Re: [RFC 06/16] KVM: selftests: add library for creating/interacting with SEV guests

From: Tom Lendacky <thomas.lendacky@amd.com>
To: Mingwei Zhang <mizhang@google.com>, Michael Roth <Michael.Roth@amd.com>
Cc: Marc Orr <marcorr@google.com>,
	linux-kselftest@vger.kernel.org, kvm list <kvm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
	Nathan Tempelman <natet@google.com>,
	Steve Rutherford <srutherford@google.com>,
	Sean Christopherson <seanjc@google.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Varad Gautam <varad.gautam@suse.com>,
	Shuah Khan <shuah@kernel.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	David Woodhouse <dwmw@amazon.co.uk>,
	Ricardo Koller <ricarkol@google.com>,
	Jim Mattson <jmattson@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Joerg Roedel <joro@8bytes.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	"H . Peter Anvin" <hpa@zytor.com>
Subject: Re: [RFC 06/16] KVM: selftests: add library for creating/interacting with SEV guests
Date: Thu, 4 Nov 2021 08:44:09 -0500	[thread overview]
Message-ID: <9c3f6936-77d6-7c32-059c-2e998f0c67b2@amd.com> (raw)
In-Reply-To: <CAL715WKBBXNpJFK-3254ox_GU=v04RdYC=uXu4S5kbf=1R9aYA@mail.gmail.com>

On 11/4/21 12:25 AM, Mingwei Zhang wrote:
>>
>>>
>>>> +#define SEV_FW_REQ_VER_MAJOR   1
>>>> +#define SEV_FW_REQ_VER_MINOR   30
>>>
>>> Where does the requirement for this minimum version come from? Maybe
>>> add a comment?
>>>
>>> Edit: Is this for patches later on in the series that exercise SNP? If
>>> so, I think it would be better to add a check like this in the test
>>> itself, rather than globally. I happened to test this on a machine
>>> with a very old PSP FW, 0.22, and the SEV test added in patch #7 seems
>>> to work fine with this ancient PSP FW.
>>
>> Ah, yes, this was mostly for SNP support. I'll implement a separate minimum
>> version for SEV/SEV-ES.
>>
> 
> I want to ask the same thing, I tried to run the sev selftest today
> and I was blocked by this minimum version number... BTW: I suspect if
> I want to update the SEV firmware I have to update the BIOS myself?

The SEV firmware is updatable at module load time through the
DOWNLOAD_FIRMWARE command.

> So, it would be good to know what is the actual minimum for SEV.
> 
> In addition, maybe that's side effect, I see a warning when building the kernel:
> 
> "module ccp.ko requires firmware amd/amd_sev_fam19h_model0xh.sbin"

The firmware images reside (typically) in /lib/firmware/amd/. There is a
new version for fam19h that you can copy into that directory at:

https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/amd

or

https://developer.amd.com/sev/ under the Links & Downloads section (Note,
if retrieved from here you will/may need to rename the .sbin file to match
the name mentioned above).

> 
> Maybe I need some hints from you? Or maybe it is just harmless. I did
> double checked and it looks like I was using either
> amd_sev_fam17h_model3xh.sbin or amd_sev_fam17h_model0xh.sbin

If you're on a fam19h machine, the fam17h builds won't be used.

Thanks,
Tom

> 
> Thanks.
> -Mingwei
> 