[v6] irqchip/gic-v3: Enable non-coherent GIC designs probing

[PATCH v6 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by Lorenzo Pieralisi 11 months, 1 week ago

The GIC architecture specification defines a set of registers for
redistributors and ITSes that control the sharebility and cacheability
attributes of redistributors/ITSes initiator ports on the interconnect
(GICR_[V]PROPBASER, GICR_[V]PENDBASER, GITS_BASER<n>).

Architecturally the GIC provides a means to drive shareability and
cacheability attributes signals but it is not mandatory for designs to
wire up the corresponding interconnect signals that control the
cacheability/shareability of transactions.

Redistributors and ITSes interconnect ports can be connected to
non-coherent interconnects that are not able to manage the
shareability/cacheability attributes; this implicitly makes the
redistributors and ITSes non-coherent observers.

To enable non-coherent GIC designs on ACPI based systems, parse the MADT
GICC/GICR/ITS subtables non-coherent flags to determine whether the
respective components are non-coherent observers and force the
shareability attributes to be programmed into the redistributors and
ITSes registers.

An ACPI global function (acpi_get_madt_revision()) is added to retrieve
the MADT revision, in that it is essential to check the MADT revision
before checking for flags that were added with MADT revision 7 so that
if the kernel is booted with an ACPI MADT table with revision < 7 it
skips parsing the newly added flags (that should be zeroed reserved
values for MADT versions < 7 but they could turn out to be buggy and
should be ignored).

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
---
 drivers/acpi/processor_core.c    | 15 +++++++++++++++
 drivers/irqchip/irq-gic-v3-its.c |  4 ++++
 drivers/irqchip/irq-gic-v3.c     |  9 +++++++++
 include/linux/acpi.h             |  3 +++
 4 files changed, 31 insertions(+)

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index b203cfe28550..915713c0e9b7 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
 	return rv;
 }
 
+int __init acpi_get_madt_revision(void)
+{
+	struct acpi_table_header *madt = NULL;
+	int revision;
+
+	if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0, &madt)))
+		return -EINVAL;
+
+	revision = madt->revision;
+
+	acpi_put_table(madt);
+
+	return revision;
+}
+
 static phys_cpuid_t map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 40ebf1726393..af5297ef2293 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5600,6 +5600,10 @@ static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header,
 		goto node_err;
 	}
 
+	if (acpi_get_madt_revision() >= 7 &&
+	    (its_entry->flags & ACPI_MADT_ITS_NON_COHERENT))
+		its->flags |= ITS_FLAGS_FORCE_NON_SHAREABLE;
+
 	err = its_probe_one(its);
 	if (!err)
 		return 0;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 6fb276504bcc..e4bc5f04226e 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -2349,6 +2349,11 @@ gic_acpi_parse_madt_redist(union acpi_subtable_headers *header,
 		pr_err("Couldn't map GICR region @%llx\n", redist->base_address);
 		return -ENOMEM;
 	}
+
+	if (acpi_get_madt_revision() >= 7 &&
+	    (redist->flags & ACPI_MADT_GICR_NON_COHERENT))
+		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
+
 	gic_request_region(redist->base_address, redist->length, "GICR");
 
 	gic_acpi_register_redist(redist->base_address, redist_base);
@@ -2373,6 +2378,10 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 		return -ENOMEM;
 	gic_request_region(gicc->gicr_base_address, size, "GICR");
 
+	if (acpi_get_madt_revision() >= 7 &&
+	    (gicc->flags & ACPI_MADT_GICC_NON_COHERENT))
+		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
+
 	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
 	return 0;
 }
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 28c3fb2bef0d..000d339e1596 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -279,6 +279,9 @@ static inline bool invalid_phys_cpuid(phys_cpuid_t phys_id)
 	return phys_id == PHYS_CPUID_INVALID;
 }
 
+
+int __init acpi_get_madt_revision(void);
+
 /* Validate the processor object's proc_id */
 bool acpi_duplicate_processor_id(int proc_id);
 /* Processor _CTS control */
-- 
2.34.1

[PATCH v6 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by Amit Singh Tomar 11 months, 1 week ago

> ----------------------------------------------------------------------
> The GIC architecture specification defines a set of registers for
> redistributors and ITSes that control the sharebility and cacheability
> attributes of redistributors/ITSes initiator ports on the interconnect
> (GICR_[V]PROPBASER, GICR_[V]PENDBASER, GITS_BASER<n>).
> 
> Architecturally the GIC provides a means to drive shareability and
> cacheability attributes signals but it is not mandatory for designs to
> wire up the corresponding interconnect signals that control the
> cacheability/shareability of transactions.
> 
> Redistributors and ITSes interconnect ports can be connected to
> non-coherent interconnects that are not able to manage the
> shareability/cacheability attributes; this implicitly makes the
> redistributors and ITSes non-coherent observers.
> 
> To enable non-coherent GIC designs on ACPI based systems, parse the MADT
> GICC/GICR/ITS subtables non-coherent flags to determine whether the
> respective components are non-coherent observers and force the
> shareability attributes to be programmed into the redistributors and
> ITSes registers.
> 
> An ACPI global function (acpi_get_madt_revision()) is added to retrieve
> the MADT revision, in that it is essential to check the MADT revision
> before checking for flags that were added with MADT revision 7 so that
> if the kernel is booted with an ACPI MADT table with revision < 7 it
> skips parsing the newly added flags (that should be zeroed reserved
> values for MADT versions < 7 but they could turn out to be buggy and
> should be ignored).
> 
> Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Acked-by: Marc Zyngier <maz@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
> Cc: Marc Zyngier <maz@kernel.org>
> ---
>   drivers/acpi/processor_core.c    | 15 +++++++++++++++
>   drivers/irqchip/irq-gic-v3-its.c |  4 ++++
>   drivers/irqchip/irq-gic-v3.c     |  9 +++++++++
>   include/linux/acpi.h             |  3 +++
>   4 files changed, 31 insertions(+)
> 
> diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
> index b203cfe28550..915713c0e9b7 100644
> --- a/drivers/acpi/processor_core.c
> +++ b/drivers/acpi/processor_core.c
> @@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
>   	return rv;
>   }
>   
> +int __init acpi_get_madt_revision(void)

Wondering, if we can have a generic function (acpi_get_tbl_revision) to 
obtain the revision number for any ACPI table, not just specific to MADT?

> +{
> +	struct acpi_table_header *madt = NULL;
> +	int revision;
> +
> +	if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0, &madt)))
> +		return -EINVAL;
> +
> +	revision = madt->revision;
> +
> +	acpi_put_table(madt);
> +
> +	return revision;
> +}
> +
>   static phys_cpuid_t map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
>   {
>   	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 40ebf1726393..af5297ef2293 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c
> @@ -5600,6 +5600,10 @@ static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header,
>   		goto node_err;
>   	}
>   
> +	if (acpi_get_madt_revision() >= 7 &&
> +	    (its_entry->flags & ACPI_MADT_ITS_NON_COHERENT))
> +		its->flags |= ITS_FLAGS_FORCE_NON_SHAREABLE;
> +
>   	err = its_probe_one(its);
>   	if (!err)
>   		return 0;
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 6fb276504bcc..e4bc5f04226e 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -2349,6 +2349,11 @@ gic_acpi_parse_madt_redist(union acpi_subtable_headers *header,
>   		pr_err("Couldn't map GICR region @%llx\n", redist->base_address);
>   		return -ENOMEM;
>   	}
> +
> +	if (acpi_get_madt_revision() >= 7 &&
> +	    (redist->flags & ACPI_MADT_GICR_NON_COHERENT))
> +		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
> +
>   	gic_request_region(redist->base_address, redist->length, "GICR");
>   
>   	gic_acpi_register_redist(redist->base_address, redist_base);
> @@ -2373,6 +2378,10 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
>   		return -ENOMEM;
>   	gic_request_region(gicc->gicr_base_address, size, "GICR");
>   
> +	if (acpi_get_madt_revision() >= 7 &&
> +	    (gicc->flags & ACPI_MADT_GICC_NON_COHERENT))
> +		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
> +
>   	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
>   	return 0;
>   }
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 28c3fb2bef0d..000d339e1596 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -279,6 +279,9 @@ static inline bool invalid_phys_cpuid(phys_cpuid_t phys_id)
>   	return phys_id == PHYS_CPUID_INVALID;
>   }
>   
> +
> +int __init acpi_get_madt_revision(void);
> +
>   /* Validate the processor object's proc_id */
>   bool acpi_duplicate_processor_id(int proc_id);
>   /* Processor _CTS control */

Re: [PATCH v6 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by Lorenzo Pieralisi 11 months, 1 week ago

On Fri, Jun 07, 2024 at 12:21:54AM +0530, Amit Singh Tomar wrote:

[...]

> > diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
> > index b203cfe28550..915713c0e9b7 100644
> > --- a/drivers/acpi/processor_core.c
> > +++ b/drivers/acpi/processor_core.c
> > @@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
> >   	return rv;
> >   }
> > +int __init acpi_get_madt_revision(void)
> 
> Wondering, if we can have a generic function (acpi_get_tbl_revision) to
> obtain the revision number for any ACPI table, not just specific to MADT?

We could - I don't think there would be users other than code in this
patch though so I thought it would not be necessary.

Lorenzo

Re: [PATCH v6 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by Amit Singh Tomar 11 months, 1 week ago

> On Fri, Jun 07, 2024 at 12:21:54AM +0530, Amit Singh Tomar wrote:
> 
> [...]
> 
>>> diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
>>> index b203cfe28550..915713c0e9b7 100644
>>> --- a/drivers/acpi/processor_core.c
>>> +++ b/drivers/acpi/processor_core.c
>>> @@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
>>>    	return rv;
>>>    }
>>> +int __init acpi_get_madt_revision(void)
>>
>> Wondering, if we can have a generic function (acpi_get_tbl_revision) to
>> obtain the revision number for any ACPI table, not just specific to MADT?
> 
> We could - I don't think there would be users other than code in this
> patch though so I thought it would not be necessary.
> 

Right, it might not be essential now but I see that MPAM will be another 
user of it once the MPAM patches are out.

https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/tree/drivers/acpi/arm64/mpam.c?h=mpam/snapshot/v6.7-rc2#n299

Thanks
-Amit

Re: [PATCH v6 1/1] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by Robin Murphy 11 months, 1 week ago

On 2024-06-07 8:53 am, Amit Singh Tomar wrote:
>> On Fri, Jun 07, 2024 at 12:21:54AM +0530, Amit Singh Tomar wrote:
>>
>> [...]
>>
>>>> diff --git a/drivers/acpi/processor_core.c 
>>>> b/drivers/acpi/processor_core.c
>>>> index b203cfe28550..915713c0e9b7 100644
>>>> --- a/drivers/acpi/processor_core.c
>>>> +++ b/drivers/acpi/processor_core.c
>>>> @@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 
>>>> acpi_id)
>>>>        return rv;
>>>>    }
>>>> +int __init acpi_get_madt_revision(void)
>>>
>>> Wondering, if we can have a generic function (acpi_get_tbl_revision) to
>>> obtain the revision number for any ACPI table, not just specific to 
>>> MADT?
>>
>> We could - I don't think there would be users other than code in this
>> patch though so I thought it would not be necessary.
>>
> 
> Right, it might not be essential now but I see that MPAM will be another 
> user of it once the MPAM patches are out.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/tree/drivers/acpi/arm64/mpam.c?h=mpam/snapshot/v6.7-rc2#n299

Not really; there's already plenty of ACPI code which checks the 
revision of a table *while* also parsing other information from it, and 
that MPAM code is doing the same. Using a standalone function to look up 
the table, check one thing and throw it away, and then immediately have 
to look it up again to do the rest would be needlessly overcomplicated.

The thing in the GIC case is that doing this semi-redundant lookup to 
re-retrieve the top-level MADT header while we're already deep into 
parsing its subtables is still the least-worst option, because the 
alternative would be invasively churning the whole common MADT 
abstraction to pass that information all the way down just for this one 
slightly niche thing.

Thanks,
Robin.

[tip: irq/core] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

Posted by tip-bot2 for Lorenzo Pieralisi 11 months, 1 week ago

The following commit has been merged into the irq/core branch of tip:

Commit-ID:     ababa16fd9bd0e2727a1c31c4fb68d6be053bddc
Gitweb:        https://git.kernel.org/tip/ababa16fd9bd0e2727a1c31c4fb68d6be053bddc
Author:        Lorenzo Pieralisi <lpieralisi@kernel.org>
AuthorDate:    Thu, 06 Jun 2024 11:42:38 +02:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 06 Jun 2024 16:30:15 +02:00

irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

The GIC architecture specification defines a set of registers for
redistributors and ITSes that control the sharebility and cacheability
attributes of redistributors/ITSes initiator ports on the interconnect
(GICR_[V]PROPBASER, GICR_[V]PENDBASER, GITS_BASER<n>).

Architecturally the GIC provides a means to drive shareability and
cacheability attributes signals but it is not mandatory for designs to
wire up the corresponding interconnect signals that control the
cacheability/shareability of transactions.

Redistributors and ITSes interconnect ports can be connected to
non-coherent interconnects that are not able to manage the
shareability/cacheability attributes; this implicitly makes the
redistributors and ITSes non-coherent observers.

To enable non-coherent GIC designs on ACPI based systems, parse the MADT
GICC/GICR/ITS subtables non-coherent flags to determine whether the
respective components are non-coherent observers and force the
shareability attributes to be programmed into the redistributors and
ITSes registers.

An ACPI global function (acpi_get_madt_revision()) is added to retrieve
the MADT revision, in that it is essential to check the MADT revision
before checking for flags that were added with MADT revision 7 so that
if the kernel is booted with an ACPI MADT table with revision < 7 it
skips parsing the newly added flags (that should be zeroed reserved
values for MADT versions < 7 but they could turn out to be buggy and
should be ignored).

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: https://lore.kernel.org/r/20240606094238.757649-2-lpieralisi@kernel.org
---
 drivers/acpi/processor_core.c    | 15 +++++++++++++++
 drivers/irqchip/irq-gic-v3-its.c |  4 ++++
 drivers/irqchip/irq-gic-v3.c     |  9 +++++++++
 include/linux/acpi.h             |  3 +++
 4 files changed, 31 insertions(+)

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index b203cfe..915713c 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -215,6 +215,21 @@ phys_cpuid_t __init acpi_map_madt_entry(u32 acpi_id)
 	return rv;
 }
 
+int __init acpi_get_madt_revision(void)
+{
+	struct acpi_table_header *madt = NULL;
+	int revision;
+
+	if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0, &madt)))
+		return -EINVAL;
+
+	revision = madt->revision;
+
+	acpi_put_table(madt);
+
+	return revision;
+}
+
 static phys_cpuid_t map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 40ebf17..af5297e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5600,6 +5600,10 @@ static int __init gic_acpi_parse_madt_its(union acpi_subtable_headers *header,
 		goto node_err;
 	}
 
+	if (acpi_get_madt_revision() >= 7 &&
+	    (its_entry->flags & ACPI_MADT_ITS_NON_COHERENT))
+		its->flags |= ITS_FLAGS_FORCE_NON_SHAREABLE;
+
 	err = its_probe_one(its);
 	if (!err)
 		return 0;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 6fb2765..e4bc5f0 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -2349,6 +2349,11 @@ gic_acpi_parse_madt_redist(union acpi_subtable_headers *header,
 		pr_err("Couldn't map GICR region @%llx\n", redist->base_address);
 		return -ENOMEM;
 	}
+
+	if (acpi_get_madt_revision() >= 7 &&
+	    (redist->flags & ACPI_MADT_GICR_NON_COHERENT))
+		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
+
 	gic_request_region(redist->base_address, redist->length, "GICR");
 
 	gic_acpi_register_redist(redist->base_address, redist_base);
@@ -2373,6 +2378,10 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
 		return -ENOMEM;
 	gic_request_region(gicc->gicr_base_address, size, "GICR");
 
+	if (acpi_get_madt_revision() >= 7 &&
+	    (gicc->flags & ACPI_MADT_GICC_NON_COHERENT))
+		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
+
 	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
 	return 0;
 }
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 28c3fb2..000d339 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -279,6 +279,9 @@ static inline bool invalid_phys_cpuid(phys_cpuid_t phys_id)
 	return phys_id == PHYS_CPUID_INVALID;
 }
 
+
+int __init acpi_get_madt_revision(void);
+
 /* Validate the processor object's proc_id */
 bool acpi_duplicate_processor_id(int proc_id);
 /* Processor _CTS control */