linux-kernel - [PATCH v9 06/24] virt: sev-guest: Simplify VMPCK and sequence number assignments

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Message-ID: <20240531043038.3370793-7-nikunj@amd.com>
Date: Fri, 31 May 2024 10:00:20 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>, <bp@...en8.de>,
	<x86@...nel.org>, <kvm@...r.kernel.org>
CC: <mingo@...hat.com>, <tglx@...utronix.de>, <dave.hansen@...ux.intel.com>,
	<pgonda@...gle.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
	<nikunj@....com>
Subject: [PATCH v9 06/24] virt: sev-guest: Simplify VMPCK and sequence number assignments

Preparatory patch to remove direct usage of VMPCK and message sequence
number in the SEV guest driver. Use arrays for the VM platform
communication key and message sequence number to simplify the function and
usage.

Signed-off-by: Nikunj A Dadhania <nikunj@....com>
---
 arch/x86/include/asm/sev.h              | 12 ++++-------
 drivers/virt/coco/sev-guest/sev-guest.c | 27 ++++---------------------
 2 files changed, 8 insertions(+), 31 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index dbf17e66d52a..d06b08f7043c 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -118,6 +118,8 @@ struct sev_guest_platform_data {
 	u64 secrets_gpa;
 };
 
+#define VMPCK_MAX_NUM		4
+
 /*
  * The secrets page contains 96-bytes of reserved field that can be used by
  * the guest OS. The guest OS uses the area to save the message sequence
@@ -126,10 +128,7 @@ struct sev_guest_platform_data {
  * See the GHCB spec section Secret page layout for the format for this area.
  */
 struct secrets_os_area {
-	u32 msg_seqno_0;
-	u32 msg_seqno_1;
-	u32 msg_seqno_2;
-	u32 msg_seqno_3;
+	u32 msg_seqno[VMPCK_MAX_NUM];
 	u64 ap_jump_table_pa;
 	u8 rsvd[40];
 	u8 guest_usage[32];
@@ -145,10 +144,7 @@ struct snp_secrets_page {
 	u32 fms;
 	u32 rsvd2;
 	u8 gosvw[16];
-	u8 vmpck0[VMPCK_KEY_LEN];
-	u8 vmpck1[VMPCK_KEY_LEN];
-	u8 vmpck2[VMPCK_KEY_LEN];
-	u8 vmpck3[VMPCK_KEY_LEN];
+	u8 vmpck[VMPCK_MAX_NUM][VMPCK_KEY_LEN];
 	struct secrets_os_area os_area;
 	u8 rsvd3[3840];
 } __packed;
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 5c0cbdad9fa2..a3c0b22d2e14 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -668,30 +668,11 @@ static const struct file_operations snp_guest_fops = {
 
 static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno)
 {
-	u8 *key = NULL;
-
-	switch (id) {
-	case 0:
-		*seqno = &secrets->os_area.msg_seqno_0;
-		key = secrets->vmpck0;
-		break;
-	case 1:
-		*seqno = &secrets->os_area.msg_seqno_1;
-		key = secrets->vmpck1;
-		break;
-	case 2:
-		*seqno = &secrets->os_area.msg_seqno_2;
-		key = secrets->vmpck2;
-		break;
-	case 3:
-		*seqno = &secrets->os_area.msg_seqno_3;
-		key = secrets->vmpck3;
-		break;
-	default:
-		break;
-	}
+	if ((id + 1) > VMPCK_MAX_NUM)
+		return NULL;
 
-	return key;
+	*seqno = &secrets->os_area.msg_seqno[id];
+	return secrets->vmpck[id];
 }
 
 struct snp_msg_report_resp_hdr {
-- 
2.34.1