From bf1ff8c98f2e4f585096c156b9d5349f05e9aaed Mon Sep 17 00:00:00 2001
From: Sainath Grandhi <sainath.grandhi@intel.com>
Date: Wed, 29 Apr 2020 20:37:25 -0700
Subject: [PATCH] hv: Offload syncing PIR to vIRR to processor hardware

ACRN syncs PIR to vIRR in the software in cases the Posted
Interrupt notification happens while the pCPU is in root mode.

Sync can be achieved by processor hardware by sending a
posted interrupt notiification vector.

This patch sends a self-IPI, if there are interrupts pending in PIR,
which is serviced by the logical processor at the next
VMEnter

Tracked-On: #4777
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
---
 hypervisor/arch/x86/guest/vlapic.c | 82 ++++++------------------------
 1 file changed, 15 insertions(+), 67 deletions(-)

diff --git a/hypervisor/arch/x86/guest/vlapic.c b/hypervisor/arch/x86/guest/vlapic.c
index 7b12e5b4f..5a47a9110 100644
--- a/hypervisor/arch/x86/guest/vlapic.c
+++ b/hypervisor/arch/x86/guest/vlapic.c
@@ -2228,75 +2228,21 @@ static void apicv_basic_inject_intr(struct acrn_vlapic *vlapic,
 }
 
 /*
- * Transfer the pending interrupts in the PIR descriptor to the IRR
- * in the virtual APIC page.
- * @pre get_pi_desc(vlapic2vcpu(vlapic)) != NULL
+ * @brief Send a Posted Interrupt to itself.
+ *
+ * Interrupts are disabled on pCPU at this point of time.
+ * Upon the next VMEnter the self-IPI is serviced by the logical processor.
+ * Since the IPI vector is Posted Interrupt vector, logical processor syncs
+ * PIR to vIRR and updates RVI.
+ *
+ * @pre get_pi_desc(vlapic->vcpu) != NULL
  */
-static void vlapic_apicv_inject_pir(struct acrn_vlapic *vlapic)
-{
-	struct pi_desc *pid;
-	struct lapic_regs *lapic;
-	uint64_t val, pirval;
-	uint16_t rvi, pirbase = 0U, i;
-	uint16_t intr_status_old, intr_status_new;
-	struct lapic_reg *irr = NULL;
-
-	pid = get_pi_desc(vlapic2vcpu(vlapic));
-	if (bitmap_test_and_clear_lock(POSTED_INTR_ON, &pid->control.value)) {
-		pirval = 0UL;
-		lapic = &(vlapic->apic_page);
-		irr = &lapic->irr[0];
-
-		for (i = 0U; i < 4U; i++) {
-			val = atomic_readandclear64(&pid->pir[i]);
-			if (val != 0UL) {
-				irr[i * 2U].v |= (uint32_t)val;
-				irr[(i * 2U) + 1U].v |= (uint32_t)(val >> 32U);
-
-				pirbase = 64U * i;
-				pirval = val;
-			}
-		}
-
-		/*
-		 * Update RVI so the processor can evaluate pending virtual
-		 * interrupts on VM-entry.
-		 *
-		 * It is possible for pirval to be 0 here, even though the
-		 * pending bit has been set. The scenario is:
-		 * CPU-Y is sending a posted interrupt to CPU-X, which
-		 * is running a guest and processing posted interrupts in h/w.
-		 * CPU-X will eventually exit and the state seen in s/w is
-		 * the pending bit set, but no PIR bits set.
-		 *
-		 *      CPU-X                      CPU-Y
-		 *   (vm running)                (host running)
-		 *   rx posted interrupt
-		 *   CLEAR pending bit
-		 *				 SET PIR bit
-		 *   READ/CLEAR PIR bits
-		 *				 SET pending bit
-		 *   (vm exit)
-		 *   pending bit set, PIR 0
-		 */
-		if (pirval != 0UL) {
-			rvi = pirbase + fls64(pirval);
-
-			intr_status_old = 0xFFFFU &
-					exec_vmread16(VMX_GUEST_INTR_STATUS);
-
-			intr_status_new = (intr_status_old & 0xFF00U) | rvi;
-			if (intr_status_new > intr_status_old) {
-				exec_vmwrite16(VMX_GUEST_INTR_STATUS,
-						intr_status_new);
-			}
-		}
-	}
-}
 
 static void apicv_advanced_inject_intr(struct acrn_vlapic *vlapic,
 		__unused bool guest_irq_enabled, __unused bool injected)
 {
+	struct acrn_vcpu *vcpu = vlapic2vcpu(vlapic);
+	struct pi_desc *pid = get_pi_desc(vcpu);
 	/*
 	 * From SDM Vol3 26.3.2.5:
 	 * Once the virtual interrupt is recognized, it will be delivered
@@ -2307,10 +2253,12 @@ static void apicv_advanced_inject_intr(struct acrn_vlapic *vlapic,
 	 * evaluation/delivery of apicv virtual interrupts in one time
 	 * vm-entry.
 	 *
-	 * Here to sync the pending interrupts to irr and update rvi if
-	 * needed. And then try to handle vmcs event injection.
+	 * Here to sync the pending interrupts to irr and update rvi
+	 * self-IPI with Posted Interrupt Notification Vector is sent.
 	 */
-	vlapic_apicv_inject_pir(vlapic);
+	if (bitmap_test(POSTED_INTR_ON, &(pid->control.value))) {
+		apicv_trigger_pi_anv(pcpuid_from_vcpu(vcpu), (uint32_t)(vcpu->arch.pid.control.bits.nv));
+	}
 }
 
 void vlapic_inject_intr(struct acrn_vlapic *vlapic, bool guest_irq_enabled, bool injected)