[PATCH -v2 07/11] virt/coco/sev-guest: Convert the sw_exit_info_2 checking to a switch-case

From: Borislav Petkov
Date: Tue Feb 21 2023 - 06:35:19 EST


From: "Borislav Petkov (AMD)" <bp@xxxxxxxxx>

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@xxxxxxxxx>
---
arch/x86/kernel/sev.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 6a3e1425ba17..d67884fb38c1 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2210,15 +2210,21 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned
goto e_put;

*fw_err = ghcb->save.sw_exit_info_2;
- if (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;
+ default:
+ ret = -EIO;
+ break;
}

e_put:
--
2.35.1