linux-kernel - [PATCH 07/16] KVM: TDX: Wait lapic expire when timer IRQ was injected

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Message-ID: <20241209010734.3543481-8-binbin.wu@linux.intel.com>
Date: Mon,  9 Dec 2024 09:07:21 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: pbonzini@...hat.com,
	seanjc@...gle.com,
	kvm@...r.kernel.org
Cc: rick.p.edgecombe@...el.com,
	kai.huang@...el.com,
	adrian.hunter@...el.com,
	reinette.chatre@...el.com,
	xiaoyao.li@...el.com,
	tony.lindgren@...ux.intel.com,
	isaku.yamahata@...el.com,
	yan.y.zhao@...el.com,
	chao.gao@...el.com,
	linux-kernel@...r.kernel.org,
	binbin.wu@...ux.intel.com
Subject: [PATCH 07/16] KVM: TDX: Wait lapic expire when timer IRQ was injected

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

Call kvm_wait_lapic_expire() when POSTED_INTR_ON is set and the vector
for LVTT is set in PIR before TD entry.

KVM always assumes a timer IRQ was injected if APIC state is protected.
For TDX guest, APIC state is protected and KVM injects timer IRQ via posted
interrupt.  To avoid unnecessary wait calls, only call kvm_wait_lapic_expire()
when a timer IRQ was injected, i.e., POSTED_INTR_ON is set and the vector for
LVTT is set in PIR.

Add a helper to test PIR.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
Co-developed-by: Binbin Wu <binbin.wu@...ux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@...ux.intel.com>
---
TDX interrupts breakout:
- Split out from patch "KVM: TDX: Implement interrupt injection". (Chao)
- Check PIR against LVTT vector.
---
 arch/x86/include/asm/posted_intr.h | 5 +++++
 arch/x86/kvm/vmx/tdx.c             | 7 ++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/posted_intr.h b/arch/x86/include/asm/posted_intr.h
index de788b400fba..bb107ebbe713 100644
--- a/arch/x86/include/asm/posted_intr.h
+++ b/arch/x86/include/asm/posted_intr.h
@@ -81,6 +81,11 @@ static inline bool pi_test_sn(struct pi_desc *pi_desc)
 	return test_bit(POSTED_INTR_SN, (unsigned long *)&pi_desc->control);
 }
 
+static inline bool pi_test_pir(int vector, struct pi_desc *pi_desc)
+{
+	return test_bit(vector, (unsigned long *)pi_desc->pir);
+}
+
 /* Non-atomic helpers */
 static inline void __pi_set_sn(struct pi_desc *pi_desc)
 {
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 0896e0e825ed..dcbe25695d85 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -974,9 +974,14 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
 
 	trace_kvm_entry(vcpu, force_immediate_exit);
 
-	if (pi_test_on(&tdx->pi_desc))
+	if (pi_test_on(&tdx->pi_desc)) {
 		apic->send_IPI_self(POSTED_INTR_VECTOR);
 
+		if(pi_test_pir(kvm_lapic_get_reg(vcpu->arch.apic, APIC_LVTT) &
+			       APIC_VECTOR_MASK, &tdx->pi_desc))
+			kvm_wait_lapic_expire(vcpu);
+	}
+
 	tdx_vcpu_enter_exit(vcpu);
 
 	if (tdx->host_debugctlmsr & ~TDX_DEBUGCTL_PRESERVED)
-- 
2.46.0