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Re: [RFC PATCH v2 04/12] i386/sev: initialize SNP context
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From: |
Brijesh Singh |
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Subject: |
Re: [RFC PATCH v2 04/12] i386/sev: initialize SNP context |
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Date: |
Sun, 5 Sep 2021 09:05:07 -0500 |
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User-agent: |
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 |
On 9/5/21 4:19 AM, Dov Murik wrote:
>
> On 27/08/2021 1:26, Michael Roth wrote:
>> From: Brijesh Singh <brijesh.singh@amd.com>
>>
>> When SEV-SNP is enabled, the KVM_SNP_INIT command is used to initialize
>> the platform. The command checks whether SNP is enabled in the KVM, if
>> enabled then it allocates a new ASID from the SNP pool and calls the
>> firmware to initialize the all the resources.
>>
>
> From the KVM code ("[PATCH Part2 v5 24/45] KVM: SVM: Add
> KVM_SEV_SNP_LAUNCH_START command") it seems that KVM_SNP_INIT does *not*
> allocate the ASID; actually this is done in KVM_SEV_SNP_LAUNCH_START.
Actually, the KVM_SNP_INIT does allocate the ASID. If you look at the
driver code then in switch state, the SNP_INIT fallthrough to SEV_INIT
which will call sev_guest_init(). The sev_guest_init() allocates a new
ASID.
https://github.com/AMDESE/linux/blob/bb9ba49cd9b749d5551aae295c091d8757153dd7/arch/x86/kvm/svm/sev.c#L255
The LAUNCH_START simply binds the ASID to a guest.
thanks