.
>
After a night's sleep I figured out that an SEV guest cannot tell if a
value it's reading was (a) encrypted by the host using
KVM_SEV_LAUNCH_UPDATE_DATA, or (b) added using secret injection using
KVM_SEV_LAUNCH_SECRET.
The only difference is that if the host is using
KVM_SEV_LAUNCH_UPDATE_DATA, then it changes the measurement. But maybe
for debugging scenarios we (= Guest Owner) don't care about the
measurement being correct.
If that's the case, we don't need a secure channel and secret injection.
You can use a simple "sev=debug" (or whatever) in the kernel
command-line to indicate your needs.
Did I miss something?
-Dov
next prev parent reply other threads:[~2022-03-30 6:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-28 11:42 [PATCH v8 0/4] Allow guest access to EFI confidential computing secret area Dov Murik
2022-02-28 11:42 ` [PATCH v8 1/4] efi: Save location of EFI confidential computing area Dov Murik
2022-02-28 11:42 ` [PATCH v8 2/4] virt: Add efi_secret module to expose confidential computing secrets Dov Murik
2022-03-01 12:24 ` Gerd Hoffmann
2022-02-28 11:42 ` [PATCH v8 3/4] efi: Load efi_secret module if EFI secret area is populated Dov Murik
2022-02-28 12:49 ` Ard Biesheuvel
2022-02-28 13:06 ` Dov Murik
2022-02-28 13:15 ` Ard Biesheuvel
2022-03-31 9:04 ` Dov Murik
2022-04-12 13:08 ` Ard Biesheuvel
2022-04-12 13:18 ` Dov Murik
2022-02-28 11:42 ` [PATCH v8 4/4] docs: security: Add secrets/coco documentation Dov Murik
2022-03-24 16:33 ` [PATCH v8 0/4] Allow guest access to EFI confidential computing secret area Borislav Petkov
2022-03-29 12:55 ` Dov Murik
2022-03-29 18:30 ` Borislav Petkov
2022-03-29 20:28 ` Dov Murik
2022-03-30 6:11 ` Dov Murik [this message]
2022-03-31 9:19 ` Borislav Petkov
2022-03-31 21:05 ` Dov Murik
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