From: Joerg Roedel <jroedel@xxxxxxx>
The error path in the runtime #VC handler sends a signal to kill the
current task if the exception was raised from user-space. Some parts of
the #VC handler run in NMI mode, because it is critical that it is not
interrupted (except from an NMI) while the GHCB is in use.
But sending signals in NMI-mode is actually broken and triggers lockdep
warnings. On the other side, when the signal is sent, there is no reason
for the handler to still be in NMI-mode, as the GHCB is not used
anymore.
Leave NMI-mode before entering the error path to get rid of the lockdep
warnings.
Fixes: 62441a1fb532 ("x86/sev-es: Correctly track IRQ states in runtime #VC handler")
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
---
arch/x86/kernel/sev.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 4fd997bbf059..9a64030e74c0 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -1343,9 +1343,10 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
return;
}
+ instrumentation_begin();
+
irq_state = irqentry_nmi_enter(regs);
lockdep_assert_irqs_disabled();
- instrumentation_begin();
/*
* This is invoked through an interrupt gate, so IRQs are disabled. The
@@ -1395,13 +1396,19 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
BUG();
}
-out:
- instrumentation_end();
irqentry_nmi_exit(regs, irq_state);
+ instrumentation_end();
return;
fail:
+ /*
+ * Leave NMI mode - the GHCB is not busy anymore and depending on where
+ * the #VC came from this code is about to either kill the task (when in
+ * task context) or kill the machine.
+ */
+ irqentry_nmi_exit(regs, irq_state);
+
if (user_mode(regs)) {
/*
* Do not kill the machine if user-space triggered the
@@ -1423,7 +1430,9 @@ DEFINE_IDTENTRY_VC_SAFE_STACK(exc_vmm_communication)
panic("Returned from Terminate-Request to Hypervisor\n");
}
- goto out;
+ instrumentation_end();
+
+ return;
}
/* This handler runs on the #VC fall-back stack. It can cause further #VC exceptions */
--
2.31.1
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