linux-kernel - Re: [PATCH 2/3] x86/sev: Add defines for GHCB version 2 MSR protocol requests

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Message-ID: <93fe4681-eb0c-d901-9497-336efb4429a6@amd.com>
Date:   Wed, 23 Jun 2021 07:33:09 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>
Cc:     brijesh.singh@....com, x86@...nel.org,
        Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>, hpa@...or.com,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Martin Radev <martin.b.radev@...il.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH 2/3] x86/sev: Add defines for GHCB version 2 MSR protocol
 requests


On 6/23/21 4:32 AM, Borislav Petkov wrote:
> On Wed, Jun 23, 2021 at 08:40:00AM +0200, Joerg Roedel wrote:
>> From: Brijesh Singh <brijesh.singh@....com>
>>
>> Add the necessary defines for supporting the GHCB version 2 protocol.
>> This includes defines for:
>>
>> 	- MSR-based AP hlt request/response
>> 	- Hypervisor Feature request/response
>>
>> This is the bare minimum of requests that need to be supported by a GHCB
>> version 2 implementation. There are more requests in the specification,
>> but those depend on Secure Nested Paging support being available.
>>
>> These defines are shared between SEV host and guest support, so they are
>> submitted as an individual patch without users yet to avoid merge
>> conflicts in the future.
>>
>> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> Co-developed-by: Tom Lendacky <thomas.lendacky@....com>
>> Signed-off-by: Joerg Roedel <jroedel@...e.de>
>> ---
>>  arch/x86/include/asm/sev-common.h | 15 +++++++++++++++
>>  1 file changed, 15 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
>> index 1cc9e7dd8107..9aa2f29b4c97 100644
>> --- a/arch/x86/include/asm/sev-common.h
>> +++ b/arch/x86/include/asm/sev-common.h
>> @@ -47,6 +47,21 @@
>>  		(((unsigned long)reg & GHCB_MSR_CPUID_REG_MASK) << GHCB_MSR_CPUID_REG_POS) | \
>>  		(((unsigned long)fn) << GHCB_MSR_CPUID_FUNC_POS))
>>  
>> +/* AP Reset Hold */
>> +#define GHCB_MSR_AP_RESET_HOLD_REQ		0x006
>> +#define GHCB_MSR_AP_RESET_HOLD_RESP		0x007
>> +#define GHCB_MSR_AP_RESET_HOLD_RESULT_POS	12
>> +#define GHCB_MSR_AP_RESET_HOLD_RESULT_MASK	GENMASK_ULL(51, 0)
>> +
>> +/* GHCB Hypervisor Feature Request/Response */
>> +#define GHCB_MSR_HV_FT_REQ			0x080
>> +#define GHCB_MSR_HV_FT_RESP			0x081
>> +#define GHCB_MSR_HV_FT_POS			12
>> +#define GHCB_MSR_HV_FT_MASK			GENMASK_ULL(51, 0)
>> +
>> +#define GHCB_MSR_HV_FT_RESP_VAL(v)		\
>> +	((unsigned long)((v) >> GHCB_MSR_HV_FT_POS) & GHCB_MSR_HV_FT_MASK)
>> +
> Ok, so I took a critical look at this and it doesn't make sense to have
> a differently named define each time you need the [63:12] slice of
> GHCBData. So you can simply use GHCB_DATA(msr_value) instead, see below.
>
> Complaints?

Looks good to me.