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

diff --git a/arch/x86/kernel/apic/apic_flat_64.c b/arch/x86/kernel/apic/apic_flat_64.c
index aa85690e9b6416b797db8129c8f1cbd7606bf687..25a87028cb3fe9bb4a6e9eba757d50cd49f15620 100644 (file)
--- 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 7b659c4480c91a680466cc961cee68754c633ada..5078b5ce63a7aaf4569368e6447c9a4423271109 100644 (file)
--- 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 9b18be76442236eab971cab86cbf366f9e1e134f..ce503c99f5c4cd67fddb5fafdda7e3e64b8e7690 100644 (file)
--- 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 fa22017de806504b79593ead951bffe4e5d5421b..02e8acb134f856faa0030bf1c007dc3ac1bd9ca3 100644 (file)
--- 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 622f13ca8a943c270e70df6100561ce4c56d7db2..8b04234e010b2616e42bff6cbeabdc3c2087c13c 100644 (file)
--- 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 0fe3ea164ee53321b2a23aded63eeac6c68684fa..e7d94473aedd0b6c580e0581c18cdccd01946f2a 100644 (file)
--- 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