[PATCH v2 06/13] x86/irq: Set up per host CPU posted interrupt descriptors

[Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>]

To support posted MSIs, create a posted interrupt descriptor (PID) for each
host CPU. Later on, when setting up IRQ CPU affinity, IOMMU's interrupt
remapping table entry (IRTE) will point to the physical address of the
matching CPU's PID.

Each PID is initialized with the owner CPU's physical APICID as the
destination.

Originally-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>

---
v2: Fix xAPIC destination ID assignment, Oliver Sang reported failture on
system with x2apic optout BIOS option.
---
 arch/x86/include/asm/hardirq.h     |  3 +++
 arch/x86/include/asm/posted_intr.h |  7 +++++++
 arch/x86/kernel/cpu/common.c       |  3 +++
 arch/x86/kernel/irq.c              | 23 +++++++++++++++++++++++
 4 files changed, 36 insertions(+)

diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
index fbc7722b87d1..01ea52859462 100644
--- a/arch/x86/include/asm/hardirq.h
+++ b/arch/x86/include/asm/hardirq.h
@@ -48,6 +48,9 @@ typedef struct {
 
 DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
 
+#ifdef CONFIG_X86_POSTED_MSI
+DECLARE_PER_CPU_ALIGNED(struct pi_desc, posted_interrupt_desc);
+#endif
 #define __ARCH_IRQ_STAT
 
 #define inc_irq_stat(member)	this_cpu_inc(irq_stat.member)
diff --git a/arch/x86/include/asm/posted_intr.h b/arch/x86/include/asm/posted_intr.h
index c682c41d4e44..4e5eea2d20e0 100644
--- a/arch/x86/include/asm/posted_intr.h
+++ b/arch/x86/include/asm/posted_intr.h
@@ -80,4 +80,11 @@ static inline bool pi_test_sn(struct pi_desc *pi_desc)
 	return test_bit(POSTED_INTR_SN, (unsigned long *)&pi_desc->control);
 }
 
+#ifdef CONFIG_X86_POSTED_MSI
+extern void intel_posted_msi_init(void);
+
+#else
+static inline void intel_posted_msi_init(void) {};
+
+#endif /* X86_POSTED_MSI */
 #endif /* _X86_POSTED_INTR_H */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 5c1e6d6be267..1a5fb657e1b6 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -68,6 +68,7 @@
 #include <asm/traps.h>
 #include <asm/sev.h>
 #include <asm/tdx.h>
+#include <asm/posted_intr.h>
 
 #include "cpu.h"
 
@@ -2219,6 +2220,8 @@ void cpu_init(void)
 		barrier();
 
 		x2apic_setup();
+
+		intel_posted_msi_init();
 	}
 
 	mmgrab(&init_mm);
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c
index 35fde0107901..f39f6147104c 100644
--- a/arch/x86/kernel/irq.c
+++ b/arch/x86/kernel/irq.c
@@ -22,6 +22,8 @@
 #include <asm/desc.h>
 #include <asm/traps.h>
 #include <asm/thermal.h>
+#include <asm/posted_intr.h>
+#include <asm/irq_remapping.h>
 
 #define CREATE_TRACE_POINTS
 #include <asm/trace/irq_vectors.h>
@@ -334,6 +336,27 @@ DEFINE_IDTENTRY_SYSVEC_SIMPLE(sysvec_kvm_posted_intr_nested_ipi)
 }
 #endif
 
+#ifdef CONFIG_X86_POSTED_MSI
+
+/* Posted Interrupt Descriptors for coalesced MSIs to be posted */
+DEFINE_PER_CPU_ALIGNED(struct pi_desc, posted_interrupt_desc);
+
+void intel_posted_msi_init(void)
+{
+	u32 destination;
+	u32 apic_id;
+
+	this_cpu_write(posted_interrupt_desc.nv, POSTED_MSI_NOTIFICATION_VECTOR);
+
+	/*
+	 * APIC destination ID is stored in bit 8:15 while in XAPIC mode.
+	 * VT-d spec. CH 9.11
+	 */
+	apic_id = this_cpu_read(x86_cpu_to_apicid);
+	destination = x2apic_enabled() ? apic_id : apic_id << 8;
+	this_cpu_write(posted_interrupt_desc.ndst, destination);
+}
+#endif /* X86_POSTED_MSI */
 
 #ifdef CONFIG_HOTPLUG_CPU
 /* A cpu has been removed from cpu_online_mask.  Reset irq affinities. */
-- 
2.25.1