linux-kernel - [PATCH v3 08/18] x86/reboot: Expose VMCS crash hooks if and only if KVM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20230512235026.808058-9-seanjc@google.com>
Date:   Fri, 12 May 2023 16:50:16 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>
Subject: [PATCH v3 08/18] x86/reboot: Expose VMCS crash hooks if and only if
 KVM_{INTEL,AMD} is enabled

Expose the crash/reboot hooks used by KVM to disable virtualization in
hardware and unblock INIT only if there's a potential in-tree user,
i.e. either KVM_INTEL or KVM_AMD is enabled.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/reboot.h | 4 ++++
 arch/x86/kernel/reboot.c      | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
index d9a38d379d18..9cf0b21bf495 100644
--- a/arch/x86/include/asm/reboot.h
+++ b/arch/x86/include/asm/reboot.h
@@ -25,10 +25,14 @@ void __noreturn machine_real_restart(unsigned int type);
 #define MRR_BIOS	0
 #define MRR_APM		1
 
+#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD)
 typedef void (cpu_emergency_virt_cb)(void);
 void cpu_emergency_register_virt_callback(cpu_emergency_virt_cb *callback);
 void cpu_emergency_unregister_virt_callback(cpu_emergency_virt_cb *callback);
 void cpu_emergency_disable_virtualization(void);
+#else
+static inline void cpu_emergency_disable_virtualization(void) {}
+#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */
 
 typedef void (*nmi_shootdown_cb)(int, struct pt_regs*);
 void nmi_panic_self_stop(struct pt_regs *regs);
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 493d66e59a4f..6818d8de85a1 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -529,6 +529,7 @@ static inline void kb_wait(void)
 
 static inline void nmi_shootdown_cpus_on_restart(void);
 
+#if IS_ENABLED(CONFIG_KVM_INTEL) || IS_ENABLED(CONFIG_KVM_AMD)
 /* RCU-protected callback to disable virtualization prior to reboot. */
 static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
 
@@ -596,7 +597,9 @@ static void emergency_reboot_disable_virtualization(void)
 		nmi_shootdown_cpus_on_restart();
 	}
 }
-
+#else
+static void emergency_reboot_disable_virtualization(void) { }
+#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */
 
 void __attribute__((weak)) mach_reboot_fixups(void)
 {
-- 
2.40.1.606.ga4b1b128d6-goog