linux-kernel - [PATCH 04/32] KVM: x86/lapic: Wire DEADLINE MSR update to guest virtual TSC deadline

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Message-ID: <799fefe0c582ac5f9356a9a9a3dbf521b03cf39b.1770116050.git.isaku.yamahata@intel.com>
Date: Tue,  3 Feb 2026 10:16:47 -0800
From: isaku.yamahata@...el.com
To: kvm@...r.kernel.org
Cc: isaku.yamahata@...el.com,
	isaku.yamahata@...il.com,
	Paolo Bonzini <pbonzini@...hat.com>,
	Sean Christopherson <seanjc@...gle.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 04/32] KVM: x86/lapic: Wire DEADLINE MSR update to guest virtual TSC deadline

From: Isaku Yamahata <isaku.yamahata@...el.com>

Wire userpace read/write (KVM_GET_MSRS, KVM_SET_MSRS) of TSCDEADLINE MSR to
the vendor backend to update the VMCS field of GUEST TSCDEADLINE and
GUEST TSCDEADLINE shadow.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/lapic.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index ee15d3bf5ef9..080245f6dac1 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2754,6 +2754,10 @@ u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu)
 	if (!kvm_apic_present(vcpu) || !apic_lvtt_tscdeadline(apic))
 		return 0;
 
+	if (apic->lapic_timer.apic_virt_timer_in_use)
+		apic->lapic_timer.tscdeadline =
+			kvm_x86_call(get_guest_tsc_deadline_virt)(vcpu);
+
 	return apic->lapic_timer.tscdeadline;
 }
 
@@ -2766,6 +2770,8 @@ void kvm_set_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu, u64 data)
 
 	hrtimer_cancel(&apic->lapic_timer.timer);
 	apic->lapic_timer.tscdeadline = data;
+	if (apic->lapic_timer.apic_virt_timer_in_use)
+		kvm_x86_call(set_guest_tsc_deadline_virt)(vcpu, data);
 	start_apic_timer(apic);
 }
 
-- 
2.45.2