Re: [PATCH v2 2/6] target/i386/sev: Add kernel hashes only if sev-guest.kernel-hashes=on

[Daniel P . Berrangé]

On Mon, Nov 08, 2021 at 01:48:36PM +0000, Dov Murik wrote:
> Commit cff03145ed3c ("sev/i386: Introduce sev_add_kernel_loader_hashes
> for measured linux boot", 2021-09-30) introduced measured direct boot
> with -kernel, using an OVMF-designated hashes table which QEMU fills.
> 
> However, if OVMF doesn't designate such an area, QEMU would completely
> abort the VM launch.  This breaks launching with -kernel using older
> OVMF images which don't publish the SEV_HASH_TABLE_RV_GUID.
> 
> Fix that so QEMU will only look for the hashes table if the sev-guest
> kernel-hashes option is set to on.  Otherwise, QEMU won't look for the
> designated area in OVMF and won't fill that area.
> 
> To enable addition of kernel hashes, launch the guest with:
> 
>     -object sev-guest,...,kernel-hashes=on
> 
> Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
> Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  target/i386/sev.c | 8 ++++++++
>  1 file changed, 8 insertions(+)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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