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

From: Brijesh Singh <brijesh.singh@amd.com>
To: Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>
Cc: brijesh.singh@amd.com, x86@kernel.org,
	Joerg Roedel <jroedel@suse.de>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	hpa@zytor.com, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 2/3] x86/sev: Add defines for GHCB version 2 MSR protocol requests
Date: Wed, 23 Jun 2021 07:33:09 -0500	[thread overview]
Message-ID: <93fe4681-eb0c-d901-9497-336efb4429a6@amd.com> (raw)
In-Reply-To: <YNL/wpVY1PmGJASW@zn.tnic>

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@amd.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@amd.com>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> Co-developed-by: Tom Lendacky <thomas.lendacky@amd.com>
>> Signed-off-by: Joerg Roedel <jroedel@suse.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.