Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Julien Grall]

On 13/06/17 12:44, Manish Jaggi wrote:

On 6/13/2017 4:58 PM, Julien Grall wrote:

On 13/06/17 12:02, Manish Jaggi wrote:

Will the below code be ok?


If you noticed, I didn't say this code is wrong. Instead I asked why
you use the same ID. Meaning, is there anything in the DSDT requiring
this value?


+ int tras_id = 0;


unsigned.


+ list_for_each_entry(its_data, _its_list, entry)
+ {
+gic_its->translation_id = ++trans_id;


You start the translation ID at 1. Why?


as per the ACPI spec the value should be unique to each GIC ITS unit.
Does starting with 1 break anything? Or should I start with a magic
number?


Rather than arguing on the start value here, you should have first
answer to the question regarding the usage of translation_id.

in v1 I assumed that it would be the same as read from host its tables,
so it would have a unique value as programmed by host firmware.


I understand that nobody is using it today. However, when I asked
around me nobody ruled out to any future usage of GIC ITS ID and
request this to be kept as it is.

This means that you can simply copy over the ACPI tables. Rather
regenerating them.


I dont follow your comment, a bit confused
In v1 you mentioned that "Please explain why you need to have the same
ID as the host."
now when you say we copy over the translation_id would be same as that
of host?


Usually when I say: "Please explain..." it means I want more 
documentation in the code because I am not sure to follow why it is 
necessary. It does not mean "The code is wrong". If it was, I would have 
clearly wrote it and give justification on it.


Furthermore, this kind of documentation will help a reader to understand 
your code and avoid spending hours to find a justification.


The contributor should be able to justify any code he wrote and help the 
reviewers to understand the patch quickly.


Cheers,

--
Julien Grall

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Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Manish Jaggi]

On 6/13/2017 4:58 PM, Julien Grall wrote:

On 13/06/17 12:02, Manish Jaggi wrote:

Will the below code be ok?


If you noticed, I didn't say this code is wrong. Instead I asked why
you use the same ID. Meaning, is there anything in the DSDT requiring
this value?


+ int tras_id = 0;


unsigned.


+ list_for_each_entry(its_data, _its_list, entry)
+ {
+gic_its->translation_id = ++trans_id;


You start the translation ID at 1. Why?


as per the ACPI spec the value should be unique to each GIC ITS unit.
Does starting with 1 break anything? Or should I start with a magic 
number?


Rather than arguing on the start value here, you should have first 
answer to the question regarding the usage of translation_id.
in v1 I assumed that it would be the same as read from host its tables, 
so it would have a unique value as programmed by host firmware.


I understand that nobody is using it today. However, when I asked 
around me nobody ruled out to any future usage of GIC ITS ID and 
request this to be kept as it is.


This means that you can simply copy over the ACPI tables. Rather 
regenerating them.



I dont follow your comment, a bit confused
In v1 you mentioned that "Please explain why you need to have the same 
ID as the host."
now when you say we copy over the translation_id would be same as that 
of host?



Cheers,




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Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Julien Grall]

On 13/06/17 12:02, Manish Jaggi wrote:

Will the below code be ok?


If you noticed, I didn't say this code is wrong. Instead I asked why
you use the same ID. Meaning, is there anything in the DSDT requiring
this value?


+ int tras_id = 0;


unsigned.


+ list_for_each_entry(its_data, _its_list, entry)
+ {
+gic_its->translation_id = ++trans_id;


You start the translation ID at 1. Why?


as per the ACPI spec the value should be unique to each GIC ITS unit.
Does starting with 1 break anything? Or should I start with a magic number?


Rather than arguing on the start value here, you should have first 
answer to the question regarding the usage of translation_id.


I understand that nobody is using it today. However, when I asked around 
me nobody ruled out to any future usage of GIC ITS ID and request this 
to be kept as it is.


This means that you can simply copy over the ACPI tables. Rather 
regenerating them.


Cheers,

--
Julien Grall

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Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Manish Jaggi]

Hi julien,

On 6/9/2017 2:09 PM, Julien Grall wrote:



On 09/06/2017 07:48, Manish Jaggi wrote:


On 6/8/2017 7:28 PM, Julien Grall wrote:

Hi,

Hello Julien,


Hello,


+list_for_each_entry(its_data, _its_list, entry)
+{


Pointless {


+size += sizeof(struct acpi_madt_generic_translator);
+}

Just for readability of code.


You have indentation for that. So I don't think it helps.

ok i will fix it.




Same here + add a newline.


Sure.

+return size;
+}
+
+u32 gicv3_its_make_hwdom_madt(u8 *base_ptr, u32 offset)
+{
+struct acpi_madt_generic_translator *gic_its;
+const struct host_its *its_data;
+u32 table_len = offset, size;
+
+/* Update GIC ITS information in hardware domain's MADT */
+list_for_each_entry(its_data, _its_list, entry)
+{
+size = sizeof(struct acpi_madt_generic_translator);
+gic_its = (struct acpi_madt_generic_translator *)(base_ptr +
table_len);


This line is likely too long.


I will check it.

+gic_its->header.type = ACPI_MADT_TYPE_GENERIC_TRANSLATOR;
+gic_its->header.length = size;
+gic_its->base_address = its_data->addr;


On the previous patch you had:

gic_its->translation_id = its_data->translation_id;

I asked to explain why you need to have the same ID as the host. And
now you dropped it. This does not match the spec (Table 5-67 in ACPI
6.1):

"GIC ITS ID. In a system with multiple GIC ITS units, this value must
be unique to each one."

But here, the ITS ID will not be unique. So why did you dropped it?


The reason I dropped it from its_data as I was not setting it. So it
doesn't belong there.


Where would it belong then?

This function is used to generate ACPI tables for the hardware domain.



Will the below code be ok?


If you noticed, I didn't say this code is wrong. Instead I asked why 
you use the same ID. Meaning, is there anything in the DSDT requiring 
this value?



+ int tras_id = 0;


unsigned.


+ list_for_each_entry(its_data, _its_list, entry)
+ {
+gic_its->translation_id = ++trans_id;


You start the translation ID at 1. Why?


as per the ACPI spec the value should be unique to each GIC ITS unit.
Does starting with 1 break anything? Or should I start with a magic number?



+table_len +=  size;
+}
+return table_len;
+}
+
 /*
  * Create the respective guest DT nodes from a list of host ITSes.
  * This copies the reg property, so the guest sees the ITS at the 
same

address
@@ -992,6 +1045,26 @@ int gicv3_its_make_hwdom_dt_nodes(const struct
domain *d,
 return res;
 }

+int gicv3_its_acpi_init(struct acpi_subtable_header *header, const
unsigned long end)


ACPI is an option and is not able by default. Please make sure that
this code build without ACPI. Likely this means surrounding with
#ifdef CONFIG_ACPI.

I will get compiled but not called. Do you still want to put ifdef, i
can add that.


All ACPIs functions are protected by ifdef. So this one should be as 
well.

ok will do.





+{
+struct acpi_madt_generic_translator *its_entry;
+struct host_its *its_data;
+
+its_data = xzalloc(struct host_its);
+if (!its_data)


Coding style.


Sure.

+return -1;
+
+its_entry = (struct acpi_madt_generic_translator *)header;
+its_data->addr  = its_entry->base_address;
+its_data->size = ACPI_GICV3_ITS_MEM_SIZE;
+
+spin_lock_init(_data->cmd_lock);
+
+printk("GICv3: Found ITS @0x%lx\n", its_data->addr);
+
+list_add_tail(_data->entry, _its_list);


As said on v1, likely you could re-use factorize a part of
gicv3_its_dt_init to avoid implementing twice the initialization.


For this I have a different opinion.


Why didn't you state it on the previous version? I usually interpret a 
non-answer as an acknowledgment.



gicv3_its_dt_init has a loop dt_for_each_child_node(node, its) while
gicv3_its_acpi_init is a callback.
Moreover,  apart from xzalloc and list_add_tail most of the code is
different. so IMHO keeping them separate is better.


You still set addr and size as in the DT counterpart. Also, this is a 
call to forget to initialize a field if we decided to extend the 
structure host_its. So I still don't see any reason to open-code it 
and take the risk to introduce bug in the future...

ok Added.



Also newline.


+return 0;
+}


Newline here.

Sure.


 /* Scan the DT for any ITS nodes and create a list of host ITSes 
out of

it. */
 void gicv3_its_dt_init(const struct dt_device_node *node)
 {
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index c927306..f0f6d12 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -1333,9 +1333,8 @@ static int gicv3_iomem_deny_access(const struct
domain *d)
 return iomem_deny_access(d, mfn, mfn + nr);
 }

-return 0;
+return gicv3_its_deny_access(d);


Copying my answer from v1 for convenience:

if ( vbase != INVALID_PADDR )
{
mfn = vbase >> PAGE_SHIFT;
nr = DIV_ROUND_UP(csize, PAGE_SIZE);
return 

Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Julien Grall]

On 09/06/2017 07:48, Manish Jaggi wrote:


On 6/8/2017 7:28 PM, Julien Grall wrote:

Hi,

Hello Julien,


Hello,


+list_for_each_entry(its_data, _its_list, entry)
+{


Pointless {


+size += sizeof(struct acpi_madt_generic_translator);
+}

Just for readability of code.


You have indentation for that. So I don't think it helps.



Same here + add a newline.


Sure.

+return size;
+}
+
+u32 gicv3_its_make_hwdom_madt(u8 *base_ptr, u32 offset)
+{
+struct acpi_madt_generic_translator *gic_its;
+const struct host_its *its_data;
+u32 table_len = offset, size;
+
+/* Update GIC ITS information in hardware domain's MADT */
+list_for_each_entry(its_data, _its_list, entry)
+{
+size = sizeof(struct acpi_madt_generic_translator);
+gic_its = (struct acpi_madt_generic_translator *)(base_ptr +
table_len);


This line is likely too long.


I will check it.

+gic_its->header.type = ACPI_MADT_TYPE_GENERIC_TRANSLATOR;
+gic_its->header.length = size;
+gic_its->base_address = its_data->addr;


On the previous patch you had:

gic_its->translation_id = its_data->translation_id;

I asked to explain why you need to have the same ID as the host. And
now you dropped it. This does not match the spec (Table 5-67 in ACPI
6.1):

"GIC ITS ID. In a system with multiple GIC ITS units, this value must
be unique to each one."

But here, the ITS ID will not be unique. So why did you dropped it?


The reason I dropped it from its_data as I was not setting it. So it
doesn't belong there.


Where would it belong then?

This function is used to generate ACPI tables for the hardware domain.



Will the below code be ok?


If you noticed, I didn't say this code is wrong. Instead I asked why you 
use the same ID. Meaning, is there anything in the DSDT requiring this 
value?



+ int tras_id = 0;


unsigned.


+ list_for_each_entry(its_data, _its_list, entry)
+ {
+gic_its->translation_id = ++trans_id;


You start the translation ID at 1. Why?




+table_len +=  size;
+}
+return table_len;
+}
+
 /*
  * Create the respective guest DT nodes from a list of host ITSes.
  * This copies the reg property, so the guest sees the ITS at the same
address
@@ -992,6 +1045,26 @@ int gicv3_its_make_hwdom_dt_nodes(const struct
domain *d,
 return res;
 }

+int gicv3_its_acpi_init(struct acpi_subtable_header *header, const
unsigned long end)


ACPI is an option and is not able by default. Please make sure that
this code build without ACPI. Likely this means surrounding with
#ifdef CONFIG_ACPI.

I will get compiled but not called. Do you still want to put ifdef, i
can add that.


All ACPIs functions are protected by ifdef. So this one should be as well.




+{
+struct acpi_madt_generic_translator *its_entry;
+struct host_its *its_data;
+
+its_data = xzalloc(struct host_its);
+if (!its_data)


Coding style.


Sure.

+return -1;
+
+its_entry = (struct acpi_madt_generic_translator *)header;
+its_data->addr  = its_entry->base_address;
+its_data->size = ACPI_GICV3_ITS_MEM_SIZE;
+
+spin_lock_init(_data->cmd_lock);
+
+printk("GICv3: Found ITS @0x%lx\n", its_data->addr);
+
+list_add_tail(_data->entry, _its_list);


As said on v1, likely you could re-use factorize a part of
gicv3_its_dt_init to avoid implementing twice the initialization.


For this I have a different opinion.


Why didn't you state it on the previous version? I usually interpret a 
non-answer as an acknowledgment.



gicv3_its_dt_init has a loop  dt_for_each_child_node(node, its) while
gicv3_its_acpi_init is a callback.
Moreover,  apart from xzalloc and list_add_tail most of the code is
different. so IMHO keeping them separate is better.


You still set addr and size as in the DT counterpart. Also, this is a 
call to forget to initialize a field if we decided to extend the 
structure host_its. So I still don't see any reason to open-code it and 
take the risk to introduce bug in the future...



Also newline.


+return 0;
+}


Newline here.

Sure.



 /* Scan the DT for any ITS nodes and create a list of host ITSes out of
it. */
 void gicv3_its_dt_init(const struct dt_device_node *node)
 {
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index c927306..f0f6d12 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -1333,9 +1333,8 @@ static int gicv3_iomem_deny_access(const struct
domain *d)
 return iomem_deny_access(d, mfn, mfn + nr);
 }

-return 0;
+return gicv3_its_deny_access(d);


Copying my answer from v1 for convenience:

if ( vbase != INVALID_PADDR )
{
mfn = vbase >> PAGE_SHIFT;
nr = DIV_ROUND_UP(csize, PAGE_SIZE);
return iomem_deny_access(d, mfn, mfn + nr);
}

When GICv3 is able to support GICv2, vbase will be valid and the code
will bail out after denying access to the GICV. So the ITS regions
will not be denied.


Ok, got your point. Would the below code be ok?

Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Manish Jaggi]

On 6/8/2017 7:28 PM, Julien Grall wrote:

Hi,

Hello Julien,


Please CC all relevant maintainers.

Sure. Will do in the next patch rev.


On 08/06/17 14:03, Manish Jaggi wrote:




Spurious newline


This patch supports ITS in hardware domain, supports ITS in Xen
when booting with ACPI.

Signed-off-by: Manish Jaggi 
---
Changes since v1:
- Moved its specific code to gic-v3-its.c
- fixed macros


It sounds like you haven't addressed all my comments. I will repeat 
them for this time. But next time, I will not bother reviewing your 
patch.

*Thanks* for reviewing the patch, I will try to address _all_ the comments




 xen/arch/arm/domain_build.c  |  6 ++--
 xen/arch/arm/gic-v3-its.c| 75
+++-
 xen/arch/arm/gic-v3.c| 10 --
 xen/include/asm-arm/gic_v3_its.h |  6 
 4 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 3abacc0..d6d6c94 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -20,7 +20,7 @@
 #include 
 #include 
 #include 
-


Why did you drop this newline?

I will fix it.



+#include 


Nack. I asked on v1 to separate code between GICv3 and ITS, it is not 
for directly calling gicv3 code directly in the common code.


If you need to call GICv3 specific code, then introduce a callback in 
gic_hw_operations.



Good point, I will add it.

 #include 
 #include 
 #include 
@@ -1804,7 +1804,9 @@ static int estimate_acpi_efi_size(struct domain
*d, struct kernel_info *kinfo)

 madt_size = sizeof(struct acpi_table_madt)
 + sizeof(struct acpi_madt_generic_interrupt) *
d->max_vcpus
-+ sizeof(struct acpi_madt_generic_distributor);
++ sizeof(struct acpi_madt_generic_distributor)
++ gicv3_its_madt_generic_translator_size();


See my comment above.

Will address it.



+
 if ( d->arch.vgic.version == GIC_V3 )
 madt_size += sizeof(struct acpi_madt_generic_redistributor)
  * d->arch.vgic.nr_regions;
diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 1fb06ca..937b970 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -25,14 +25,18 @@
 #include 
 #include 
 #include 
+#include 


The include are ordered alphabetically, please respect it.


Sure. I will fix it.

 #include 
 #include 
 #include 
 #include 
 #include 
+#include 
+#include 
+#include 


Ditto.


Sure. I will fix it.


 #define ITS_CMD_QUEUE_SZSZ_1M
-


Again, we don't drop newline for no reason.

I will fix it.



+#define ACPI_GICV3_ITS_MEM_SIZE (SZ_64K)
 /*
  * No lock here, as this list gets only populated upon boot while 
scanning
  * firmware tables for all host ITSes, and only gets iterated 
afterwards.

@@ -920,6 +924,55 @@ int gicv3_lpi_change_vcpu(struct domain *d, paddr_t
vdoorbell,
 return 0;
 }

+int gicv3_its_deny_access(const struct domain *d)
+{
+int rc = 0;
+unsigned long mfn, nr;
+const struct host_its *its_data;
+
+list_for_each_entry(its_data, _its_list, entry)
+{
+mfn = paddr_to_pfn(its_data->addr);
+nr = PFN_UP(ACPI_GICV3_ITS_MEM_SIZE);
+rc = iomem_deny_access(d, mfn, mfn + nr);
+if ( rc )
+goto end;


Hmmm, why not using a break here rather than a goto?

I can use break, np.



+}
+end:
+return rc;
+}
+
+u32 gicv3_its_madt_generic_translator_size(void)
+{
+const struct host_its *its_data;
+u32 size = 0;
+
+list_for_each_entry(its_data, _its_list, entry)
+{


Pointless {


+size += sizeof(struct acpi_madt_generic_translator);
+}

Just for readability of code.


Same here + add a newline.


Sure.

+return size;
+}
+
+u32 gicv3_its_make_hwdom_madt(u8 *base_ptr, u32 offset)
+{
+struct acpi_madt_generic_translator *gic_its;
+const struct host_its *its_data;
+u32 table_len = offset, size;
+
+/* Update GIC ITS information in hardware domain's MADT */
+list_for_each_entry(its_data, _its_list, entry)
+{
+size = sizeof(struct acpi_madt_generic_translator);
+gic_its = (struct acpi_madt_generic_translator *)(base_ptr +
table_len);


This line is likely too long.


I will check it.

+gic_its->header.type = ACPI_MADT_TYPE_GENERIC_TRANSLATOR;
+gic_its->header.length = size;
+gic_its->base_address = its_data->addr;


On the previous patch you had:

gic_its->translation_id = its_data->translation_id;

I asked to explain why you need to have the same ID as the host. And 
now you dropped it. This does not match the spec (Table 5-67 in ACPI 
6.1):


"GIC ITS ID. In a system with multiple GIC ITS units, this value must
be unique to each one."

But here, the ITS ID will not be unique. So why did you dropped it?

The reason I dropped it from its_data as I was not setting it. So it 
doesn't belong there.

Will the below code be ok?
+ int 

Re: [Xen-devel] [RFC v2][PATCH] arm-acpi: Add ITS Support for Dom0

[Julien Grall]

Hi,

Please CC all relevant maintainers.

On 08/06/17 14:03, Manish Jaggi wrote:




Spurious newline


This patch supports ITS in hardware domain, supports ITS in Xen
when booting with ACPI.

Signed-off-by: Manish Jaggi 
---
Changes since v1:
- Moved its specific code to gic-v3-its.c
- fixed macros


It sounds like you haven't addressed all my comments. I will repeat them 
for this time. But next time, I will not bother reviewing your patch.




 xen/arch/arm/domain_build.c  |  6 ++--
 xen/arch/arm/gic-v3-its.c| 75
+++-
 xen/arch/arm/gic-v3.c| 10 --
 xen/include/asm-arm/gic_v3_its.h |  6 
 4 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 3abacc0..d6d6c94 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -20,7 +20,7 @@
 #include 
 #include 
 #include 
-


Why did you drop this newline?


+#include 


Nack. I asked on v1 to separate code between GICv3 and ITS, it is not 
for directly calling gicv3 code directly in the common code.


If you need to call GICv3 specific code, then introduce a callback in 
gic_hw_operations.



 #include 
 #include 
 #include 
@@ -1804,7 +1804,9 @@ static int estimate_acpi_efi_size(struct domain
*d, struct kernel_info *kinfo)

 madt_size = sizeof(struct acpi_table_madt)
 + sizeof(struct acpi_madt_generic_interrupt) *
d->max_vcpus
-+ sizeof(struct acpi_madt_generic_distributor);
++ sizeof(struct acpi_madt_generic_distributor)
++ gicv3_its_madt_generic_translator_size();


See my comment above.


+
 if ( d->arch.vgic.version == GIC_V3 )
 madt_size += sizeof(struct acpi_madt_generic_redistributor)
  * d->arch.vgic.nr_regions;
diff --git a/xen/arch/arm/gic-v3-its.c b/xen/arch/arm/gic-v3-its.c
index 1fb06ca..937b970 100644
--- a/xen/arch/arm/gic-v3-its.c
+++ b/xen/arch/arm/gic-v3-its.c
@@ -25,14 +25,18 @@
 #include 
 #include 
 #include 
+#include 


The include are ordered alphabetically, please respect it.


 #include 
 #include 
 #include 
 #include 
 #include 
+#include 
+#include 
+#include 


Ditto.



 #define ITS_CMD_QUEUE_SZSZ_1M
-


Again, we don't drop newline for no reason.


+#define ACPI_GICV3_ITS_MEM_SIZE (SZ_64K)
 /*
  * No lock here, as this list gets only populated upon boot while scanning
  * firmware tables for all host ITSes, and only gets iterated afterwards.
@@ -920,6 +924,55 @@ int gicv3_lpi_change_vcpu(struct domain *d, paddr_t
vdoorbell,
 return 0;
 }

+int gicv3_its_deny_access(const struct domain *d)
+{
+int rc = 0;
+unsigned long mfn, nr;
+const struct host_its *its_data;
+
+list_for_each_entry(its_data, _its_list, entry)
+{
+mfn = paddr_to_pfn(its_data->addr);
+nr = PFN_UP(ACPI_GICV3_ITS_MEM_SIZE);
+rc = iomem_deny_access(d, mfn, mfn + nr);
+if ( rc )
+goto end;


Hmmm, why not using a break here rather than a goto?


+}
+end:
+return rc;
+}
+
+u32 gicv3_its_madt_generic_translator_size(void)
+{
+const struct host_its *its_data;
+u32 size = 0;
+
+list_for_each_entry(its_data, _its_list, entry)
+{


Pointless {


+size += sizeof(struct acpi_madt_generic_translator);
+}


Same here + add a newline.


+return size;
+}
+
+u32 gicv3_its_make_hwdom_madt(u8 *base_ptr, u32 offset)
+{
+struct acpi_madt_generic_translator *gic_its;
+const struct host_its *its_data;
+u32 table_len = offset, size;
+
+/* Update GIC ITS information in hardware domain's MADT */
+list_for_each_entry(its_data, _its_list, entry)
+{
+size = sizeof(struct acpi_madt_generic_translator);
+gic_its = (struct acpi_madt_generic_translator *)(base_ptr +
table_len);


This line is likely too long.


+gic_its->header.type = ACPI_MADT_TYPE_GENERIC_TRANSLATOR;
+gic_its->header.length = size;
+gic_its->base_address = its_data->addr;


On the previous patch you had:

gic_its->translation_id = its_data->translation_id;

I asked to explain why you need to have the same ID as the host. And now 
you dropped it. This does not match the spec (Table 5-67 in ACPI 6.1):


"GIC ITS ID. In a system with multiple GIC ITS units, this value must
be unique to each one."

But here, the ITS ID will not be unique. So why did you dropped it?


+table_len +=  size;
+}
+return table_len;
+}
+
 /*
  * Create the respective guest DT nodes from a list of host ITSes.
  * This copies the reg property, so the guest sees the ITS at the same
address
@@ -992,6 +1045,26 @@ int gicv3_its_make_hwdom_dt_nodes(const struct
domain *d,
 return res;
 }

+int gicv3_its_acpi_init(struct acpi_subtable_header *header, const
unsigned long end)


ACPI is an option and is not able by default. Please make sure that this 
code build without ACPI. Likely