linux-kernel - Re: [PATCH v6 2/9] KVM: SEV: Disable SEV on platform init failure

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Message-ID: <0b99e313-cf5a-46ef-b82c-a813eeb31f4d@amd.com>
Date: Fri, 14 Feb 2025 12:09:13 -0600
From: Pratik Rajesh Sampat <prsampat@....com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org,
 linux-crypto@...r.kernel.org, linux-kselftest@...r.kernel.org,
 pbonzini@...hat.com, thomas.lendacky@....com, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
 shuah@...nel.org, pgonda@...gle.com, ashish.kalra@....com, nikunj@....com,
 pankaj.gupta@....com, michael.roth@....com, sraithal@....com
Subject: Re: [PATCH v6 2/9] KVM: SEV: Disable SEV on platform init failure

On 2/11/25 7:58 PM, Sean Christopherson wrote:
> On Mon, Feb 03, 2025, Pratik R. Sampat wrote:
>> If the platform initialization sev_platform_init() fails, SEV cannot be
>> set up and a secure VM cannot be spawned. Therefore, in this case,
>> ensure that KVM does not set up, nor advertise support for SEV, SEV-ES,
>> and SEV-SNP.
>>
>> Suggested-by: Nikunj A Dadhania <nikunj@....com>
>> Tested-by: Srikanth Aithal <sraithal@....com>
>> Signed-off-by: Pratik R. Sampat <prsampat@....com>
>> ---
>> v5..v6:
>>
>> * Rename is_sev_platform_init to sev_fw_initialized (Nikunj)
>> * Collected tags from Srikanth.
>> ---
>>  arch/x86/kvm/svm/sev.c       |  2 +-
>>  drivers/crypto/ccp/sev-dev.c | 10 ++++++++++
>>  include/linux/psp-sev.h      |  3 +++
>>  3 files changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
>> index b709c2f0945c..42d1309f8a54 100644
>> --- a/arch/x86/kvm/svm/sev.c
>> +++ b/arch/x86/kvm/svm/sev.c
>> @@ -2957,7 +2957,7 @@ void __init sev_hardware_setup(void)
>>  	bool sev_es_supported = false;
>>  	bool sev_supported = false;
>>  
>> -	if (!sev_enabled || !npt_enabled || !nrips)
>> +	if (!sev_fw_initialized() || !sev_enabled || !npt_enabled || !nrips)
>>  		goto out;
> 
> Me thinks this wasn't tested with KVM_AMD built-in[1].  I'm pretty sure Ashish's
> fix[2] solves all of this?
> 
> [1] https://lore.kernel.org/all/d6d08c6b-9602-4f3d-92c2-8db6d50a1b92@amd.com
> [2] https://lore.kernel.org/all/f78ddb64087df27e7bcb1ae0ab53f55aa0804fab.1739226950.git.ashish.kalra@amd.com

Thanks for pointing this out. I hadn't considered this earlier.

The combination of both of these should solve all of the issues caused
by a failing SEV INIT. I will remove this patch for the next iteration
then.

Thanks!