KVM uses emergency virt call back to shutdown virtualization extension
during crash, so the crash kernel can work correctly.
So far the virt callback is only supported if KVM_INTEL or KVM_AMD is
enabled. TDX guest has similar needs.
Add a config option to gate virt emergency callback support.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/reboot.h | 4 ++--
arch/x86/kernel/reboot.c | 4 ++--
arch/x86/kvm/Kconfig | 5 +++++
3 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/reboot.h b/arch/x86/include/asm/reboot.h
index 6536873f8fc0..f72bdd4abbe8 100644
--- a/arch/x86/include/asm/reboot.h
+++ b/arch/x86/include/asm/reboot.h
@@ -25,14 +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)
+#ifdef CONFIG_EMERGENCY_VIRT_CALLBACK
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 */
+#endif /* CONFIG_EMERGENCY_VIRT_CALLBACK */
typedef void (*nmi_shootdown_cb)(int, struct pt_regs*);
void nmi_shootdown_cpus(nmi_shootdown_cb callback);
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 830425e6d38e..6a781f2f11c8 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -529,7 +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)
+#ifdef CONFIG_EMERGENCY_VIRT_CALLBACK
/* RCU-protected callback to disable virtualization prior to reboot. */
static cpu_emergency_virt_cb __rcu *cpu_emergency_virt_callback;
@@ -599,7 +599,7 @@ static void emergency_reboot_disable_virtualization(void)
}
#else
static void emergency_reboot_disable_virtualization(void) { }
-#endif /* CONFIG_KVM_INTEL || CONFIG_KVM_AMD */
+#endif /* CONFIG_EMERGENCY_VIRT_CALLBACK */
void __attribute__((weak)) mach_reboot_fixups(void)
{
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index ed90f148140d..7df3f0c45cfe 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -80,6 +80,7 @@ config KVM_WERROR
config KVM_INTEL
tristate "KVM for Intel (and compatible) processors support"
depends on KVM && IA32_FEAT_CTL
+ select EMERGENCY_VIRT_CALLBACK
help
Provides support for KVM on processors equipped with Intel's VT
extensions, a.k.a. Virtual Machine Extensions (VMX).
@@ -102,6 +103,7 @@ config X86_SGX_KVM
config KVM_AMD
tristate "KVM for AMD processors support"
depends on KVM && (CPU_SUP_AMD || CPU_SUP_HYGON)
+ select EMERGENCY_VIRT_CALLBACK
help
Provides support for KVM on AMD processors equipped with the AMD-V
(SVM) extensions.
@@ -155,3 +157,6 @@ config KVM_EXTERNAL_WRITE_TRACKING
bool
endif # VIRTUALIZATION
+
+config EMERGENCY_VIRT_CALLBACK
+ bool
--
2.41.0
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