[Qemu-devel] [PATCH] Seabios irq override support.

[Qemu-devel] [PATCH] Seabios irq override support.

[Jes Sorensen]

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Hi Kevin,

Here is a patch to implement irq override for timer interrupts from irq0
to int2. It's based on what Beth Kon implemented for BOCHS earlier, git
commit c6d25871212c05af647eccaad6efc07a6f7a4acb.

With this patch applied, I can boot KVM using the latest upstream QEMU
and Seabios.

Cheers,
Jes


[-- Attachment #2: 0004-irq-override.patch --]
[-- Type: text/x-patch, Size: 2476 bytes --]

Implement irq override support for timer interrupts. This matches what
QEMU+BOCHS has been doing for the latest 8 months, and is also what
real hardware does.

Windows expects this according to Beth Kon.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 src/acpi.c    |   10 ++++++++++
 src/mptable.c |   16 +++++++++++++---
 2 files changed, 23 insertions(+), 3 deletions(-)

Index: seabios/src/acpi.c
===================================================================
--- seabios.orig/src/acpi.c
+++ seabios/src/acpi.c
@@ -440,6 +440,16 @@ void acpi_bios_init(void)
     io_apic->interrupt = cpu_to_le32(0);
 
     struct madt_intsrcovr *intsrcovr = (void*)&io_apic[1];
+
+    memset(intsrcovr, 0, sizeof(*intsrcovr));
+    intsrcovr->type   = APIC_XRUPT_OVERRIDE;
+    intsrcovr->length = sizeof(*intsrcovr);
+    intsrcovr->source = 0;
+    intsrcovr->gsi    = 2;
+    intsrcovr->flags  = 0; /* conforms to bus specifications */
+    intsrcovr++;
+    madt_size += sizeof(struct madt_intsrcovr);
+
     for (i = 0; i < 16; i++) {
         if (!(PCI_ISA_IRQ_MASK & (1 << i)))
             /* No need for a INT source override structure. */
Index: seabios/src/mptable.c
===================================================================
--- seabios.orig/src/mptable.c
+++ seabios/src/mptable.c
@@ -29,7 +29,7 @@ mptable_init(void)
                   + sizeof(struct mpt_cpu) * smp_cpus
                   + sizeof(struct mpt_bus)
                   + sizeof(struct mpt_ioapic)
-                  + sizeof(struct mpt_intsrc) * 16);
+                  + sizeof(struct mpt_intsrc) * 15);
     if (start + length > bios_table_end_addr) {
         dprintf(1, "No room for MPTABLE!\n");
         return;
@@ -96,13 +96,23 @@ mptable_init(void)
 
     /* irqs */
     struct mpt_intsrc *intsrcs = (void *)&ioapic[1];
+    int j = 0;
     for(i = 0; i < 16; i++) {
-        struct mpt_intsrc *isrc = &intsrcs[i];
+        /* One entry per ioapic interrupt destination. Destination 2 is covered
+           by irq0->inti2 override (i == 0). Source IRQ 2 is unused */
+        if (i == 2) {
+            j = 1;
+            continue;
+        }
+        struct mpt_intsrc *isrc = &intsrcs[i - j];
         memset(isrc, 0, sizeof(*isrc));
         isrc->type = MPT_TYPE_INTSRC;
         isrc->srcbusirq = i;
         isrc->dstapic = ioapic_id;
-        isrc->dstirq = i;
+        if (i == 0)
+	    isrc->dstirq = 2;
+        else
+	    isrc->dstirq = i;
     }
 
     // Set checksum.

[Qemu-devel] Re: [PATCH] Seabios irq override support.

[Kevin O'Connor]

On Fri, Jul 24, 2009 at 03:07:12PM +0200, Jes Sorensen wrote:
> Hi Kevin,
>
> Here is a patch to implement irq override for timer interrupts from irq0
> to int2. It's based on what Beth Kon implemented for BOCHS earlier, git
> commit c6d25871212c05af647eccaad6efc07a6f7a4acb.
>
> With this patch applied, I can boot KVM using the latest upstream QEMU
> and Seabios.

Thanks Jes.

The bochs commit shows this wrapped in "#ifdef BX_QEMU".  Will this
patch break bochs, or were the ifdefs just bochs paranoia?

-Kevin

[Qemu-devel] Re: [PATCH] Seabios irq override support.

[Jes Sorensen]

On 07/25/2009 03:56 AM, Kevin O'Connor wrote:
> On Fri, Jul 24, 2009 at 03:07:12PM +0200, Jes Sorensen wrote:
>> With this patch applied, I can boot KVM using the latest upstream QEMU
>> and Seabios.
>
> Thanks Jes.
>
> The bochs commit shows this wrapped in "#ifdef BX_QEMU".  Will this
> patch break bochs, or were the ifdefs just bochs paranoia?

Hi Kevin,

I don't actually know for sure. I didn't add the #ifdefs since I got the
impression that Seabios doesn't have them in many places. The original
code was designed by Beth Kon, so maybe she can comment on whether we
should add them to Seabios.

Beth?

Thanks,
Jes

[Qemu-devel] Re: [PATCH] Seabios irq override support.

[Beth Kon]

Jes Sorensen wrote:
> On 07/25/2009 03:56 AM, Kevin O'Connor wrote:
>> On Fri, Jul 24, 2009 at 03:07:12PM +0200, Jes Sorensen wrote:
>>> With this patch applied, I can boot KVM using the latest upstream QEMU
>>> and Seabios.
>>
>> Thanks Jes.
>>
>> The bochs commit shows this wrapped in "#ifdef BX_QEMU".  Will this
>> patch break bochs, or were the ifdefs just bochs paranoia?
>
> Hi Kevin,
>
> I don't actually know for sure. I didn't add the #ifdefs since I got the
> impression that Seabios doesn't have them in many places. The original
> code was designed by Beth Kon, so maybe she can comment on whether we
> should add them to Seabios.
>
> Beth?
>
> Thanks,
> Jes
Hi Jes. These bios changes rely on matching userspace/kernel changes 
that translate irq0->inti2. So assuming seabios is used for systems 
other than kvm and qemu, this code would need to be conditionally removed.

But I'm not clear on what you're doing with this patch. You didn't 
include the irq0override flag that is needed by kvm because there are 
circumstances under which kvm turns off irq0override (i.e., old kernels 
that don't support irq routing). So this patch is fine for qemu, since 
it is permanently enabled there, but it is not a permanent solution for kvm.

[Qemu-devel] Re: [PATCH] Seabios irq override support.

[Jes Sorensen]

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On 07/27/2009 08:47 PM, Beth Kon wrote:
> Hi Jes. These bios changes rely on matching userspace/kernel changes
> that translate irq0->inti2. So assuming seabios is used for systems
> other than kvm and qemu, this code would need to be conditionally removed.

Hi Beth,

Thanks for the input. I guess we'll want it to be CONFIG_KVM for now
then, since Seabios doesn't know of BX_QEMU. Once we have more of the
cfg_fw stuff needed for this, the #ifdef part can be made prettier.

> But I'm not clear on what you're doing with this patch. You didn't
> include the irq0override flag that is needed by kvm because there are
> circumstances under which kvm turns off irq0override (i.e., old kernels
> that don't support irq routing). So this patch is fine for qemu, since
> it is permanently enabled there, but it is not a permanent solution for
> kvm.

The reason I didn't include the irq0override flag is that the fw_cfg
bits for this aren't in Seabios yet. I'll be happy to add them in a
follow up patch.

How do you like this version? It's a little more complex as I introduced
the irq0override variable, but it will make it very easy to add the
cfg_fw stuff.

Cheers,
Jes

[-- Attachment #2: 0004-irq-override-v2.patch --]
[-- Type: text/x-patch, Size: 3208 bytes --]

Implement irq override support for timer interrupts. This matches what
QEMU+BOCHS has been doing for the latest 8 months, and is also what
real hardware does.

Windows expects this according to Beth Kon.

Signed-off-by: Jes Sorensen <jes@sgi.com>

---
 src/acpi.c    |   12 ++++++++++++
 src/mptable.c |   26 +++++++++++++++++++++++---
 src/util.h    |    3 +++
 3 files changed, 38 insertions(+), 3 deletions(-)

Index: seabios/src/acpi.c
===================================================================
--- seabios.orig/src/acpi.c
+++ seabios/src/acpi.c
@@ -433,6 +433,18 @@ void acpi_bios_init(void)
     io_apic->interrupt = cpu_to_le32(0);
 
     struct madt_intsrcovr *intsrcovr = (void*)&io_apic[1];
+
+    if (irq0override) {
+        memset(intsrcovr, 0, sizeof(*intsrcovr));
+        intsrcovr->type   = APIC_XRUPT_OVERRIDE;
+        intsrcovr->length = sizeof(*intsrcovr);
+        intsrcovr->source = 0;
+        intsrcovr->gsi    = 2;
+        intsrcovr->flags  = 0; /* conforms to bus specifications */
+        intsrcovr++;
+        madt_size += sizeof(struct madt_intsrcovr);
+    }
+
     for (i = 0; i < 16; i++) {
         if (!(PCI_ISA_IRQ_MASK & (1 << i)))
             /* No need for a INT source override structure. */
Index: seabios/src/mptable.c
===================================================================
--- seabios.orig/src/mptable.c
+++ seabios/src/mptable.c
@@ -10,6 +10,12 @@
 #include "config.h" // CONFIG_*
 #include "mptable.h" // MPTABLE_SIGNATURE
 
+#if CONFIG_KVM
+int irq0override = 1;
+#else
+int irq0override = 0;
+#endif
+
 void
 mptable_init(void)
 {
@@ -29,7 +35,10 @@ mptable_init(void)
                   + sizeof(struct mpt_cpu) * smp_cpus
                   + sizeof(struct mpt_bus)
                   + sizeof(struct mpt_ioapic)
-                  + sizeof(struct mpt_intsrc) * 16);
+                  + sizeof(struct mpt_intsrc) * 15);
+    if (!irq0override)
+        length += sizeof(struct mpt_intsrc);
+
     if (start + length > bios_table_end_addr) {
         dprintf(1, "No room for MPTABLE!\n");
         return;
@@ -96,13 +105,24 @@ mptable_init(void)
 
     /* irqs */
     struct mpt_intsrc *intsrcs = (void *)&ioapic[1];
+    int j = 0;
     for(i = 0; i < 16; i++) {
-        struct mpt_intsrc *isrc = &intsrcs[i];
+        struct mpt_intsrc *isrc;
+        /* One entry per ioapic interrupt destination. Destination 2 is covered
+           by irq0->inti2 override (i == 0). Source IRQ 2 is unused */
+        if (irq0override && i == 2) {
+            j = 1;
+            continue;
+        }
+        isrc = &intsrcs[i - j];
         memset(isrc, 0, sizeof(*isrc));
         isrc->type = MPT_TYPE_INTSRC;
         isrc->srcbusirq = i;
         isrc->dstapic = ioapic_id;
-        isrc->dstirq = i;
+        if (irq0override && i == 0)
+	    isrc->dstirq = 2;
+        else
+	    isrc->dstirq = i;
     }
 
     // Set checksum.
Index: seabios/src/util.h
===================================================================
--- seabios.orig/src/util.h
+++ seabios/src/util.h
@@ -238,4 +238,7 @@ void reset_vector() __attribute__ ((nore
 // misc.c
 extern u8 BiosChecksum;
 
+// mptable.c
+extern int irq0override;
+
 #endif // util.h