[PATCH v2 1/7] KVM: x86: Move kvm_rebooting to x86

Sean Christopherson
2025-12-06T01:11:09Z

Move kvm_rebooting, which is only read by x86, to KVM x86 so that it can
be moved again to core x86 code. Add a "shutdown" arch hook to facilate
setting the flag in KVM x86.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/x86.c | 13 +++++++++++++
arch/x86/kvm/x86.h | 1 +
include/linux/kvm_host.h | 2 +-
virt/kvm/kvm_main.c | 14 +++++++-------
4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0c6d899d53dd..80cb882f19e2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -694,6 +694,9 @@ static void drop_user_return_notifiers(void)
kvm_on_user_return(&msrs->urn);
}

+__visible bool kvm_rebooting;
+EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_rebooting);
+
/*
* Handle a fault on a hardware virtualization (VMX or SVM) instruction.
*
@@ -13100,6 +13103,16 @@ int kvm_arch_enable_virtualization_cpu(void)
return 0;
}

+void kvm_arch_shutdown(void)
+{
+ /*
+ * Set kvm_rebooting to indicate that KVM has asynchronously disabled
+ * hardware virtualization, i.e. that relevant errors and exceptions
+ * aren't entirely unexpected.
+ */
+ kvm_rebooting = true;
+}
+
void kvm_arch_disable_virtualization_cpu(void)
{
kvm_x86_call(disable_virtualization_cpu)();
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index fdab0ad49098..40993348a967 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -54,6 +54,7 @@ struct kvm_host_values {
u64 arch_capabilities;
};

+extern bool kvm_rebooting;
void kvm_spurious_fault(void);

#define SIZE_OF_MEMSLOTS_HASHTABLE \
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d93f75b05ae2..a453fe6ce05a 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1621,6 +1621,7 @@ static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
#endif

#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
+void kvm_arch_shutdown(void);
/*
* kvm_arch_{enable,disable}_virtualization() are called on one CPU, under
* kvm_usage_lock, immediately after/before 0=>1 and 1=>0 transitions of
@@ -2302,7 +2303,6 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu)

#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
extern bool enable_virt_at_load;
-extern bool kvm_rebooting;
#endif

extern unsigned int halt_poll_ns;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f1f6a71b2b5f..3278ee9381bd 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5586,13 +5586,15 @@ bool enable_virt_at_load = true;
module_param(enable_virt_at_load, bool, 0444);
EXPORT_SYMBOL_FOR_KVM_INTERNAL(enable_virt_at_load);

-__visible bool kvm_rebooting;
-EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_rebooting);
-
static DEFINE_PER_CPU(bool, virtualization_enabled);
static DEFINE_MUTEX(kvm_usage_lock);
static int kvm_usage_count;

+__weak void kvm_arch_shutdown(void)
+{
+
+}
+
__weak void kvm_arch_enable_virtualization(void)
{

@@ -5646,10 +5648,9 @@ static int kvm_offline_cpu(unsigned int cpu)

static void kvm_shutdown(void)
{
+ kvm_arch_shutdown();
+
/*
- * Disable hardware virtualization and set kvm_rebooting to indicate
- * that KVM has asynchronously disabled hardware virtualization, i.e.
- * that relevant errors and exceptions aren't entirely unexpected.
* Some flavors of hardware virtualization need to be disabled before
* transferring control to firmware (to perform shutdown/reboot), e.g.
* on x86, virtualization can block INIT interrupts, which are used by
@@ -5658,7 +5659,6 @@ static void kvm_shutdown(void)
* 100% comprehensive.
*/
pr_info("kvm: exiting hardware virtualization\n");
- kvm_rebooting = true;
on_each_cpu(kvm_disable_virtualization_cpu, NULL, 1);
}

--
2.52.0.223.gf5cc29aaa4-goog