linux-kernel - [PATCH 07/11] virt/coco/sev-guest: Convert the sw_exit_info

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Date:   Thu, 16 Feb 2023 13:45:58 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Dionna Glaze <dionnaglaze@...gle.com>,
        Joerg Roedel <jroedel@...e.de>,
        Michael Roth <michael.roth@....com>,
        Nikunj A Dadhania <nikunj@....com>,
        Peter Gonda <pgonda@...gle.com>,
        Tom Lendacky <Thomas.Lendacky@....com>,
        linux-coco@...ts.linux.dev, x86@...nel.org
Subject: [PATCH 07/11] virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case

From: "Borislav Petkov (AMD)" <bp@...en8.de>

snp_issue_guest_request() checks the value returned by the hypervisor in
sw_exit_info_2 and returns a different error depending on it.

Convert those checks into a switch-case to make it more readable when
more error values are going to be checked in the future.

No functional changes.

Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
---
 arch/x86/kernel/sev.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index ee53cab887fa..d6655fccefc8 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2209,17 +2209,23 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
 	if (ret)
 		goto e_put;
 
-	if (ghcb->save.sw_exit_info_2) {
+	*fw_err = ghcb->save.sw_exit_info_2;
+	switch (*fw_err) {
+	case 0:
+		break;
+
+	case SNP_GUEST_REQ_INVALID_LEN:
 		/* Number of expected pages are returned in RBX */
-		if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST &&
-		    ghcb->save.sw_exit_info_2 == SNP_GUEST_REQ_INVALID_LEN) {
+		if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) {
 			input->data_npages = ghcb_get_rbx(ghcb);
 			ret = -ENOSPC;
-		} else {
-			ret = -EIO;
+			break;
 		}
+		fallthrough;
 
-		*fw_err = ghcb->save.sw_exit_info_2;
+	default:
+		ret = -EIO;
+		break;
 	}
 
 e_put:
-- 
2.35.1