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Date:   Wed, 24 May 2023 16:36:17 +1000
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Subject: Re: [PATCH kernel v5 6/6] x86/sev: Do not handle #VC for DR7
 read/write
Content-Language: en-US
To:     Sean Christopherson <seanjc@google.com>
Cc:     kvm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Pankaj Gupta <pankaj.gupta@amd.com>,
        Nikunj A Dadhania <nikunj@amd.com>,
        Santosh Shukla <santosh.shukla@amd.com>,
        Carlos Bilbao <carlos.bilbao@amd.com>
References: <20230411125718.2297768-1-aik@amd.com>
 <20230411125718.2297768-7-aik@amd.com> <ZGv+Y60qvbjeTY57@google.com>
From:   Alexey Kardashevskiy <aik@amd.com>
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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@amd.com>
>> Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
>> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
>> Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.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