[PATCH 0/3] i386/kvm: Assume IRQ routing is always available

[PATCH 0/3] i386/kvm: Assume IRQ routing is always available

[Eduardo Habkost]

KVM_CAP_IRQ_ROUTING is available since 2019 (Linux v2.6.30), so
we can safely assume it's always present and remove some runtime
checks.

Eduardo Habkost (3):
  i386/kvm: Require KVM_CAP_IRQ_ROUTING
  i386/kvm: Remove IRQ routing support checks
  i386/kvm: Delete kvm_allows_irq0_override()

 target/i386/kvm_i386.h |  1 -
 hw/i386/fw_cfg.c       |  2 +-
 hw/i386/kvm/apic.c     |  5 ++---
 hw/i386/kvm/ioapic.c   | 33 ++++++++++++++++-----------------
 hw/i386/microvm.c      |  2 +-
 hw/i386/pc.c           |  2 +-
 target/i386/kvm-stub.c |  5 -----
 target/i386/kvm.c      | 17 +++++------------
 8 files changed, 26 insertions(+), 41 deletions(-)

-- 
2.26.2

[PATCH 1/3] i386/kvm: Require KVM_CAP_IRQ_ROUTING

[Eduardo Habkost]

KVM_CAP_IRQ_ROUTING is available since 2009 (Linux v2.6.30), so
it's safe to just make it a requirement on x86.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/kvm.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 9efb07e7c83..d884ff1b071 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -2129,6 +2129,11 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     int ret;
     struct utsname utsname;
 
+    if (!kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
+        error_report("kvm: KVM_CAP_IRQ_ROUTING not supported by KVM");
+        return -ENOTSUP;
+    }
+
     has_xsave = kvm_check_extension(s, KVM_CAP_XSAVE);
     has_xcrs = kvm_check_extension(s, KVM_CAP_XCRS);
     has_pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
-- 
2.26.2

[PATCH 2/3] i386/kvm: Remove IRQ routing support checks

[Eduardo Habkost]

KVM_CAP_IRQ_ROUTING is always available on x86, so replace checks
for kvm_has_gsi_routing() and KVM_CAP_IRQ_ROUTING with asserts.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 hw/i386/kvm/apic.c   |  5 ++---
 hw/i386/kvm/ioapic.c | 33 ++++++++++++++++-----------------
 target/i386/kvm.c    |  7 -------
 3 files changed, 18 insertions(+), 27 deletions(-)

diff --git a/hw/i386/kvm/apic.c b/hw/i386/kvm/apic.c
index 4eb2d77b87b..dd29906061c 100644
--- a/hw/i386/kvm/apic.c
+++ b/hw/i386/kvm/apic.c
@@ -225,9 +225,8 @@ static void kvm_apic_realize(DeviceState *dev, Error **errp)
     memory_region_init_io(&s->io_memory, OBJECT(s), &kvm_apic_io_ops, s,
                           "kvm-apic-msi", APIC_SPACE_SIZE);
 
-    if (kvm_has_gsi_routing()) {
-        msi_nonbroken = true;
-    }
+    assert(kvm_has_gsi_routing());
+    msi_nonbroken = true;
 }
 
 static void kvm_apic_unrealize(DeviceState *dev)
diff --git a/hw/i386/kvm/ioapic.c b/hw/i386/kvm/ioapic.c
index c5528df942a..dfc3c980057 100644
--- a/hw/i386/kvm/ioapic.c
+++ b/hw/i386/kvm/ioapic.c
@@ -25,27 +25,26 @@ void kvm_pc_setup_irq_routing(bool pci_enabled)
     KVMState *s = kvm_state;
     int i;
 
-    if (kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
-        for (i = 0; i < 8; ++i) {
-            if (i == 2) {
-                continue;
-            }
-            kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_PIC_MASTER, i);
-        }
-        for (i = 8; i < 16; ++i) {
-            kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_PIC_SLAVE, i - 8);
+    assert(kvm_has_gsi_routing());
+    for (i = 0; i < 8; ++i) {
+        if (i == 2) {
+            continue;
         }
-        if (pci_enabled) {
-            for (i = 0; i < 24; ++i) {
-                if (i == 0) {
-                    kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_IOAPIC, 2);
-                } else if (i != 2) {
-                    kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_IOAPIC, i);
-                }
+        kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_PIC_MASTER, i);
+    }
+    for (i = 8; i < 16; ++i) {
+        kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_PIC_SLAVE, i - 8);
+    }
+    if (pci_enabled) {
+        for (i = 0; i < 24; ++i) {
+            if (i == 0) {
+                kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_IOAPIC, 2);
+            } else if (i != 2) {
+                kvm_irqchip_add_irq_route(s, i, KVM_IRQCHIP_IOAPIC, i);
             }
         }
-        kvm_irqchip_commit_routes(s);
     }
+    kvm_irqchip_commit_routes(s);
 }
 
 typedef struct KVMIOAPICState KVMIOAPICState;
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index d884ff1b071..cf6dc90f7c5 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -4558,13 +4558,6 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cs)
 
 void kvm_arch_init_irq_routing(KVMState *s)
 {
-    if (!kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
-        /* If kernel can't do irq routing, interrupt source
-         * override 0->2 cannot be set up as required by HPET.
-         * So we have to disable it.
-         */
-        no_hpet = 1;
-    }
     /* We know at this point that we're using the in-kernel
      * irqchip, so we can use irqfds, and on x86 we know
      * we can use msi via irqfd and GSI routing.
-- 
2.26.2

[PATCH 3/3] i386/kvm: Delete kvm_allows_irq0_override()

[Eduardo Habkost]

As IRQ routing is always available on x86,
kvm_allows_irq0_override() will always return true, so we don't
need the function anymore.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 target/i386/kvm_i386.h | 1 -
 hw/i386/fw_cfg.c       | 2 +-
 hw/i386/microvm.c      | 2 +-
 hw/i386/pc.c           | 2 +-
 target/i386/kvm-stub.c | 5 -----
 target/i386/kvm.c      | 5 -----
 6 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 064b8798a26..b11704cc772 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -32,7 +32,6 @@
 
 #endif  /* CONFIG_KVM */
 
-bool kvm_allows_irq0_override(void);
 bool kvm_has_smm(void);
 bool kvm_has_adjust_clock_stable(void);
 bool kvm_has_exception_payload(void);
diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index 33441ad4840..e06579490c4 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -123,7 +123,7 @@ FWCfgState *fw_cfg_arch_create(MachineState *ms,
     fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES,
                      acpi_tables, acpi_tables_len);
 #endif
-    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, kvm_allows_irq0_override());
+    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, 1);
 
     fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE,
                      &e820_reserve, sizeof(e820_reserve));
diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
index 60d32722301..05fb0536dcc 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -225,7 +225,7 @@ static void microvm_memory_init(MicrovmMachineState *mms)
     fw_cfg_add_i16(fw_cfg, FW_CFG_NB_CPUS, machine->smp.cpus);
     fw_cfg_add_i16(fw_cfg, FW_CFG_MAX_CPUS, machine->smp.max_cpus);
     fw_cfg_add_i64(fw_cfg, FW_CFG_RAM_SIZE, (uint64_t)machine->ram_size);
-    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, kvm_allows_irq0_override());
+    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, 1);
     fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE,
                      &e820_reserve, sizeof(e820_reserve));
     fw_cfg_add_file(fw_cfg, "etc/e820", e820_table,
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index b55369357e5..0bc569d4c6b 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -859,7 +859,7 @@ void pc_guest_info_init(PCMachineState *pcms)
     MachineState *ms = MACHINE(pcms);
     X86MachineState *x86ms = X86_MACHINE(pcms);
 
-    x86ms->apic_xrupt_override = kvm_allows_irq0_override();
+    x86ms->apic_xrupt_override = true;
     pcms->numa_nodes = ms->numa_state->num_nodes;
     pcms->node_mem = g_malloc0(pcms->numa_nodes *
                                     sizeof *pcms->node_mem);
diff --git a/target/i386/kvm-stub.c b/target/i386/kvm-stub.c
index 872ef7df4c8..92f49121b8f 100644
--- a/target/i386/kvm-stub.c
+++ b/target/i386/kvm-stub.c
@@ -13,11 +13,6 @@
 #include "cpu.h"
 #include "kvm_i386.h"
 
-bool kvm_allows_irq0_override(void)
-{
-    return 1;
-}
-
 #ifndef __OPTIMIZE__
 bool kvm_has_smm(void)
 {
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index cf6dc90f7c5..c419c52ec58 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -148,11 +148,6 @@ bool kvm_has_exception_payload(void)
     return has_exception_payload;
 }
 
-bool kvm_allows_irq0_override(void)
-{
-    return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
-}
-
 static bool kvm_x2apic_api_set_flags(uint64_t flags)
 {
     KVMState *s = KVM_STATE(current_accel());
-- 
2.26.2

Re: [PATCH 0/3] i386/kvm: Assume IRQ routing is always available

[Paolo Bonzini]

On 22/09/20 22:19, Eduardo Habkost wrote:
> KVM_CAP_IRQ_ROUTING is available since 2019 (Linux v2.6.30), so
> we can safely assume it's always present and remove some runtime
> checks.
> 
> Eduardo Habkost (3):
>   i386/kvm: Require KVM_CAP_IRQ_ROUTING
>   i386/kvm: Remove IRQ routing support checks
>   i386/kvm: Delete kvm_allows_irq0_override()
> 
>  target/i386/kvm_i386.h |  1 -
>  hw/i386/fw_cfg.c       |  2 +-
>  hw/i386/kvm/apic.c     |  5 ++---
>  hw/i386/kvm/ioapic.c   | 33 ++++++++++++++++-----------------
>  hw/i386/microvm.c      |  2 +-
>  hw/i386/pc.c           |  2 +-
>  target/i386/kvm-stub.c |  5 -----
>  target/i386/kvm.c      | 17 +++++------------
>  8 files changed, 26 insertions(+), 41 deletions(-)
> 

Acked-by: Paolo Bonzini <pbonzini@redhat.com>