x86/apic: Switch all APICs to Fixed delivery mode

Some of the APIC incarnations are operating in lowest priority delivery
mode. This worked as long as the vector management code allocated the same
vector on all possible CPUs for each interrupt.

Lowest priority delivery mode does not necessarily respect the affinity
setting and may redirect to some other online CPU. This was documented
somewhere in the old code and the conversion to single target delivery
missed to update the delivery mode of the affected APIC drivers which
results in spurious interrupts on some of the affected CPU/Chipset
combinations.

Switch the APIC drivers over to Fixed delivery mode and remove all
leftovers of lowest priority delivery mode.

Switching to Fixed delivery mode is not a problem on these CPUs because the
kernel already uses Fixed delivery mode for IPIs. The reason for this is
that th SDM explicitely forbids lowest prio mode for IPIs. The reason is
obvious: If the irq routing does not honor destination targets in lowest
prio mode then an IPI targeted at CPU1 might end up on CPU0, which would be
a fatal problem in many cases.

As a consequence of this change, the apic::irq_delivery_mode field is now
pointless, but this needs to be cleaned up in a separate patch.

Fixes: fdba46ffb4c2 ("x86/apic: Get rid of multi CPU affinity")
Reported-by: vcaputo@pengaru.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: vcaputo@pengaru.com
Cc: Pavel Machek <pavel@ucw.cz>
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1712281140440.1688@nanos

6 files changed, 8 insertions, 16 deletions

diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index aa85690e9b641..25a87028cb3fe 100644
--- a/arch/x86/kernel/apic/apic_flat_64.c
+++ b/arch/x86/kernel/apic/apic_flat_64.c
@@ -151,7 +151,7 @@ static struct apic apic_flat __ro_after_init = {
 	.apic_id_valid			= default_apic_id_valid,
 	.apic_id_registered		= flat_apic_id_registered,
 
-	.irq_delivery_mode		= dest_LowestPrio,
+	.irq_delivery_mode		= dest_Fixed,
 	.irq_dest_mode			= 1, /* logical */
 
 	.disable_esr			= 0,
diff --git a/arch/x86/kernel/apic/apic_noop.c b/arch/x86/kernel/apic/apic_noop.c
index 7b659c4480c91..5078b5ce63a7a 100644
--- a/arch/x86/kernel/apic/apic_noop.c
+++ b/arch/x86/kernel/apic/apic_noop.c
@@ -110,7 +110,7 @@ struct apic apic_noop __ro_after_init = {
 	.apic_id_valid			= default_apic_id_valid,
 	.apic_id_registered		= noop_apic_id_registered,
 
-	.irq_delivery_mode		= dest_LowestPrio,
+	.irq_delivery_mode		= dest_Fixed,
 	/* logical delivery broadcast to all CPUs: */
 	.irq_dest_mode			= 1,
 
diff --git a/arch/x86/kernel/apic/msi.c b/arch/x86/kernel/apic/msi.c
index 9b18be7644223..ce503c99f5c4c 100644
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -39,17 +39,13 @@ static void irq_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
 		((apic->irq_dest_mode == 0) ?
 			MSI_ADDR_DEST_MODE_PHYSICAL :
 			MSI_ADDR_DEST_MODE_LOGICAL) |
-		((apic->irq_delivery_mode != dest_LowestPrio) ?
-			MSI_ADDR_REDIRECTION_CPU :
-			MSI_ADDR_REDIRECTION_LOWPRI) |
+		MSI_ADDR_REDIRECTION_CPU |
 		MSI_ADDR_DEST_ID(cfg->dest_apicid);
 
 	msg->data =
 		MSI_DATA_TRIGGER_EDGE |
 		MSI_DATA_LEVEL_ASSERT |
-		((apic->irq_delivery_mode != dest_LowestPrio) ?
-			MSI_DATA_DELIVERY_FIXED :
-			MSI_DATA_DELIVERY_LOWPRI) |
+		MSI_DATA_DELIVERY_FIXED |
 		MSI_DATA_VECTOR(cfg->vector);
 }
 
diff --git a/arch/x86/kernel/apic/probe_32.c b/arch/x86/kernel/apic/probe_32.c
index fa22017de8065..02e8acb134f85 100644
--- a/arch/x86/kernel/apic/probe_32.c
+++ b/arch/x86/kernel/apic/probe_32.c
@@ -105,7 +105,7 @@ static struct apic apic_default __ro_after_init = {
 	.apic_id_valid			= default_apic_id_valid,
 	.apic_id_registered		= default_apic_id_registered,
 
-	.irq_delivery_mode		= dest_LowestPrio,
+	.irq_delivery_mode		= dest_Fixed,
 	/* logical delivery broadcast to all CPUs: */
 	.irq_dest_mode			= 1,
 
diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index 622f13ca8a943..8b04234e010b2 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -184,7 +184,7 @@ static struct apic apic_x2apic_cluster __ro_after_init = {
 	.apic_id_valid			= x2apic_apic_id_valid,
 	.apic_id_registered		= x2apic_apic_id_registered,
 
-	.irq_delivery_mode		= dest_LowestPrio,
+	.irq_delivery_mode		= dest_Fixed,
 	.irq_dest_mode			= 1, /* logical */
 
 	.disable_esr			= 0,
diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 0fe3ea164ee53..e7d94473aedd0 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -985,9 +985,7 @@ static u32 hv_compose_msi_req_v1(
 	int_pkt->wslot.slot = slot;
 	int_pkt->int_desc.vector = vector;
 	int_pkt->int_desc.vector_count = 1;
-	int_pkt->int_desc.delivery_mode =
-		(apic->irq_delivery_mode == dest_LowestPrio) ?
-			dest_LowestPrio : dest_Fixed;
+	int_pkt->int_desc.delivery_mode = dest_Fixed;
 
 	/*
 	 * Create MSI w/ dummy vCPU set, overwritten by subsequent retarget in
@@ -1008,9 +1006,7 @@ static u32 hv_compose_msi_req_v2(
 	int_pkt->wslot.slot = slot;
 	int_pkt->int_desc.vector = vector;
 	int_pkt->int_desc.vector_count = 1;
-	int_pkt->int_desc.delivery_mode =
-		(apic->irq_delivery_mode == dest_LowestPrio) ?
-			dest_LowestPrio : dest_Fixed;
+	int_pkt->int_desc.delivery_mode = dest_Fixed;
 
 	/*
 	 * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten