[v2,09/13] hw/core/or-irq: Support more than 16 inputs to an OR gate

Message ID 20180604152941.20374-10-peter.maydell@linaro.org
State Superseded
Headers show
Series
  • iommu: support txattrs, support TCG execution, implement TZ MPC
Related show

Commit Message

Peter Maydell June 4, 2018, 3:29 p.m.
For the IoTKit MPC support, we need to wire together the
interrupt outputs of 17 MPCs; this exceeds the current
value of MAX_OR_LINES. Increase MAX_OR_LINES to 32 (which
should be enough for anyone).

The tricky part is retaining the migration compatibility for
existing OR gates; we add a subsection which is only used
for larger OR gates, and define it such that we can freely
increase MAX_OR_LINES in future (or even move to a dynamically
allocated levels[] array without an upper size limit) without
breaking compatibility.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

---
 include/hw/or-irq.h |  5 ++++-
 hw/core/or-irq.c    | 39 +++++++++++++++++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 3 deletions(-)

-- 
2.17.1

Comments

Alex Bennée June 14, 2018, 6:24 p.m. | #1
Peter Maydell <peter.maydell@linaro.org> writes:

> For the IoTKit MPC support, we need to wire together the

> interrupt outputs of 17 MPCs; this exceeds the current

> value of MAX_OR_LINES. Increase MAX_OR_LINES to 32 (which

> should be enough for anyone).

>

> The tricky part is retaining the migration compatibility for

> existing OR gates; we add a subsection which is only used

> for larger OR gates, and define it such that we can freely

> increase MAX_OR_LINES in future (or even move to a dynamically

> allocated levels[] array without an upper size limit) without

> breaking compatibility.

>

> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>


Reviewed-by: Alex Bennée <alex.bennee@linaro.org>


> ---

>  include/hw/or-irq.h |  5 ++++-

>  hw/core/or-irq.c    | 39 +++++++++++++++++++++++++++++++++++++--

>  2 files changed, 41 insertions(+), 3 deletions(-)

>

> diff --git a/include/hw/or-irq.h b/include/hw/or-irq.h

> index 3f6fc1b58a4..5a31e5a1881 100644

> --- a/include/hw/or-irq.h

> +++ b/include/hw/or-irq.h

> @@ -31,7 +31,10 @@

>

>  #define TYPE_OR_IRQ "or-irq"

>

> -#define MAX_OR_LINES      16

> +/* This can safely be increased if necessary without breaking

> + * migration compatibility (as long as it remains greater than 15).

> + */

> +#define MAX_OR_LINES      32

>

>  typedef struct OrIRQState qemu_or_irq;

>

> diff --git a/hw/core/or-irq.c b/hw/core/or-irq.c

> index f9d76c46415..a86901b673c 100644

> --- a/hw/core/or-irq.c

> +++ b/hw/core/or-irq.c

> @@ -66,14 +66,49 @@ static void or_irq_init(Object *obj)

>      qdev_init_gpio_out(DEVICE(obj), &s->out_irq, 1);

>  }

>

> +/* The original version of this device had a fixed 16 entries in its

> + * VMState array; devices with more inputs than this need to

> + * migrate the extra lines via a subsection.

> + * The subsection migrates as much of the levels[] array as is needed

> + * (including repeating the first 16 elements), to avoid the awkwardness

> + * of splitting it in two to meet the requirements of VMSTATE_VARRAY_UINT16.

> + */

> +#define OLD_MAX_OR_LINES 16

> +#if MAX_OR_LINES < OLD_MAX_OR_LINES

> +#error MAX_OR_LINES must be at least 16 for migration compatibility

> +#endif

> +

> +static bool vmstate_extras_needed(void *opaque)

> +{

> +    qemu_or_irq *s = OR_IRQ(opaque);

> +

> +    return s->num_lines >= OLD_MAX_OR_LINES;

> +}

> +

> +static const VMStateDescription vmstate_or_irq_extras = {

> +    .name = "or-irq-extras",

> +    .version_id = 1,

> +    .minimum_version_id = 1,

> +    .needed = vmstate_extras_needed,

> +    .fields = (VMStateField[]) {

> +        VMSTATE_VARRAY_UINT16_UNSAFE(levels, qemu_or_irq, num_lines, 0,

> +                                     vmstate_info_bool, bool),

> +        VMSTATE_END_OF_LIST(),

> +    },

> +};

> +

>  static const VMStateDescription vmstate_or_irq = {

>      .name = TYPE_OR_IRQ,

>      .version_id = 1,

>      .minimum_version_id = 1,

>      .fields = (VMStateField[]) {

> -        VMSTATE_BOOL_ARRAY(levels, qemu_or_irq, MAX_OR_LINES),

> +        VMSTATE_BOOL_SUB_ARRAY(levels, qemu_or_irq, 0, OLD_MAX_OR_LINES),

>          VMSTATE_END_OF_LIST(),

> -    }

> +    },

> +    .subsections = (const VMStateDescription*[]) {

> +        &vmstate_or_irq_extras,

> +        NULL

> +    },

>  };

>

>  static Property or_irq_properties[] = {



--
Alex Bennée

Patch

diff --git a/include/hw/or-irq.h b/include/hw/or-irq.h
index 3f6fc1b58a4..5a31e5a1881 100644
--- a/include/hw/or-irq.h
+++ b/include/hw/or-irq.h
@@ -31,7 +31,10 @@ 
 
 #define TYPE_OR_IRQ "or-irq"
 
-#define MAX_OR_LINES      16
+/* This can safely be increased if necessary without breaking
+ * migration compatibility (as long as it remains greater than 15).
+ */
+#define MAX_OR_LINES      32
 
 typedef struct OrIRQState qemu_or_irq;
 
diff --git a/hw/core/or-irq.c b/hw/core/or-irq.c
index f9d76c46415..a86901b673c 100644
--- a/hw/core/or-irq.c
+++ b/hw/core/or-irq.c
@@ -66,14 +66,49 @@  static void or_irq_init(Object *obj)
     qdev_init_gpio_out(DEVICE(obj), &s->out_irq, 1);
 }
 
+/* The original version of this device had a fixed 16 entries in its
+ * VMState array; devices with more inputs than this need to
+ * migrate the extra lines via a subsection.
+ * The subsection migrates as much of the levels[] array as is needed
+ * (including repeating the first 16 elements), to avoid the awkwardness
+ * of splitting it in two to meet the requirements of VMSTATE_VARRAY_UINT16.
+ */
+#define OLD_MAX_OR_LINES 16
+#if MAX_OR_LINES < OLD_MAX_OR_LINES
+#error MAX_OR_LINES must be at least 16 for migration compatibility
+#endif
+
+static bool vmstate_extras_needed(void *opaque)
+{
+    qemu_or_irq *s = OR_IRQ(opaque);
+
+    return s->num_lines >= OLD_MAX_OR_LINES;
+}
+
+static const VMStateDescription vmstate_or_irq_extras = {
+    .name = "or-irq-extras",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = vmstate_extras_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_VARRAY_UINT16_UNSAFE(levels, qemu_or_irq, num_lines, 0,
+                                     vmstate_info_bool, bool),
+        VMSTATE_END_OF_LIST(),
+    },
+};
+
 static const VMStateDescription vmstate_or_irq = {
     .name = TYPE_OR_IRQ,
     .version_id = 1,
     .minimum_version_id = 1,
     .fields = (VMStateField[]) {
-        VMSTATE_BOOL_ARRAY(levels, qemu_or_irq, MAX_OR_LINES),
+        VMSTATE_BOOL_SUB_ARRAY(levels, qemu_or_irq, 0, OLD_MAX_OR_LINES),
         VMSTATE_END_OF_LIST(),
-    }
+    },
+    .subsections = (const VMStateDescription*[]) {
+        &vmstate_or_irq_extras,
+        NULL
+    },
 };
 
 static Property or_irq_properties[] = {