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Date:   Sat, 29 Jan 2022 11:27:13 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Brijesh Singh <brijesh.singh@amd.com>
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        sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH v8 36/40] x86/sev: Provide support for SNP guest request
 NAEs
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References: <20211210154332.11526-1-brijesh.singh@amd.com>
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On Thu, Jan 27, 2022 at 11:02:13AM -0600, Brijesh Singh wrote:
> I am okay with using SZ_4G but per the spec they don't spell that its 4G
> size. It says bit 32 will should be set on error.

What does the speck call it exactly? Is it "length"? Because that's what
confused me: SNP_GUEST_REQ_INVALID_LEN - that's a length and length you
don't usually specify with a bit position...

> Typically the sev_es_ghcb_hv_handler() is called from #VC handler, which
> provides the context structure. But in this and PSC case, the caller is not
> a #VC handler, so we don't have a context structure. But as you pointed, we
> could allocate context structure on the stack and pass it down so that
> verify_exception_info() does not cause a panic with NULL deference (when HV
> violates the spec and inject exception while handling this NAE).

Yap, exactly.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette