linux-kernel - [PATCH v2 1/7] KVM: x86: Move kvm

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Message-ID: <20251206011054.494190-2-seanjc@google.com>
Date: Fri,  5 Dec 2025 17:10:48 -0800
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, 
	Kiryl Shutsemau <kas@...nel.org>, Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	kvm@...r.kernel.org, Chao Gao <chao.gao@...el.com>, 
	Dan Williams <dan.j.williams@...el.com>
Subject: [PATCH v2 1/7] KVM: x86: Move kvm_rebooting to x86

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@...gle.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