[PATCH] KVM: Implement support for the RH bit

[Sasha Levin <levinsasha928@gmail.com>]

The RH bit exists in the message address register (lower 32 bits of
the address).

The bit indicates whether the message should go to the processor which was
indicated in the destination ID bits, or whether it should go to the
processor running at the lowest priority.

Cc: Avi Kivity <avi@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 arch/x86/kvm/lapic.c      |   17 +++++++++++++++--
 include/linux/kvm_types.h |    1 +
 virt/kvm/ioapic.h         |    2 +-
 virt/kvm/irq_comm.c       |   14 +++++++++++---
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 57dcbd4..3347f9f 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -33,6 +33,7 @@
 #include <asm/page.h>
 #include <asm/current.h>
 #include <asm/apicdef.h>
+#include <asm/msidef.h>
 #include <linux/atomic.h>
 #include "kvm_cache_regs.h"
 #include "irq.h"
@@ -325,7 +326,7 @@ int kvm_apic_match_logical_addr(struct kvm_lapic *apic, u8 mda)
 }
 
 int kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
-			   int short_hand, int dest, int dest_mode)
+			   int short_hand, int dest, int dest_mode, int rh)
 {
 	int result = 0;
 	struct kvm_lapic *target = vcpu->arch.apic;
@@ -335,9 +336,21 @@ int kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
 		   target, source, dest, dest_mode, short_hand);
 
 	ASSERT(target);
+
+	/* If RH bit is not set, use addressing mode from ICR */
+	if (rh == 0) {
+		u32 icr_low = apic_get_reg(target, APIC_ICR);
+
+		dest_mode = icr_low & APIC_DEST_MASK;
+
+		/* dest apic can't be 0xff if targeting specific processor */
+		BUG_ON(dest_mode == MSI_ADDR_DEST_MODE_PHYSICAL &&
+			(u8)dest == 0xff);
+	}
+
 	switch (short_hand) {
 	case APIC_DEST_NOSHORT:
-		if (dest_mode == 0)
+		if (dest_mode == MSI_ADDR_DEST_MODE_PHYSICAL)
 			/* Physical mode. */
 			result = kvm_apic_match_physical_addr(target, dest);
 		else
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index fa7cc72..55d4d9a 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -65,6 +65,7 @@ struct kvm_lapic_irq {
 	u32 trig_mode;
 	u32 shorthand;
 	u32 dest_id;
+	u32 redir_hint;
 };
 
 struct gfn_to_hva_cache {
diff --git a/virt/kvm/ioapic.h b/virt/kvm/ioapic.h
index 0b190c3..fd3bb64 100644
--- a/virt/kvm/ioapic.h
+++ b/virt/kvm/ioapic.h
@@ -68,7 +68,7 @@ static inline struct kvm_ioapic *ioapic_irqchip(struct kvm *kvm)
 }
 
 int kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
-		int short_hand, int dest, int dest_mode);
+		   int short_hand, int dest, int dest_mode, int rh);
 int kvm_apic_compare_prio(struct kvm_vcpu *vcpu1, struct kvm_vcpu *vcpu2);
 void kvm_ioapic_update_eoi(struct kvm *kvm, int vector, int trigger_mode);
 int kvm_ioapic_init(struct kvm *kvm);
diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
index 9f614b4..e53fc83 100644
--- a/virt/kvm/irq_comm.c
+++ b/virt/kvm/irq_comm.c
@@ -68,6 +68,11 @@ static int kvm_set_ioapic_irq(struct kvm_kernel_irq_routing_entry *e,
 	return kvm_ioapic_set_irq(ioapic, e->irqchip.pin, level);
 }
 
+static inline bool kvm_is_rh_lowest_prio(struct kvm_lapic_irq *irq)
+{
+	return irq->redir_hint == MSI_ADDR_REDIRECTION_LOWPRI;
+}
+
 inline static bool kvm_is_dm_lowest_prio(struct kvm_lapic_irq *irq)
 {
 #ifdef CONFIG_IA64
@@ -93,10 +98,12 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 			continue;
 
 		if (!kvm_apic_match_dest(vcpu, src, irq->shorthand,
-					irq->dest_id, irq->dest_mode))
+					irq->dest_id, irq->dest_mode,
+					irq->redir_hint))
 			continue;
 
-		if (!kvm_is_dm_lowest_prio(irq)) {
+		if (!kvm_is_dm_lowest_prio(irq) &&
+		    !kvm_is_rh_lowest_prio(irq)) {
 			if (r < 0)
 				r = 0;
 			r += kvm_apic_set_irq(vcpu, irq);
@@ -128,13 +135,14 @@ int kvm_set_msi(struct kvm_kernel_irq_routing_entry *e,
 			MSI_ADDR_DEST_ID_MASK) >> MSI_ADDR_DEST_ID_SHIFT;
 	irq.vector = (e->msi.data &
 			MSI_DATA_VECTOR_MASK) >> MSI_DATA_VECTOR_SHIFT;
+
+	irq.redir_hint = (1 << MSI_ADDR_REDIRECTION_SHIFT) & e->msi.address_lo;
 	irq.dest_mode = (1 << MSI_ADDR_DEST_MODE_SHIFT) & e->msi.address_lo;
 	irq.trig_mode = (1 << MSI_DATA_TRIGGER_SHIFT) & e->msi.data;
 	irq.delivery_mode = e->msi.data & 0x700;
 	irq.level = 1;
 	irq.shorthand = 0;
 
-	/* TODO Deal with RH bit of MSI message address */
 	return kvm_irq_delivery_to_apic(kvm, NULL, &irq);
 }
 
-- 
1.7.6.1