[PATCH v2] x86/APIC: Switch flat driver to use phys dst for ext ints

[Matthew Barnes <matthew.barnes@xxxxxxxxx>]

External interrupts via logical delivery mode in xAPIC do not benefit
from targeting multiple CPUs and instead simply bloat up the vector
space.

However the xAPIC flat driver currently uses logical delivery for
external interrupts.

This patch switches the xAPIC flat driver to use physical destination
mode for external interrupts, instead of logical destination mode.

This patch also applies the following non-functional changes:
- Remove now unused logical flat functions
- Expand GENAPIC_FLAT and GENAPIC_PHYS macros, and delete them.

Resolves: https://gitlab.com/xen-project/xen/-/issues/194
Signed-off-by: Matthew Barnes <matthew.barnes@xxxxxxxxx>
---
Changes in v2:
- Reword commit message
- Expand and delete GENAPIC_* macros
- Bundle patch series into one patch
---
 xen/arch/x86/genapic/bigsmp.c      |  8 +++++++-
 xen/arch/x86/genapic/default.c     |  8 +++++++-
 xen/arch/x86/genapic/delivery.c    | 10 ----------
 xen/arch/x86/include/asm/genapic.h | 20 +-------------------
 4 files changed, 15 insertions(+), 31 deletions(-)

diff --git a/xen/arch/x86/genapic/bigsmp.c b/xen/arch/x86/genapic/bigsmp.c
index e97e4453a033..b2e721845275 100644
--- a/xen/arch/x86/genapic/bigsmp.c
+++ b/xen/arch/x86/genapic/bigsmp.c
@@ -46,5 +46,11 @@ static int __init cf_check probe_bigsmp(void)
 
 const struct genapic __initconst_cf_clobber apic_bigsmp = {
        APIC_INIT("bigsmp", probe_bigsmp),
-       GENAPIC_PHYS
+       .int_delivery_mode = dest_Fixed,
+       .int_dest_mode = 0, /* physical delivery */
+       .init_apic_ldr = init_apic_ldr_phys,
+       .vector_allocation_cpumask = vector_allocation_cpumask_phys,
+       .cpu_mask_to_apicid = cpu_mask_to_apicid_phys,
+       .send_IPI_mask = send_IPI_mask_phys,
+       .send_IPI_self = send_IPI_self_legacy
 };
diff --git a/xen/arch/x86/genapic/default.c b/xen/arch/x86/genapic/default.c
index a968836a1878..59c79afdb8fa 100644
--- a/xen/arch/x86/genapic/default.c
+++ b/xen/arch/x86/genapic/default.c
@@ -16,5 +16,11 @@
 /* should be called last. */
 const struct genapic __initconst_cf_clobber apic_default = {
        APIC_INIT("default", NULL),
-       GENAPIC_FLAT
+       .int_delivery_mode = dest_Fixed,
+       .int_dest_mode = 0, /* physical delivery */
+       .init_apic_ldr = init_apic_ldr_flat,
+       .vector_allocation_cpumask = vector_allocation_cpumask_phys,
+       .cpu_mask_to_apicid = cpu_mask_to_apicid_phys,
+       .send_IPI_mask = send_IPI_mask_flat,
+       .send_IPI_self = send_IPI_self_legacy
 };
diff --git a/xen/arch/x86/genapic/delivery.c b/xen/arch/x86/genapic/delivery.c
index d1f99bf6834a..3def78f380d3 100644
--- a/xen/arch/x86/genapic/delivery.c
+++ b/xen/arch/x86/genapic/delivery.c
@@ -19,16 +19,6 @@ void cf_check init_apic_ldr_flat(void)
        apic_write(APIC_LDR, val);
 }
 
-const cpumask_t *cf_check vector_allocation_cpumask_flat(int cpu)
-{
-       return &cpu_online_map;
-} 
-
-unsigned int cf_check cpu_mask_to_apicid_flat(const cpumask_t *cpumask)
-{
-       return cpumask_bits(cpumask)[0]&0xFF;
-}
-
 /*
  * PHYSICAL DELIVERY MODE (unicast to physical APIC IDs).
  */
diff --git a/xen/arch/x86/include/asm/genapic.h 
b/xen/arch/x86/include/asm/genapic.h
index a694371c6d16..2f46f173c1d4 100644
--- a/xen/arch/x86/include/asm/genapic.h
+++ b/xen/arch/x86/include/asm/genapic.h
@@ -44,29 +44,11 @@ extern const struct genapic apic_bigsmp;
 void cf_check send_IPI_self_legacy(uint8_t vector);
 
 void cf_check init_apic_ldr_flat(void);
-unsigned int cf_check cpu_mask_to_apicid_flat(const cpumask_t *cpumask);
+const cpumask_t *cf_check vector_allocation_cpumask_phys(int cpu);
 void cf_check send_IPI_mask_flat(const cpumask_t *cpumask, int vector);
-const cpumask_t *cf_check vector_allocation_cpumask_flat(int cpu);
-#define GENAPIC_FLAT \
-       .int_delivery_mode = dest_LowestPrio, \
-       .int_dest_mode = 1 /* logical delivery */, \
-       .init_apic_ldr = init_apic_ldr_flat, \
-       .vector_allocation_cpumask = vector_allocation_cpumask_flat, \
-       .cpu_mask_to_apicid = cpu_mask_to_apicid_flat, \
-       .send_IPI_mask = send_IPI_mask_flat, \
-       .send_IPI_self = send_IPI_self_legacy
 
 void cf_check init_apic_ldr_phys(void);
 unsigned int cf_check cpu_mask_to_apicid_phys(const cpumask_t *cpumask);
 void cf_check send_IPI_mask_phys(const cpumask_t *mask, int vector);
-const cpumask_t *cf_check vector_allocation_cpumask_phys(int cpu);
-#define GENAPIC_PHYS \
-       .int_delivery_mode = dest_Fixed, \
-       .int_dest_mode = 0 /* physical delivery */, \
-       .init_apic_ldr = init_apic_ldr_phys, \
-       .vector_allocation_cpumask = vector_allocation_cpumask_phys, \
-       .cpu_mask_to_apicid = cpu_mask_to_apicid_phys, \
-       .send_IPI_mask = send_IPI_mask_phys, \
-       .send_IPI_self = send_IPI_self_legacy
 
 #endif
-- 
2.46.0