Re: [PATCH v3 0/2] x86/sev: Measured Linux SEV guest with kernel/initrd/cmdline

[Philippe Mathieu-Daudé]

On 7/8/21 6:41 PM, Connor Kuehl wrote:
> Hi Paolo,
> 
> Please consider this series[1] for inclusion into your next pull request.
> 
> Just a note that this series has a companion series that is getting
> upstreamed into OVMF[2]

Shouldn't we get the OVMF part merged first?

> 
> [1] Patchwork link, if convenient: 
> https://patchwork.kernel.org/project/qemu-devel/cover/20210624102040.2015280-1-dovmurik@linux.ibm.com/
> [2] https://bugzilla.tianocore.org/show_bug.cgi?id=3457#c6
> 
> Thank you,
> 
> Connor
> 
> On 6/24/21 3:20 AM, Dov Murik wrote:
>> Currently booting with -kernel/-initrd/-append is not supported in SEV
>> confidential guests, because the content of these blobs is not measured
>> and therefore not trusted by the SEV guest.
>>
>> However, in some cases the kernel, initrd, and cmdline are not secret
>> but should not be modified by the host.  In such a case, we want to
>> verify inside the trusted VM that the kernel, initrd, and cmdline are
>> indeed the ones expected by the Guest Owner, and only if that is the
>> case go on and boot them up (removing the need for grub inside OVMF in
>> that mode).
>>
>> To support that, OVMF adds a special area for hashes of
>> kernel/initrd/cmdline; that area is expected to be filled by QEMU and
>> encrypted as part of the initial SEV guest launch.  This in turn makes
>> the hashes part of the PSP measured content, and OVMF can trust these
>> inputs if they match the hashes.
>>
>> This series adds an SEV function to generate the table of hashes for
>> OVMF and encrypt it (patch 1/2), and calls this function if SEV is
>> enabled when the kernel/initrd/cmdline are prepared (patch 2/2).
>>
>> Corresponding OVMF support was submitted to edk2-devel [1] (patch series
>> "Measured SEV boot with kernel/initrd/cmdline"); it's still under
>> review.
>>
>> [1] https://edk2.groups.io/g/devel/topic/patch_v1_0_8_measured_sev/83074450
>>
>> ---