From: Joerg Roedel <jroedel@xxxxxxx>
The sev_es_get_ghcb() is called from several places, but only one of
them checks the return value. The reaction to returning NULL is always
the same: Calling panic() and kill the machine.
Instead of adding checks to all call-places, move the panic() into the
function itself so that it will no longer return NULL.
Fixes: 0786138c78e7 ("x86/sev-es: Add a Runtime #VC Exception Handler")
Cc: stable@xxxxxxxxxxxxxxx # v5.10+
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
arch/x86/kernel/sev.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4fa111becc93..82bced88153b 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -203,8 +203,18 @@ static __always_inline struct ghcb *sev_es_get_ghcb(struct ghcb_state *state)
if (unlikely(data->ghcb_active)) {
/* GHCB is already in use - save its contents */
- if (unlikely(data->backup_ghcb_active))
- return NULL;
+ if (unlikely(data->backup_ghcb_active)) {
+ /*
+ * Backup-GHCB is also already in use. There is no way
+ * to continue here so just kill the machine. To make
+ * panic() work, mark GHCBs inactive so that messages
+ * can be printed out.
+ */
+ data->ghcb_active = false;
+ data->backup_ghcb_active = false;
+
+ panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
+ }
/* Mark backup_ghcb active before writing to it */
data->backup_ghcb_active = true;
@@ -1289,7 +1299,6 @@ static __always_inline bool on_vc_fallback_stack(struct pt_regs *regs)
*/
DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
{
- struct sev_es_runtime_data *data = this_cpu_read(runtime_data);
irqentry_state_t irq_state;
struct ghcb_state state;
struct es_em_ctxt ctxt;
@@ -1315,16 +1324,6 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
*/
ghcb = sev_es_get_ghcb(&state);
- if (!ghcb) {
- /*
- * Mark GHCBs inactive so that panic() is able to print the
- * message.
- */
- data->ghcb_active = false;
- data->backup_ghcb_active = false;
-
- panic("Unable to handle #VC exception! GHCB and Backup GHCB are already in use");
- }
vc_ghcb_invalidate(ghcb);
result = vc_init_em_ctxt(&ctxt, regs, error_code);
--
2.31.1
