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Subject: Re: [PATCH Part1 RFC v2 13/20] x86/sev: Register GHCB memory when
 SEV-SNP is active
To:     Borislav Petkov <bp@alien8.de>
References: <20210430121616.2295-1-brijesh.singh@amd.com>
 <20210430121616.2295-14-brijesh.singh@amd.com> <YKzbfwD6nHL7ChcJ@zn.tnic>
 <b15cd25b-ee69-237d-9044-84fba2cf4bb2@amd.com> <YK0LFk3xMjfirG9E@zn.tnic>
From:   Brijesh Singh <brijesh.singh@amd.com>
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Date:   Tue, 25 May 2021 09:47:24 -0500
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On 5/25/21 9:35 AM, Borislav Petkov wrote:
>> In this particular case, the snp_register_ghcb() is shared between the
>> decompress and main kernel. The variable data->snp_ghcb_registered is
>> not visible in the decompressed path,
> Why is it not visible?

Maybe I should have said, its not applicable in the decompressed path.

The snp_ghcb_register is defined in the per-CPU structure, and used in
the per-CPU #VC handler. We don't have the per-CPU #VC handler in the
decompression code path.

Please see the arch/x86/kernel/sev.c

/* #VC handler runtime per-CPU data */

struct sev_es_runtime_data {

 ...

 ...

 bool snp_ghcb_registered;

}