[PATCH RFC 07/13] x86/irq: Add helpers for checking Intel PID

[Jacob Pan]

Intel posted interrupt descriptor (PID) stores pending interrupts in its
posted interrupt requests (PIR) bitmap.

Add helper functions to check individual vector status and the entire bitmap.

They are used for interrupt migration and runtime demultiplexing posted MSI
vectors.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/posted_intr.h | 31 ++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/x86/include/asm/posted_intr.h b/arch/x86/include/asm/posted_intr.h
index 3af00f5395e4..12a4fa3ff60e 100644
--- a/arch/x86/include/asm/posted_intr.h
+++ b/arch/x86/include/asm/posted_intr.h
@@ -98,9 +98,40 @@ static inline bool pi_test_sn(struct pi_desc *pi_desc)
 }
 
 #ifdef CONFIG_X86_POSTED_MSI
+/*
+ * Not all external vectors are subject to interrupt remapping, e.g. IOMMU's
+ * own interrupts. Here we do not distinguish them since those vector bits in
+ * PIR will always be zero.
+ */
+static inline bool is_pi_pending_this_cpu(unsigned int vector)
+{
+	struct pi_desc *pid;
+
+	if (WARN_ON(vector > NR_VECTORS || vector < FIRST_EXTERNAL_VECTOR))
+		return false;
+
+	pid = this_cpu_ptr(&posted_interrupt_desc);
+
+	return (pid->pir[vector >> 5] & (1 << (vector % 32)));
+}
+
+static inline bool is_pir_pending(struct pi_desc *pid)
+{
+	int i;
+
+	for (i = 0; i < 4; i++) {
+		if (pid->pir_l[i])
+			return true;
+	}
+
+	return false;
+}
+
 extern void intel_posted_msi_init(void);
 
 #else
+static inline bool is_pi_pending_this_cpu(unsigned int vector) {return false; }
+
 static inline void intel_posted_msi_init(void) {};
 
 #endif /* X86_POSTED_MSI */
-- 
2.25.1