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

Borislav Petkov
2021-06-23T09:33:03Z

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?

---
From: Brijesh Singh <brijesh.singh@amd.com>
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@8bytes.org too.
Simplify the brewing macro maze into readability. ]

Co-developed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/YNLXQIZ5e1wjkshG@8bytes.org
---
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.