[v2,2/2] Deliver to only lowest prio cpu if msi_redir_hint is true

Commit Message

James Sullivan March 16, 2015, 5:29 p.m. UTC

Signed-off-by: James Sullivan <[e-mail]>
---

The following changes are added in this patch:
    * Move kvm_is_dm_lowest_prio() -> lapic.h, rename to
        kvm_lowest_prio_delivery, set condition to
        (APIC_DM_LOWPRI || msi_redir_hint)
    * Change check in kvm_irq_delivery_to_apic_fast() for
        APIC_DM_LOWPRI or msi_redir_hint to a check for
        kvm_is_dm_lowest_prio() 
Changes since v1:
    * Squashed a number of smaller commits into this one commit,
        which implements MSI delivery to only the lowest-priority
        CPU whenever RH=1 using the above helper
        kvm_lowest_prio_delivery().

This patch relies on a past submission that adds a check to
kvm_set_msi_irq() for RH=1, setting APIC_DEST_LOGICAL only when
RH=1/DM=1 and otherwise defaulting to APIC_DEST_PHYSICAL.
(See <[e-mail]>)

 arch/x86/kvm/irq_comm.c | 11 ++++-------
 arch/x86/kvm/lapic.c    |  3 +--
 arch/x86/kvm/lapic.h    |  6 ++++++
 3 files changed, 11 insertions(+), 9 deletions(-)

Patch

diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 5c33cca..69cdaab 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -31,6 +31,8 @@ 
 
 #include "ioapic.h"
 
+#include "lapic.h"
+
 static int kvm_set_pic_irq(struct kvm_kernel_irq_routing_entry *e,
 			   struct kvm *kvm, int irq_source_id, int level,
 			   bool line_status)
@@ -48,11 +50,6 @@  static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
 				line_status);
 }
 
-inline static bool kvm_is_dm_lowest_prio(struct kvm_lapic_irq *irq)
-{
-	return irq->delivery_mode == APIC_DM_LOWEST;
-}
-
 int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 		struct kvm_lapic_irq *irq, unsigned long *dest_map)
 {
@@ -60,7 +57,7 @@  int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 	struct kvm_vcpu *vcpu, *lowest = NULL;
 
 	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
-			kvm_is_dm_lowest_prio(irq)) {
+			kvm_lowest_prio_delivery(irq)) {
 		printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
 		irq->delivery_mode = APIC_DM_FIXED;
 	}
@@ -76,7 +73,7 @@  int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 					irq->dest_id, irq->dest_mode))
 			continue;
 
-		if (!kvm_is_dm_lowest_prio(irq)) {
+		if (!kvm_lowest_prio_delivery(irq)) {
 			if (r < 0)
 				r = 0;
 			r += kvm_apic_set_irq(vcpu, irq, dest_map);
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a15c444..f8b21d5 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -701,8 +701,7 @@  bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 		dst = map->logical_map[cid];
 
 		bitmap = apic_logical_id(map, mda);
-
-		if (irq->delivery_mode == APIC_DM_LOWEST) {
+		if (kvm_lowest_prio_delivery(irq)) {
 			int l = -1;
 			for_each_set_bit(i, &bitmap, 16) {
 				if (!dst[i])
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 0bc6c65..ed7e2fa 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -168,6 +168,12 @@  static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu)
 	return vcpu->arch.apic->pending_events;
 }
 
+static inline bool kvm_lowest_prio_delivery(struct kvm_lapic_irq *irq)
+{
+	return (irq->delivery_mode == APIC_DM_LOWEST ||
+			irq->msi_redir_hint);
+}
+
 bool kvm_apic_pending_eoi(struct kvm_vcpu *vcpu, int vector);
 
 void wait_lapic_expire(struct kvm_vcpu *vcpu);