kvm: x86: add support for KVM_CAP_SPLIT_IRQCHIP

This patch adds support for split IRQ chip mode. When
KVM_CAP_SPLIT_IRQCHIP is enabled:

    1.) The PIC, PIT, and IOAPIC are implemented in userspace while
    the LAPIC is implemented by KVM.

    2.) The software IOAPIC delivers interrupts to the KVM LAPIC via
    kvm_set_irq. Interrupt delivery is configured via the MSI routing
    table, for which routes are reserved in target-i386/kvm.c then
    configured in hw/intc/ioapic.c

    3.) KVM delivers IOAPIC EOIs via a new exit KVM_EXIT_IOAPIC_EOI,
    which is handled in target-i386/kvm.c and relayed to the software
    IOAPIC via ioapic_eoi_broadcast.

Signed-off-by: Matt Gingell <gingell@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 66 insertions, 2 deletions

diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index de2dd4ba8e..e4bfaeade2 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -25,6 +25,8 @@
 #include "hw/i386/pc.h"
 #include "hw/i386/ioapic.h"
 #include "hw/i386/ioapic_internal.h"
+#include "include/hw/pci/msi.h"
+#include "sysemu/kvm.h"
 
 //#define DEBUG_IOAPIC
 
@@ -35,6 +37,10 @@
 #define DPRINTF(fmt, ...)
 #endif
 
+#define APIC_DELIVERY_MODE_SHIFT 8
+#define APIC_POLARITY_SHIFT 14
+#define APIC_TRIG_MODE_SHIFT 15
+
 static IOAPICCommonState *ioapics[MAX_IOAPICS];
 
 /* global variable from ioapic_common.c */
@@ -54,6 +60,8 @@ static void ioapic_service(IOAPICCommonState *s)
     for (i = 0; i < IOAPIC_NUM_PINS; i++) {
         mask = 1 << i;
         if (s->irr & mask) {
+            int coalesce = 0;
+
             entry = s->ioredtbl[i];
             if (!(entry & IOAPIC_LVT_MASKED)) {
                 trig_mode = ((entry >> IOAPIC_LVT_TRIGGER_MODE_SHIFT) & 1);
@@ -64,6 +72,7 @@ static void ioapic_service(IOAPICCommonState *s)
                 if (trig_mode == IOAPIC_TRIGGER_EDGE) {
                     s->irr &= ~mask;
                 } else {
+                    coalesce = s->ioredtbl[i] & IOAPIC_LVT_REMOTE_IRR;
                     s->ioredtbl[i] |= IOAPIC_LVT_REMOTE_IRR;
                 }
                 if (delivery_mode == IOAPIC_DM_EXTINT) {
@@ -71,8 +80,23 @@ static void ioapic_service(IOAPICCommonState *s)
                 } else {
                     vector = entry & IOAPIC_VECTOR_MASK;
                 }
-                apic_deliver_irq(dest, dest_mode, delivery_mode,
-                                 vector, trig_mode);
+#ifdef CONFIG_KVM
+                if (kvm_irqchip_is_split()) {
+                    if (trig_mode == IOAPIC_TRIGGER_EDGE) {
+                        kvm_set_irq(kvm_state, i, 1);
+                        kvm_set_irq(kvm_state, i, 0);
+                    } else {
+                        if (!coalesce) {
+                            kvm_set_irq(kvm_state, i, 1);
+                        }
+                    }
+                    continue;
+                }
+#else
+                (void)coalesce;
+#endif
+                apic_deliver_irq(dest, dest_mode, delivery_mode, vector,
+                                 trig_mode);
             }
         }
     }
@@ -116,6 +140,44 @@ static void ioapic_set_irq(void *opaque, int vector, int level)
     }
 }
 
+static void ioapic_update_kvm_routes(IOAPICCommonState *s)
+{
+#ifdef CONFIG_KVM
+    int i;
+
+    if (kvm_irqchip_is_split()) {
+        for (i = 0; i < IOAPIC_NUM_PINS; i++) {
+            uint64_t entry = s->ioredtbl[i];
+            uint8_t trig_mode;
+            uint8_t delivery_mode;
+            uint8_t dest;
+            uint8_t dest_mode;
+            uint64_t pin_polarity;
+            MSIMessage msg;
+
+            trig_mode = ((entry >> IOAPIC_LVT_TRIGGER_MODE_SHIFT) & 1);
+            dest = entry >> IOAPIC_LVT_DEST_SHIFT;
+            dest_mode = (entry >> IOAPIC_LVT_DEST_MODE_SHIFT) & 1;
+            pin_polarity = (entry >> IOAPIC_LVT_TRIGGER_MODE_SHIFT) & 1;
+            delivery_mode =
+                (entry >> IOAPIC_LVT_DELIV_MODE_SHIFT) & IOAPIC_DM_MASK;
+
+            msg.address = APIC_DEFAULT_ADDRESS;
+            msg.address |= dest_mode << 2;
+            msg.address |= dest << 12;
+
+            msg.data = entry & IOAPIC_VECTOR_MASK;
+            msg.data |= delivery_mode << APIC_DELIVERY_MODE_SHIFT;
+            msg.data |= pin_polarity << APIC_POLARITY_SHIFT;
+            msg.data |= trig_mode << APIC_TRIG_MODE_SHIFT;
+
+            kvm_irqchip_update_msi_route(kvm_state, i, msg, NULL);
+        }
+        kvm_irqchip_commit_routes(kvm_state);
+    }
+#endif
+}
+
 void ioapic_eoi_broadcast(int vector)
 {
     IOAPICCommonState *s;
@@ -229,6 +291,8 @@ ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val,
         }
         break;
     }
+
+    ioapic_update_kvm_routes(s);
 }
 
 static const MemoryRegionOps ioapic_io_ops = {