[RFC][PATCH 1/2] Make irq0->inti2 override in BIOS configurable from userspace

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This series of patches (nearly) resolves the irq0->inti2 override issue, and gets the hpet working on kvm with and
without the in-kernel irqchip (i.e., it disables userspace and in-kernel pit as needed).

- irq0->inti2
  The resolution was to always use the override unless the kernel cannot do irq routing (i.e., compatibility with old
  kernels). So qemu checks whether the kernel is capable of irq routing. If so, qemu tells kvm to route irq0 to 
  inti2 via the irq routing interface, and tells bios to add the irq0->inti2 override to the MADT interrupt source 
  override table, and to the mp table (for the non-acpi case). The only outstanding problem here is that when I set 
  acpi=off on the kernel boot line, the boot fails. Apparently linux does not like the way I implemented the override 
  for the mp table in rombios32.c. Since I am pressed for time at the moment, I'm putting this patch set out for comments 
  in hopes that someone else may immediately see the problem. Otherwise  I'll keep looking into it as time permits.

- hpet
  The hpet works with and without in-kernel irqchip. And many thanks to Marcelo for finding a bios corruption bug that
  was the primary source of win2k864 problems. Now the hpet works on linux (ubuntu 8.0.4), win2k832. On win2k864 it works
  with the in-kernel irqchip but is broken (i.e.,black screen) when -no-kvm-irqchip is specified. Though I found that 
  it is also broken when I remove these 2 patches, so it appears to have nothing to do with hpet or irq routing. Needs 
  more looking into.


Signed-off-by: Beth Kon <eak@xxxxxxxxxx>
---
 bios/Makefile    |    2 +-
 bios/rombios32.c |   40 ++++++++++++++++++++++++++++++++++++----
 qemu/hw/apic.c   |    5 ++---
 qemu/hw/fw_cfg.c |    1 +
 qemu/hw/fw_cfg.h |    1 +
 qemu/qemu-kvm.c  |    5 ++++-
 qemu/sysemu.h    |    1 +
 qemu/vl.c        |   10 ++++++++--
 8 files changed, 54 insertions(+), 11 deletions(-)

diff --git a/bios/Makefile b/bios/Makefile
index 2d1f40d..374d70e 100644
--- a/bios/Makefile
+++ b/bios/Makefile
@@ -48,7 +48,7 @@ LIBS =  -lm
 RANLIB = ranlib
 
 BCC = bcc
-GCC = gcc $(CFLAGS)
+GCC = gcc $(CFLAGS) -fno-stack-protector
 HOST_CC = gcc
 AS86 = as86
 
diff --git a/bios/rombios32.c b/bios/rombios32.c
index 9d2eaaa..84f15fb 100755
--- a/bios/rombios32.c
+++ b/bios/rombios32.c
@@ -443,6 +443,7 @@ uint32_t cpuid_ext_features;
 unsigned long ram_size;
 uint64_t ram_end;
 uint8_t bios_uuid[16];
+uint8_t irq0_override;
 #ifdef BX_USE_EBDA_TABLES
 unsigned long ebda_cur_addr;
 #endif
@@ -475,6 +476,7 @@ void wrmsr_smp(uint32_t index, uint64_t val)
 #define QEMU_CFG_SIGNATURE  0x00
 #define QEMU_CFG_ID         0x01
 #define QEMU_CFG_UUID       0x02
+#define QEMU_CFG_IRQ0_OVERRIDE 0x07
 
 int qemu_cfg_port;
 
@@ -516,6 +518,18 @@ void uuid_probe(void)
     memset(bios_uuid, 0, 16);
 }
 
+void irq0_override_probe(void)
+{
+#ifdef BX_QEMU
+    if(qemu_cfg_port) {
+        qemu_cfg_select(QEMU_CFG_IRQ0_OVERRIDE);
+        qemu_cfg_read(&irq0_override, 1);
+        return;
+    }
+#endif
+    memset(&irq0_override, 0, 1);
+}
+
 void cpu_probe(void)
 {
     uint32_t eax, ebx, ecx, edx;
@@ -1149,6 +1163,8 @@ static void mptable_init(void)
 
     /* irqs */
     for(i = 0; i < 16; i++) {
+        if (irq0_override && i == 2)
+            continue;
         putb(&q, 3); /* entry type = I/O interrupt */
         putb(&q, 0); /* interrupt type = vectored interrupt */
         putb(&q, 0); /* flags: po=0, el=0 */
@@ -1156,7 +1172,10 @@ static void mptable_init(void)
         putb(&q, 0); /* source bus ID = ISA */
         putb(&q, i); /* source bus IRQ */
         putb(&q, ioapic_id); /* dest I/O APIC ID */
-        putb(&q, i); /* dest I/O APIC interrupt in */
+        if (irq0_override && i == 0)
+            putb(&q, 2); /* dest I/O APIC interrupt in */
+        else 
+            putb(&q, i); /* dest I/O APIC interrupt in */
     }
     /* patch length */
     len = q - mp_config_table;
@@ -1505,6 +1524,11 @@ void acpi_bios_init(void)
         sizeof(struct madt_processor_apic) * MAX_CPUS +
         sizeof(struct madt_io_apic);
     madt = (void *)(addr);
+    for (i = 0; i < 16; i++)
+        if (PCI_ISA_IRQ_MASK & (1U << i))
+            madt_size += sizeof(struct madt_intsrcovr);
+    if (irq0_override)
+        madt_size += sizeof(struct madt_intsrcovr);
     addr += madt_size;
 
     acpi_tables_size = addr - base_addr;
@@ -1594,8 +1618,15 @@ void acpi_bios_init(void)
         io_apic->interrupt = cpu_to_le32(0);
 
         intsrcovr = (struct madt_intsrcovr*)(io_apic + 1);
-        for ( i = 0; i < 16; i++ ) {
-            if ( PCI_ISA_IRQ_MASK & (1U << i) ) {
+        for (i = 0; i < 16; i++) {
+            if (irq0_override && i == 0) {
+                memset(intsrcovr, 0, sizeof(*intsrcovr));
+                intsrcovr->type   = APIC_XRUPT_OVERRIDE;
+                intsrcovr->length = sizeof(*intsrcovr);
+                intsrcovr->source = i;
+                intsrcovr->gsi    = 2;
+                intsrcovr->flags  = 0;  //conforms to bus specifications
+            } else if (PCI_ISA_IRQ_MASK & (1U << i)) {
                 memset(intsrcovr, 0, sizeof(*intsrcovr));
                 intsrcovr->type   = APIC_XRUPT_OVERRIDE;
                 intsrcovr->length = sizeof(*intsrcovr);
@@ -1607,7 +1638,6 @@ void acpi_bios_init(void)
                 continue;
             }
             intsrcovr++;
-            madt_size += sizeof(struct madt_intsrcovr);
         }
         acpi_build_table_header((struct acpi_table_header *)madt,
                                 "APIC", madt_size, 1);
@@ -2232,6 +2262,8 @@ void rombios32_init(uint32_t *s3_resume_vector, uint8_t *shutdown_flag)
         uuid_probe();
 
         smbios_init();
+ 
+        irq0_override_probe();
 
         if (acpi_enabled)
             acpi_bios_init();
diff --git a/qemu/hw/apic.c b/qemu/hw/apic.c
index 782b398..f28a103 100644
--- a/qemu/hw/apic.c
+++ b/qemu/hw/apic.c
@@ -19,6 +19,7 @@
  */
 #include "hw.h"
 #include "pc.h"
+#include "sysemu.h"
 #include "qemu-timer.h"
 #include "host-utils.h"
 
@@ -1077,14 +1078,12 @@ void ioapic_set_irq(void *opaque, int vector, int level)
 {
     IOAPICState *s = opaque;
 
-#if 0
     /* ISA IRQs map to GSI 1-1 except for IRQ0 which maps
      * to GSI 2.  GSI maps to ioapic 1-1.  This is not
      * the cleanest way of doing it but it should work. */
 
-    if (vector == 0)
+    if (vector == 0 && irq0override)
         vector = 2;
-#endif
 
     if (vector >= 0 && vector < IOAPIC_NUM_PINS) {
         uint32_t mask = 1 << vector;
diff --git a/qemu/hw/fw_cfg.c b/qemu/hw/fw_cfg.c
index 4333ed9..1b31ad2 100644
--- a/qemu/hw/fw_cfg.c
+++ b/qemu/hw/fw_cfg.c
@@ -287,6 +287,7 @@ void *fw_cfg_init(uint32_t ctl_port, uint32_t data_port,
     fw_cfg_add_bytes(s, FW_CFG_UUID, qemu_uuid, 16);
     fw_cfg_add_i16(s, FW_CFG_NOGRAPHIC, (uint16_t)nographic);
     fw_cfg_add_i16(s, FW_CFG_NB_CPUS, (uint16_t)smp_cpus);
+    fw_cfg_add_i16(s, FW_CFG_IRQ0_OVERRIDE, (uint16_t)irq0override);
 
     register_savevm("fw_cfg", -1, 1, fw_cfg_save, fw_cfg_load, s);
     qemu_register_reset(fw_cfg_reset, s);
diff --git a/qemu/hw/fw_cfg.h b/qemu/hw/fw_cfg.h
index ef8f378..a4e81d2 100644
--- a/qemu/hw/fw_cfg.h
+++ b/qemu/hw/fw_cfg.h
@@ -8,6 +8,7 @@
 #define FW_CFG_NOGRAPHIC        0x04
 #define FW_CFG_NB_CPUS          0x05
 #define FW_CFG_MACHINE_ID       0x06
+#define FW_CFG_IRQ0_OVERRIDE    0x07
 #define FW_CFG_MAX_ENTRY        0x10
 
 #define FW_CFG_WRITE_CHANNEL    0x4000
diff --git a/qemu/qemu-kvm.c b/qemu/qemu-kvm.c
index 5ff63ad..e32b4c2 100644
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -815,7 +815,10 @@ int kvm_qemu_create_context(void)
                 return r;
         }
         for (i = 0; i < 24; ++i) {
-            r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_IOAPIC, i);
+            if (i == 0)
+                r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_IOAPIC, 2);
+            else
+                r = kvm_add_irq_route(kvm_context, i, KVM_IRQCHIP_IOAPIC, i);
             if (r < 0)
                 return r;
         }
diff --git a/qemu/sysemu.h b/qemu/sysemu.h
index c8f268e..04db217 100644
--- a/qemu/sysemu.h
+++ b/qemu/sysemu.h
@@ -92,6 +92,7 @@ extern int graphic_width;
 extern int graphic_height;
 extern int graphic_depth;
 extern int nographic;
+extern int irq0override;
 extern const char *keyboard_layout;
 extern int win2k_install_hack;
 extern int rtc_td_hack;
diff --git a/qemu/vl.c b/qemu/vl.c
index 9557a06..21b3e51 100644
--- a/qemu/vl.c
+++ b/qemu/vl.c
@@ -194,6 +194,7 @@ static int vga_ram_size;
 enum vga_retrace_method vga_retrace_method = VGA_RETRACE_DUMB;
 static DisplayState *display_state;
 int nographic;
+int irq0override;
 static int curses;
 static int sdl;
 const char* keyboard_layout = NULL;
@@ -4874,6 +4875,7 @@ int main(int argc, char **argv, char **envp)
 #endif
     snapshot = 0;
     nographic = 0;
+    irq0override = 1;
     curses = 0;
     kernel_filename = NULL;
     kernel_cmdline = "";
@@ -5871,8 +5873,12 @@ int main(int argc, char **argv, char **envp)
         }
     }
 
-    if (kvm_enabled())
-	kvm_init_ap();
+    if (kvm_enabled()) {
+       kvm_init_ap();
+        if (kvm_irqchip && !kvm_has_gsi_routing(kvm_context)) {
+           irq0override = 0;
+        }
+    }
 
     machine->init(ram_size, vga_ram_size, boot_devices,
                   kernel_filename, kernel_cmdline, initrd_filename, cpu_model);
--
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