linux-kernel - [PATCH 04/16] x86/reboot: Assert that IRQs are disabled when turning off virtualization

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Message-ID: <20221201232655.290720-5-seanjc@google.com>
Date:   Thu,  1 Dec 2022 23:26:43 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Andrew Cooper <Andrew.Cooper3@...rix.com>
Subject: [PATCH 04/16] x86/reboot: Assert that IRQs are disabled when turning
 off virtualization

Assert that IRQs are disabled when turning off virtualization in an
emergency.  KVM enables hardware via on_each_cpu(), i.e. could re-enable
hardware if a pending IPI were delivered after disabling virtualization.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kernel/reboot.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 78182b2969db..40ea16ecb3b8 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -838,6 +838,8 @@ int crashing_cpu = -1;
  */
 void cpu_emergency_disable_virtualization(void)
 {
+	lockdep_assert_irqs_disabled();
+
 #if IS_ENABLED(CONFIG_KVM_INTEL)
 	cpu_crash_vmclear_loaded_vmcss();
 #endif
-- 
2.39.0.rc0.267.gcb52ba06e7-goog