[PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[Erich Mcmillan]

From: Erich McMillan <erich.mcmillan@hp.com>

At HPi we have a need for increased fw size to enable testing of our custom fw.

Signed-off-by: Erich McMillan <erich.mcmillan@hp.com>

Change since v4:
     Add explicit return to pc_machine_set_max_fw_size.
     Remove /* default */ from max_fw_size initialization.
---

 hw/i386/pc.c         | 52 ++++++++++++++++++++++++++++++++++++++++++++
 hw/i386/pc_sysfw.c   | 13 ++---------
 include/hw/i386/pc.h |  2 ++
 3 files changed, 56 insertions(+), 11 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index d11daacc23..6e66cbbc41 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1869,6 +1869,51 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
     pcms->max_ram_below_4g = value;
 }
 
+static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+    uint64_t value = pcms->max_fw_size;
+
+    visit_type_size(v, name, &value, errp);
+}
+
+static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+    Error *error = NULL;
+    uint64_t value;
+
+    visit_type_size(v, name, &value, &error);
+    if (error) {
+        error_propagate(errp, error);
+        return;
+    }
+
+    /*
+    * We don't have a theoretically justifiable exact lower bound on the base
+    * address of any flash mapping. In practice, the IO-APIC MMIO range is
+    * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
+    * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
+    * size.
+    */
+    if (value > 16 * MiB) {
+        error_setg(errp,
+                   "User specified max allowed firmware size %" PRIu64 " is "
+                   "greater than 16MiB. If combined firwmare size exceeds "
+                   "16MiB the system may not boot, or experience intermittent"
+                   "stability issues.",
+                   value);
+    }
+
+    pcms->max_fw_size = value;
+
+    return;
+}
+
 static void pc_machine_initfn(Object *obj)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
@@ -1884,6 +1929,7 @@ static void pc_machine_initfn(Object *obj)
     pcms->smbus_enabled = true;
     pcms->sata_enabled = true;
     pcms->pit_enabled = true;
+    pcms->max_fw_size = 8 * MiB;
 
     pc_system_flash_create(pcms);
     pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
@@ -2004,6 +2050,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
 
     object_class_property_add_bool(oc, PC_MACHINE_PIT,
         pc_machine_get_pit, pc_machine_set_pit);
+
+    object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
+        pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
+        NULL, NULL);
+    object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
+        "Maximum combined firmware size");
 }
 
 static const TypeInfo pc_machine_info = {
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index b6c0822fe3..22450ba0ef 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -39,15 +39,6 @@
 #include "hw/block/flash.h"
 #include "sysemu/kvm.h"
 
-/*
- * We don't have a theoretically justifiable exact lower bound on the base
- * address of any flash mapping. In practice, the IO-APIC MMIO range is
- * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
- * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
- * size.
- */
-#define FLASH_SIZE_LIMIT (8 * MiB)
-
 #define FLASH_SECTOR_SIZE 4096
 
 static void pc_isa_bios_init(MemoryRegion *rom_memory,
@@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
         }
         if ((hwaddr)size != size
             || total_size > HWADDR_MAX - size
-            || total_size + size > FLASH_SIZE_LIMIT) {
+            || total_size + size > pcms->max_fw_size) {
             error_report("combined size of system firmware exceeds "
                          "%" PRIu64 " bytes",
-                         FLASH_SIZE_LIMIT);
+                         pcms->max_fw_size);
             exit(1);
         }
 
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index fe52e165b2..f7c8e7cbfe 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -43,6 +43,7 @@ struct PCMachineState {
     bool smbus_enabled;
     bool sata_enabled;
     bool pit_enabled;
+    uint64_t max_fw_size;
 
     /* NUMA information: */
     uint64_t numa_nodes;
@@ -59,6 +60,7 @@ struct PCMachineState {
 #define PC_MACHINE_SMBUS            "smbus"
 #define PC_MACHINE_SATA             "sata"
 #define PC_MACHINE_PIT              "pit"
+#define PC_MACHINE_MAX_FW_SIZE      "max-fw-size"
 
 /**
  * PCMachineClass:
-- 
2.25.1

Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[Laszlo Ersek]

Hi Erich,

when processing review feedback, please pay attention to *where* the
review comments are inserted, in response to your patch email.

I'm pointing this out not because I want to annoy you with my
obsessions, but because I consider this discussion a kind of "git +
mailing lists" training for you. (In accordance with your first message
on the topic.)

Please see specifics below:

On 09/25/20 05:36, Erich Mcmillan wrote:
> From: Erich McMillan <erich.mcmillan@hp.com>
> 
> At HPi we have a need for increased fw size to enable testing of our custom fw.
> 
> Signed-off-by: Erich McMillan <erich.mcmillan@hp.com>
> 
> Change since v4:
>      Add explicit return to pc_machine_set_max_fw_size.
>      Remove /* default */ from max_fw_size initialization.
> ---
> 
>  hw/i386/pc.c         | 52 ++++++++++++++++++++++++++++++++++++++++++++
>  hw/i386/pc_sysfw.c   | 13 ++---------
>  include/hw/i386/pc.h |  2 ++
>  3 files changed, 56 insertions(+), 11 deletions(-)

Please refer to my earlier feedback, archived at the following location:

http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com

As I say in that message, the v(n)->v(n+1) changelog belongs 'between
the "---" separator and the diffstat'. In that message, I marked the
specific location with [*].

Basically the "---" separator terminates the commit message, and the
first "diff --git" line starts the code changes. What's between them is
thrown away, when the patch is applied. So in that throwaway area,
git-format-patch places the diffstat automatically (because it gives
reviewers a helpful overview of the patch, but is not useful for patch
application). And that's also the area where the v(n)->v(n+1) changelog
should be included. Traditionally, we place that log above the diffstat.

> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d11daacc23..6e66cbbc41 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1869,6 +1869,51 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
>      pcms->max_ram_below_4g = value;
>  }
>  
> +static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
> +                                       const char *name, void *opaque,
> +                                       Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +    uint64_t value = pcms->max_fw_size;
> +
> +    visit_type_size(v, name, &value, errp);
> +}
> +
> +static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
> +                                       const char *name, void *opaque,
> +                                       Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +    Error *error = NULL;
> +    uint64_t value;
> +
> +    visit_type_size(v, name, &value, &error);
> +    if (error) {
> +        error_propagate(errp, error);
> +        return;
> +    }
> +
> +    /*
> +    * We don't have a theoretically justifiable exact lower bound on the base
> +    * address of any flash mapping. In practice, the IO-APIC MMIO range is
> +    * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> +    * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> +    * size.
> +    */
> +    if (value > 16 * MiB) {
> +        error_setg(errp,
> +                   "User specified max allowed firmware size %" PRIu64 " is "
> +                   "greater than 16MiB. If combined firwmare size exceeds "
> +                   "16MiB the system may not boot, or experience intermittent"
> +                   "stability issues.",
> +                   value);
> +    }
> +
> +    pcms->max_fw_size = value;
> +
> +    return;
> +}

This return statement is useless. Please see my review at:

http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com

There I wrote, 'Please put a "return" statement here'. And, my request
was placed *exactly between* the error_setg() call and the closing brace.

The idea being that, if we take the (value > 16 * MiB) branch, then yes
we need to set the error, but we also need to abandon the rest of the
function. If "value" is invalid (out of bounds), then "pcms->max_fw_size
= value" is exactly the assignment that we do *not* want to reach.

> +
>  static void pc_machine_initfn(Object *obj)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> @@ -1884,6 +1929,7 @@ static void pc_machine_initfn(Object *obj)
>      pcms->smbus_enabled = true;
>      pcms->sata_enabled = true;
>      pcms->pit_enabled = true;
> +    pcms->max_fw_size = 8 * MiB;

Thank you for dropping the comment.

Summary:

- the changelog is helpful (thanks!), it's placement is not perfect yet
- the return statement should be moved so that it terminate the (value >
16 * MiB) branch.

Also, I think "HPi" (rather than "HP") in the commit message *could* be
a typo (I'm not sure).

Thanks,
Laszlo


>  
>      pc_system_flash_create(pcms);
>      pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
> @@ -2004,6 +2050,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>  
>      object_class_property_add_bool(oc, PC_MACHINE_PIT,
>          pc_machine_get_pit, pc_machine_set_pit);
> +
> +    object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
> +        pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
> +        NULL, NULL);
> +    object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
> +        "Maximum combined firmware size");
>  }
>  
>  static const TypeInfo pc_machine_info = {
> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> index b6c0822fe3..22450ba0ef 100644
> --- a/hw/i386/pc_sysfw.c
> +++ b/hw/i386/pc_sysfw.c
> @@ -39,15 +39,6 @@
>  #include "hw/block/flash.h"
>  #include "sysemu/kvm.h"
>  
> -/*
> - * We don't have a theoretically justifiable exact lower bound on the base
> - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> - * size.
> - */
> -#define FLASH_SIZE_LIMIT (8 * MiB)
> -
>  #define FLASH_SECTOR_SIZE 4096
>  
>  static void pc_isa_bios_init(MemoryRegion *rom_memory,
> @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
>          }
>          if ((hwaddr)size != size
>              || total_size > HWADDR_MAX - size
> -            || total_size + size > FLASH_SIZE_LIMIT) {
> +            || total_size + size > pcms->max_fw_size) {
>              error_report("combined size of system firmware exceeds "
>                           "%" PRIu64 " bytes",
> -                         FLASH_SIZE_LIMIT);
> +                         pcms->max_fw_size);
>              exit(1);
>          }
>  
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index fe52e165b2..f7c8e7cbfe 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -43,6 +43,7 @@ struct PCMachineState {
>      bool smbus_enabled;
>      bool sata_enabled;
>      bool pit_enabled;
> +    uint64_t max_fw_size;
>  
>      /* NUMA information: */
>      uint64_t numa_nodes;
> @@ -59,6 +60,7 @@ struct PCMachineState {
>  #define PC_MACHINE_SMBUS            "smbus"
>  #define PC_MACHINE_SATA             "sata"
>  #define PC_MACHINE_PIT              "pit"
> +#define PC_MACHINE_MAX_FW_SIZE      "max-fw-size"
>  
>  /**
>   * PCMachineClass:
> 

RE: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[McMillan, Erich]

[-- Attachment #1: Type: text/plain, Size: 7897 bytes --]

Hi Laszlo,

Thank you for the feedback, apologies that I missed the exact line references I was moving too fast.
I appreciate you taking the time to explain the nuances.

On an unrelated note, it seems that my patches are no longer appearing in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html is this because I need to cc qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org> rather than –to?

-Erich

From: Laszlo Ersek [mailto:lersek@redhat.com]
Sent: Friday, September 25, 2020 2:00 AM
To: McMillan, Erich <erich.mcmillan@hp.com>; qemu-devel@nongnu.org
Cc: dgilbert@redhat.com; mst@redhat.com; marcel.apfelbaum@gmail.com; imammedo@redhat.com; kraxel@redhat.com
Subject: Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

Hi Erich,

when processing review feedback, please pay attention to *where* the
review comments are inserted, in response to your patch email.

I'm pointing this out not because I want to annoy you with my
obsessions, but because I consider this discussion a kind of "git +
mailing lists" training for you. (In accordance with your first message
on the topic.)

Please see specifics below:

On 09/25/20 05:36, Erich Mcmillan wrote:
> From: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
>
> At HPi we have a need for increased fw size to enable testing of our custom fw.
>
> Signed-off-by: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
>
> Change since v4:
> Add explicit return to pc_machine_set_max_fw_size.
> Remove /* default */ from max_fw_size initialization.
> ---
>
> hw/i386/pc.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
> hw/i386/pc_sysfw.c | 13 ++---------
> include/hw/i386/pc.h | 2 ++
> 3 files changed, 56 insertions(+), 11 deletions(-)

Please refer to my earlier feedback, archived at the following location:

http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com<http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com>

As I say in that message, the v(n)->v(n+1) changelog belongs 'between
the "---" separator and the diffstat'. In that message, I marked the
specific location with [*].

Basically the "---" separator terminates the commit message, and the
first "diff --git" line starts the code changes. What's between them is
thrown away, when the patch is applied. So in that throwaway area,
git-format-patch places the diffstat automatically (because it gives
reviewers a helpful overview of the patch, but is not useful for patch
application). And that's also the area where the v(n)->v(n+1) changelog
should be included. Traditionally, we place that log above the diffstat.

>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d11daacc23..6e66cbbc41 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1869,6 +1869,51 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
> pcms->max_ram_below_4g = value;
> }
>
> +static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
> + const char *name, void *opaque,
> + Error **errp)
> +{
> + PCMachineState *pcms = PC_MACHINE(obj);
> + uint64_t value = pcms->max_fw_size;
> +
> + visit_type_size(v, name, &value, errp);
> +}
> +
> +static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
> + const char *name, void *opaque,
> + Error **errp)
> +{
> + PCMachineState *pcms = PC_MACHINE(obj);
> + Error *error = NULL;
> + uint64_t value;
> +
> + visit_type_size(v, name, &value, &error);
> + if (error) {
> + error_propagate(errp, error);
> + return;
> + }
> +
> + /*
> + * We don't have a theoretically justifiable exact lower bound on the base
> + * address of any flash mapping. In practice, the IO-APIC MMIO range is
> + * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> + * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> + * size.
> + */
> + if (value > 16 * MiB) {
> + error_setg(errp,
> + "User specified max allowed firmware size %" PRIu64 " is "
> + "greater than 16MiB. If combined firwmare size exceeds "
> + "16MiB the system may not boot, or experience intermittent"
> + "stability issues.",
> + value);
> + }
> +
> + pcms->max_fw_size = value;
> +
> + return;
> +}

This return statement is useless. Please see my review at:

http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com<http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com>

There I wrote, 'Please put a "return" statement here'. And, my request
was placed *exactly between* the error_setg() call and the closing brace.

The idea being that, if we take the (value > 16 * MiB) branch, then yes
we need to set the error, but we also need to abandon the rest of the
function. If "value" is invalid (out of bounds), then "pcms->max_fw_size
= value" is exactly the assignment that we do *not* want to reach.

> +
> static void pc_machine_initfn(Object *obj)
> {
> PCMachineState *pcms = PC_MACHINE(obj);
> @@ -1884,6 +1929,7 @@ static void pc_machine_initfn(Object *obj)
> pcms->smbus_enabled = true;
> pcms->sata_enabled = true;
> pcms->pit_enabled = true;
> + pcms->max_fw_size = 8 * MiB;

Thank you for dropping the comment.

Summary:

- the changelog is helpful (thanks!), it's placement is not perfect yet
- the return statement should be moved so that it terminate the (value >
16 * MiB) branch.

Also, I think "HPi" (rather than "HP") in the commit message *could* be
a typo (I'm not sure).

Thanks,
Laszlo


>
> pc_system_flash_create(pcms);
> pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
> @@ -2004,6 +2050,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>
> object_class_property_add_bool(oc, PC_MACHINE_PIT,
> pc_machine_get_pit, pc_machine_set_pit);
> +
> + object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
> + pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
> + NULL, NULL);
> + object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
> + "Maximum combined firmware size");
> }
>
> static const TypeInfo pc_machine_info = {
> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> index b6c0822fe3..22450ba0ef 100644
> --- a/hw/i386/pc_sysfw.c
> +++ b/hw/i386/pc_sysfw.c
> @@ -39,15 +39,6 @@
> #include "hw/block/flash.h"
> #include "sysemu/kvm.h"
>
> -/*
> - * We don't have a theoretically justifiable exact lower bound on the base
> - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> - * size.
> - */
> -#define FLASH_SIZE_LIMIT (8 * MiB)
> -
> #define FLASH_SECTOR_SIZE 4096
>
> static void pc_isa_bios_init(MemoryRegion *rom_memory,
> @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
> }
> if ((hwaddr)size != size
> || total_size > HWADDR_MAX - size
> - || total_size + size > FLASH_SIZE_LIMIT) {
> + || total_size + size > pcms->max_fw_size) {
> error_report("combined size of system firmware exceeds "
> "%" PRIu64 " bytes",
> - FLASH_SIZE_LIMIT);
> + pcms->max_fw_size);
> exit(1);
> }
>
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index fe52e165b2..f7c8e7cbfe 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -43,6 +43,7 @@ struct PCMachineState {
> bool smbus_enabled;
> bool sata_enabled;
> bool pit_enabled;
> + uint64_t max_fw_size;
>
> /* NUMA information: */
> uint64_t numa_nodes;
> @@ -59,6 +60,7 @@ struct PCMachineState {
> #define PC_MACHINE_SMBUS "smbus"
> #define PC_MACHINE_SATA "sata"
> #define PC_MACHINE_PIT "pit"
> +#define PC_MACHINE_MAX_FW_SIZE "max-fw-size"
>
> /**
> * PCMachineClass:
>

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RE: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[McMillan, Erich]

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Additionally HPi is not a mistake, corporate requires that we refer to ourselves as Hewlett Packard Inc since the split in 2015. I will perhaps update this to be the full name for clarity.


From: McMillan, Erich
Sent: Friday, September 25, 2020 12:15 PM
To: Laszlo Ersek <lersek@redhat.com>; qemu-devel@nongnu.org
Cc: dgilbert@redhat.com; mst@redhat.com; marcel.apfelbaum@gmail.com; imammedo@redhat.com; kraxel@redhat.com
Subject: RE: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

Hi Laszlo,

Thank you for the feedback, apologies that I missed the exact line references I was moving too fast.
I appreciate you taking the time to explain the nuances.

On an unrelated note, it seems that my patches are no longer appearing in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html is this because I need to cc qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org> rather than –to?

-Erich

From: Laszlo Ersek [mailto:lersek@redhat.com]
Sent: Friday, September 25, 2020 2:00 AM
To: McMillan, Erich <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>; qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org>
Cc: dgilbert@redhat.com<mailto:dgilbert@redhat.com>; mst@redhat.com<mailto:mst@redhat.com>; marcel.apfelbaum@gmail.com<mailto:marcel.apfelbaum@gmail.com>; imammedo@redhat.com<mailto:imammedo@redhat.com>; kraxel@redhat.com<mailto:kraxel@redhat.com>
Subject: Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

Hi Erich,

when processing review feedback, please pay attention to *where* the
review comments are inserted, in response to your patch email.

I'm pointing this out not because I want to annoy you with my
obsessions, but because I consider this discussion a kind of "git +
mailing lists" training for you. (In accordance with your first message
on the topic.)

Please see specifics below:

On 09/25/20 05:36, Erich Mcmillan wrote:
> From: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
>
> At HPi we have a need for increased fw size to enable testing of our custom fw.
>
> Signed-off-by: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
>
> Change since v4:
> Add explicit return to pc_machine_set_max_fw_size.
> Remove /* default */ from max_fw_size initialization.
> ---
>
> hw/i386/pc.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
> hw/i386/pc_sysfw.c | 13 ++---------
> include/hw/i386/pc.h | 2 ++
> 3 files changed, 56 insertions(+), 11 deletions(-)

Please refer to my earlier feedback, archived at the following location:

http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com<http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com>

As I say in that message, the v(n)->v(n+1) changelog belongs 'between
the "---" separator and the diffstat'. In that message, I marked the
specific location with [*].

Basically the "---" separator terminates the commit message, and the
first "diff --git" line starts the code changes. What's between them is
thrown away, when the patch is applied. So in that throwaway area,
git-format-patch places the diffstat automatically (because it gives
reviewers a helpful overview of the patch, but is not useful for patch
application). And that's also the area where the v(n)->v(n+1) changelog
should be included. Traditionally, we place that log above the diffstat.

>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d11daacc23..6e66cbbc41 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1869,6 +1869,51 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
> pcms->max_ram_below_4g = value;
> }
>
> +static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
> + const char *name, void *opaque,
> + Error **errp)
> +{
> + PCMachineState *pcms = PC_MACHINE(obj);
> + uint64_t value = pcms->max_fw_size;
> +
> + visit_type_size(v, name, &value, errp);
> +}
> +
> +static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
> + const char *name, void *opaque,
> + Error **errp)
> +{
> + PCMachineState *pcms = PC_MACHINE(obj);
> + Error *error = NULL;
> + uint64_t value;
> +
> + visit_type_size(v, name, &value, &error);
> + if (error) {
> + error_propagate(errp, error);
> + return;
> + }
> +
> + /*
> + * We don't have a theoretically justifiable exact lower bound on the base
> + * address of any flash mapping. In practice, the IO-APIC MMIO range is
> + * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> + * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> + * size.
> + */
> + if (value > 16 * MiB) {
> + error_setg(errp,
> + "User specified max allowed firmware size %" PRIu64 " is "
> + "greater than 16MiB. If combined firwmare size exceeds "
> + "16MiB the system may not boot, or experience intermittent"
> + "stability issues.",
> + value);
> + }
> +
> + pcms->max_fw_size = value;
> +
> + return;
> +}

This return statement is useless. Please see my review at:

http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com<http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com>

There I wrote, 'Please put a "return" statement here'. And, my request
was placed *exactly between* the error_setg() call and the closing brace.

The idea being that, if we take the (value > 16 * MiB) branch, then yes
we need to set the error, but we also need to abandon the rest of the
function. If "value" is invalid (out of bounds), then "pcms->max_fw_size
= value" is exactly the assignment that we do *not* want to reach.

> +
> static void pc_machine_initfn(Object *obj)
> {
> PCMachineState *pcms = PC_MACHINE(obj);
> @@ -1884,6 +1929,7 @@ static void pc_machine_initfn(Object *obj)
> pcms->smbus_enabled = true;
> pcms->sata_enabled = true;
> pcms->pit_enabled = true;
> + pcms->max_fw_size = 8 * MiB;

Thank you for dropping the comment.

Summary:

- the changelog is helpful (thanks!), it's placement is not perfect yet
- the return statement should be moved so that it terminate the (value >
16 * MiB) branch.

Also, I think "HPi" (rather than "HP") in the commit message *could* be
a typo (I'm not sure).

Thanks,
Laszlo


>
> pc_system_flash_create(pcms);
> pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
> @@ -2004,6 +2050,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>
> object_class_property_add_bool(oc, PC_MACHINE_PIT,
> pc_machine_get_pit, pc_machine_set_pit);
> +
> + object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
> + pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
> + NULL, NULL);
> + object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
> + "Maximum combined firmware size");
> }
>
> static const TypeInfo pc_machine_info = {
> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> index b6c0822fe3..22450ba0ef 100644
> --- a/hw/i386/pc_sysfw.c
> +++ b/hw/i386/pc_sysfw.c
> @@ -39,15 +39,6 @@
> #include "hw/block/flash.h"
> #include "sysemu/kvm.h"
>
> -/*
> - * We don't have a theoretically justifiable exact lower bound on the base
> - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> - * size.
> - */
> -#define FLASH_SIZE_LIMIT (8 * MiB)
> -
> #define FLASH_SECTOR_SIZE 4096
>
> static void pc_isa_bios_init(MemoryRegion *rom_memory,
> @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
> }
> if ((hwaddr)size != size
> || total_size > HWADDR_MAX - size
> - || total_size + size > FLASH_SIZE_LIMIT) {
> + || total_size + size > pcms->max_fw_size) {
> error_report("combined size of system firmware exceeds "
> "%" PRIu64 " bytes",
> - FLASH_SIZE_LIMIT);
> + pcms->max_fw_size);
> exit(1);
> }
>
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index fe52e165b2..f7c8e7cbfe 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -43,6 +43,7 @@ struct PCMachineState {
> bool smbus_enabled;
> bool sata_enabled;
> bool pit_enabled;
> + uint64_t max_fw_size;
>
> /* NUMA information: */
> uint64_t numa_nodes;
> @@ -59,6 +60,7 @@ struct PCMachineState {
> #define PC_MACHINE_SMBUS "smbus"
> #define PC_MACHINE_SATA "sata"
> #define PC_MACHINE_PIT "pit"
> +#define PC_MACHINE_MAX_FW_SIZE "max-fw-size"
>
> /**
> * PCMachineClass:
>

[-- Attachment #2: Type: text/html, Size: 15047 bytes --]

Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[Dr. David Alan Gilbert]

* McMillan, Erich (erich.mcmillan@hp.com) wrote:
> Additionally HPi is not a mistake, corporate requires that we refer to ourselves as Hewlett Packard Inc since the split in 2015. I will perhaps update this to be the full name for clarity.

Please note that no one outside of HP knows what HPi is; so you might
want to spell it out a bit.

Dave

> 
> From: McMillan, Erich
> Sent: Friday, September 25, 2020 12:15 PM
> To: Laszlo Ersek <lersek@redhat.com>; qemu-devel@nongnu.org
> Cc: dgilbert@redhat.com; mst@redhat.com; marcel.apfelbaum@gmail.com; imammedo@redhat.com; kraxel@redhat.com
> Subject: RE: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option
> 
> Hi Laszlo,
> 
> Thank you for the feedback, apologies that I missed the exact line references I was moving too fast.
> I appreciate you taking the time to explain the nuances.
> 
> On an unrelated note, it seems that my patches are no longer appearing in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html is this because I need to cc qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org> rather than –to?
> 
> -Erich
> 
> From: Laszlo Ersek [mailto:lersek@redhat.com]
> Sent: Friday, September 25, 2020 2:00 AM
> To: McMillan, Erich <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>; qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org>
> Cc: dgilbert@redhat.com<mailto:dgilbert@redhat.com>; mst@redhat.com<mailto:mst@redhat.com>; marcel.apfelbaum@gmail.com<mailto:marcel.apfelbaum@gmail.com>; imammedo@redhat.com<mailto:imammedo@redhat.com>; kraxel@redhat.com<mailto:kraxel@redhat.com>
> Subject: Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option
> 
> Hi Erich,
> 
> when processing review feedback, please pay attention to *where* the
> review comments are inserted, in response to your patch email.
> 
> I'm pointing this out not because I want to annoy you with my
> obsessions, but because I consider this discussion a kind of "git +
> mailing lists" training for you. (In accordance with your first message
> on the topic.)
> 
> Please see specifics below:
> 
> On 09/25/20 05:36, Erich Mcmillan wrote:
> > From: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
> >
> > At HPi we have a need for increased fw size to enable testing of our custom fw.
> >
> > Signed-off-by: Erich McMillan <erich.mcmillan@hp.com<mailto:erich.mcmillan@hp.com>>
> >
> > Change since v4:
> > Add explicit return to pc_machine_set_max_fw_size.
> > Remove /* default */ from max_fw_size initialization.
> > ---
> >
> > hw/i386/pc.c | 52 ++++++++++++++++++++++++++++++++++++++++++++
> > hw/i386/pc_sysfw.c | 13 ++---------
> > include/hw/i386/pc.h | 2 ++
> > 3 files changed, 56 insertions(+), 11 deletions(-)
> 
> Please refer to my earlier feedback, archived at the following location:
> 
> http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com<http://mid.mail-archive.com/8fdbf9f1-5125-1c39-4ec7-f99f017d4345@redhat.com>
> 
> As I say in that message, the v(n)->v(n+1) changelog belongs 'between
> the "---" separator and the diffstat'. In that message, I marked the
> specific location with [*].
> 
> Basically the "---" separator terminates the commit message, and the
> first "diff --git" line starts the code changes. What's between them is
> thrown away, when the patch is applied. So in that throwaway area,
> git-format-patch places the diffstat automatically (because it gives
> reviewers a helpful overview of the patch, but is not useful for patch
> application). And that's also the area where the v(n)->v(n+1) changelog
> should be included. Traditionally, we place that log above the diffstat.
> 
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index d11daacc23..6e66cbbc41 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1869,6 +1869,51 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
> > pcms->max_ram_below_4g = value;
> > }
> >
> > +static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
> > + const char *name, void *opaque,
> > + Error **errp)
> > +{
> > + PCMachineState *pcms = PC_MACHINE(obj);
> > + uint64_t value = pcms->max_fw_size;
> > +
> > + visit_type_size(v, name, &value, errp);
> > +}
> > +
> > +static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
> > + const char *name, void *opaque,
> > + Error **errp)
> > +{
> > + PCMachineState *pcms = PC_MACHINE(obj);
> > + Error *error = NULL;
> > + uint64_t value;
> > +
> > + visit_type_size(v, name, &value, &error);
> > + if (error) {
> > + error_propagate(errp, error);
> > + return;
> > + }
> > +
> > + /*
> > + * We don't have a theoretically justifiable exact lower bound on the base
> > + * address of any flash mapping. In practice, the IO-APIC MMIO range is
> > + * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> > + * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> > + * size.
> > + */
> > + if (value > 16 * MiB) {
> > + error_setg(errp,
> > + "User specified max allowed firmware size %" PRIu64 " is "
> > + "greater than 16MiB. If combined firwmare size exceeds "
> > + "16MiB the system may not boot, or experience intermittent"
> > + "stability issues.",
> > + value);
> > + }
> > +
> > + pcms->max_fw_size = value;
> > +
> > + return;
> > +}
> 
> This return statement is useless. Please see my review at:
> 
> http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com<http://mid.mail-archive.com/de343c71-f446-c68b-d0bc-5f9db97b5a00@redhat.com>
> 
> There I wrote, 'Please put a "return" statement here'. And, my request
> was placed *exactly between* the error_setg() call and the closing brace.
> 
> The idea being that, if we take the (value > 16 * MiB) branch, then yes
> we need to set the error, but we also need to abandon the rest of the
> function. If "value" is invalid (out of bounds), then "pcms->max_fw_size
> = value" is exactly the assignment that we do *not* want to reach.
> 
> > +
> > static void pc_machine_initfn(Object *obj)
> > {
> > PCMachineState *pcms = PC_MACHINE(obj);
> > @@ -1884,6 +1929,7 @@ static void pc_machine_initfn(Object *obj)
> > pcms->smbus_enabled = true;
> > pcms->sata_enabled = true;
> > pcms->pit_enabled = true;
> > + pcms->max_fw_size = 8 * MiB;
> 
> Thank you for dropping the comment.
> 
> Summary:
> 
> - the changelog is helpful (thanks!), it's placement is not perfect yet
> - the return statement should be moved so that it terminate the (value >
> 16 * MiB) branch.
> 
> Also, I think "HPi" (rather than "HP") in the commit message *could* be
> a typo (I'm not sure).
> 
> Thanks,
> Laszlo
> 
> 
> >
> > pc_system_flash_create(pcms);
> > pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
> > @@ -2004,6 +2050,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
> >
> > object_class_property_add_bool(oc, PC_MACHINE_PIT,
> > pc_machine_get_pit, pc_machine_set_pit);
> > +
> > + object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
> > + pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
> > + NULL, NULL);
> > + object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
> > + "Maximum combined firmware size");
> > }
> >
> > static const TypeInfo pc_machine_info = {
> > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> > index b6c0822fe3..22450ba0ef 100644
> > --- a/hw/i386/pc_sysfw.c
> > +++ b/hw/i386/pc_sysfw.c
> > @@ -39,15 +39,6 @@
> > #include "hw/block/flash.h"
> > #include "sysemu/kvm.h"
> >
> > -/*
> > - * We don't have a theoretically justifiable exact lower bound on the base
> > - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> > - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> > - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> > - * size.
> > - */
> > -#define FLASH_SIZE_LIMIT (8 * MiB)
> > -
> > #define FLASH_SECTOR_SIZE 4096
> >
> > static void pc_isa_bios_init(MemoryRegion *rom_memory,
> > @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
> > }
> > if ((hwaddr)size != size
> > || total_size > HWADDR_MAX - size
> > - || total_size + size > FLASH_SIZE_LIMIT) {
> > + || total_size + size > pcms->max_fw_size) {
> > error_report("combined size of system firmware exceeds "
> > "%" PRIu64 " bytes",
> > - FLASH_SIZE_LIMIT);
> > + pcms->max_fw_size);
> > exit(1);
> > }
> >
> > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > index fe52e165b2..f7c8e7cbfe 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -43,6 +43,7 @@ struct PCMachineState {
> > bool smbus_enabled;
> > bool sata_enabled;
> > bool pit_enabled;
> > + uint64_t max_fw_size;
> >
> > /* NUMA information: */
> > uint64_t numa_nodes;
> > @@ -59,6 +60,7 @@ struct PCMachineState {
> > #define PC_MACHINE_SMBUS "smbus"
> > #define PC_MACHINE_SATA "sata"
> > #define PC_MACHINE_PIT "pit"
> > +#define PC_MACHINE_MAX_FW_SIZE "max-fw-size"
> >
> > /**
> > * PCMachineClass:
> >
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[Philippe Mathieu-Daudé]

On 9/25/20 7:17 PM, McMillan, Erich wrote:
> Additionally HPi is not a mistake, corporate requires that we refer to
> ourselves as Hewlett Packard Inc since the split in 2015. I will perhaps
> update this to be the full name for clarity.

Maybe worth be explicit, else it is confusing (since your
email is hp.com and not hpi.com).

> 
>  
> 
>  
> 
> *From:*McMillan, Erich
> *Sent:* Friday, September 25, 2020 12:15 PM
> *To:* Laszlo Ersek <lersek@redhat.com>; qemu-devel@nongnu.org
> *Cc:* dgilbert@redhat.com; mst@redhat.com; marcel.apfelbaum@gmail.com;
> imammedo@redhat.com; kraxel@redhat.com
> *Subject:* RE: [PATCH v5] hw/i386/pc: add max combined fw size as
> machine configuration option
> 
>  
> 
> Hi Laszlo,
> 
>  
> 
> Thank you for the feedback, apologies that I missed the exact line
> references I was moving too fast.
> 
> I appreciate you taking the time to explain the nuances.
> 
>  
> 
> On an unrelated note, it seems that my patches are no longer appearing
> in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html
> is this because I need to cc qemu-devel@nongnu.org
> <mailto:qemu-devel@nongnu.org> rather than –to?

It is:
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09212.html

The archive is updated twice an hour I guess.

> 
>  
> 
> -Erich

Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[Laszlo Ersek]

On 09/25/20 19:14, McMillan, Erich wrote:

> On an unrelated note, it seems that my patches are no longer appearing in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html is this because I need to cc qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org> rather than –to?

Cc: and To: are equally fine. I can see both your v5 and v6 postings there:

https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09212.html
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09577.html

The qemu-devel list is very busy, plus <https://lists.nongnu.org/> hosts
a very large number of other lists -- so updates to the WebUI are done
in batches (I think once every 30 minutes, but I could be out of date on
that). A fresh posting almost never shows up immediately on the WebUI.
(I believe it may be delivered to subscribers via actual email more
quickly.)

Thanks
Laszlo

Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

[McMillan, Erich via]

[-- Attachment #1: Type: text/plain, Size: 1896 bytes --]

Laszlo,

Thanks double checking the archives. I did end up finding them the next day.

With regards to PATCH v6, I missed removing the squash commit message, so that will need to be fixed in v7 apologies for that.

-Erich
________________________________
From: Laszlo Ersek <lersek@redhat.com>
Sent: Monday, September 28, 2020 1:10 PM
To: McMillan, Erich <erich.mcmillan@hp.com>; qemu-devel@nongnu.org <qemu-devel@nongnu.org>
Cc: dgilbert@redhat.com <dgilbert@redhat.com>; mst@redhat.com <mst@redhat.com>; marcel.apfelbaum@gmail.com <marcel.apfelbaum@gmail.com>; imammedo@redhat.com <imammedo@redhat.com>; kraxel@redhat.com <kraxel@redhat.com>
Subject: Re: [PATCH v5] hw/i386/pc: add max combined fw size as machine configuration option

On 09/25/20 19:14, McMillan, Erich wrote:

> On an unrelated note, it seems that my patches are no longer appearing in https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html<https://lists.nongnu.org/archive/html/qemu-devel/2020-09/index.html> is this because I need to cc qemu-devel@nongnu.org<mailto:qemu-devel@nongnu.org> rather than –to?

Cc: and To: are equally fine. I can see both your v5 and v6 postings there:

https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09212.html<https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09212.html>
https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09577.html<https://lists.nongnu.org/archive/html/qemu-devel/2020-09/msg09577.html>

The qemu-devel list is very busy, plus <https://lists.nongnu.org/<https://lists.nongnu.org>> hosts
a very large number of other lists -- so updates to the WebUI are done
in batches (I think once every 30 minutes, but I could be out of date on
that). A fresh posting almost never shows up immediately on the WebUI.
(I believe it may be delivered to subscribers via actual email more
quickly.)

Thanks
Laszlo

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