linux-kernel - Re: [PATCH kernel v5 6/6] x86/sev: Do not handle #VC for DR7 read/write

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Message-ID: <52148837-85da-f9f7-ee9a-a7903c0f0d06@amd.com>
Date:   Wed, 24 May 2023 16:36:17 +1000
From:   Alexey Kardashevskiy <aik@....com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
        Tom Lendacky <thomas.lendacky@....com>,
        Pankaj Gupta <pankaj.gupta@....com>,
        Nikunj A Dadhania <nikunj@....com>,
        Santosh Shukla <santosh.shukla@....com>,
        Carlos Bilbao <carlos.bilbao@....com>
Subject: Re: [PATCH kernel v5 6/6] x86/sev: Do not handle #VC for DR7
 read/write



On 23/5/23 09:44, Sean Christopherson wrote:
> On Tue, Apr 11, 2023, Alexey Kardashevskiy wrote:
>> With MSR_AMD64_SEV_DEBUG_SWAP enabled, the guest is not expected to
>> receive a #VC for reads or writes of DR7.
>>
>> Update the SNP_FEATURES_PRESENT mask with MSR_AMD64_SNP_DEBUG_SWAP so
>> an SNP guest doesn't gracefully terminate during SNP feature negotiation
>> if MSR_AMD64_SEV_DEBUG_SWAP is enabled.
>>
>> Since a guest is not expected to receive a #VC on DR7 accesses when
>> MSR_AMD64_SEV_DEBUG_SWAP is enabled, return an error from the #VC
>> handler in this situation.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@....com>
>> Reviewed-by: Carlos Bilbao <carlos.bilbao@....com>
>> Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
>> Reviewed-by: Pankaj Gupta <pankaj.gupta@....com>
>> ---
>> Changes:
>> v4:
>> * rebased on top of SNP feature negotiation
>>
>> v2:
>> * use new bit definition
>> ---
>>   arch/x86/boot/compressed/sev.c | 2 +-
>>   arch/x86/kernel/sev.c          | 6 ++++++
>>   2 files changed, 7 insertions(+), 1 deletion(-)
> 
> Can you post this separately (or bribe Boris to grab it)?  IIUC, this has no
> dependency on the KVM enabling, i.e. can/should go through the tip tree without
> waiting for the KVM patches to be applied.

I definitely can, do you mind adding yours "rb"/"ab"? Thanks!


-- 
Alexey