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

[Borislav Petkov]

On Wed, Jun 23, 2021 at 08:40:00AM +0200, Joerg Roedel wrote:
> From: Brijesh Singh <brijesh.singh@xxxxxxx>
> 
> 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@xxxxxxx>
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Co-developed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
> ---
>  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?

---
From: Brijesh Singh <brijesh.singh@xxxxxxx>
Date: Wed, 23 Jun 2021 08:40:00 +0200
Subject: [PATCH] x86/sev: Add defines for GHCB version 2 MSR protocol requests

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.

  [ bp: Fold in https://lkml.kernel.org/r/20210622144825.27588-2-joro@xxxxxxxxxx too.
        Simplify the brewing macro maze into readability. ]

Co-developed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lkml.kernel.org/r/YNLXQIZ5e1wjkshG@xxxxxxxxxx
---
 arch/x86/include/asm/sev-common.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 629c3df243f0..2cef6c5a52c2 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -9,8 +9,13 @@
 #define __ASM_X86_SEV_COMMON_H
 
 #define GHCB_MSR_INFO_POS		0
-#define GHCB_MSR_INFO_MASK		(BIT_ULL(12) - 1)
+#define GHCB_DATA_LOW			12
+#define GHCB_MSR_INFO_MASK		(BIT_ULL(GHCB_DATA_LOW) - 1)
 
+#define GHCB_DATA(v)			\
+	(((unsigned long)(v) & ~GHCB_MSR_INFO_MASK) >> GHCB_DATA_LOW)
+
+/* SEV Information Request/Response */
 #define GHCB_MSR_SEV_INFO_RESP		0x001
 #define GHCB_MSR_SEV_INFO_REQ		0x002
 #define GHCB_MSR_VER_MAX_POS		48
@@ -28,6 +33,7 @@
 #define GHCB_MSR_PROTO_MAX(v)		(((v) >> GHCB_MSR_VER_MAX_POS) & GHCB_MSR_VER_MAX_MASK)
 #define GHCB_MSR_PROTO_MIN(v)		(((v) >> GHCB_MSR_VER_MIN_POS) & GHCB_MSR_VER_MIN_MASK)
 
+/* CPUID Request/Response */
 #define GHCB_MSR_CPUID_REQ		0x004
 #define GHCB_MSR_CPUID_RESP		0x005
 #define GHCB_MSR_CPUID_FUNC_POS		32
@@ -45,6 +51,14 @@
 		(((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
+
+/* GHCB Hypervisor Feature Request/Response */
+#define GHCB_MSR_HV_FT_REQ			0x080
+#define GHCB_MSR_HV_FT_RESP			0x081
+
 #define GHCB_MSR_TERM_REQ		0x100
 #define GHCB_MSR_TERM_REASON_SET_POS	12
 #define GHCB_MSR_TERM_REASON_SET_MASK	0xf
-- 
2.29.2

-- 
Regards/Gruss,
    Boris.

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