linux-kernel - [PATCH] KVM: x86: Remove outdated comments and code in kvm_on_user

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Message-Id: <c10fb477105231e62da28f12c94c5452fa1eff74.1757662000.git.houwenlong.hwl@antgroup.com>
Date: Fri, 12 Sep 2025 15:35:29 +0800
From: Hou Wenlong <houwenlong.hwl@...group.com>
To: kvm@...r.kernel.org
Cc: Sean Christopherson <seanjc@...gle.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	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,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86: Remove outdated comments and code in kvm_on_user_return()

The commit a377ac1cd9d7b ("x86/entry: Move user return notifier out of
loop") moved fire_user_return_notifiers() into the section with
interrupts disabled, so the callback kvm_on_user_return() cannot be
interrupted by kvm_arch_disable_virtualization_cpu() now. Therefore,
remove the outdated comments and local_irq_save()/local_irq_restore()
code in kvm_on_user_return().

Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/x86.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 33fba801b205..10afbacb1851 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -568,18 +568,12 @@ static void kvm_on_user_return(struct user_return_notifier *urn)
 	struct kvm_user_return_msrs *msrs
 		= container_of(urn, struct kvm_user_return_msrs, urn);
 	struct kvm_user_return_msr_values *values;
-	unsigned long flags;

-	/*
-	 * Disabling irqs at this point since the following code could be
-	 * interrupted and executed through kvm_arch_disable_virtualization_cpu()
-	 */
-	local_irq_save(flags);
-	if (msrs->registered) {
-		msrs->registered = false;
-		user_return_notifier_unregister(urn);
-	}
-	local_irq_restore(flags);
+	lockdep_assert_irqs_disabled();
+
+	msrs->registered = false;
+	user_return_notifier_unregister(urn);
+
 	for (slot = 0; slot < kvm_nr_uret_msrs; ++slot) {
 		values = &msrs->values[slot];
 		if (values->host != values->curr) {
--
2.31.1