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@xxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
---
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 fec1b58470df..a60c560ce891 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5591,6 +5591,10 @@ 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 98b0329b7154..8cb8dff86c12 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -2356,6 +2356,11 @@ 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);
@@ -2380,6 +2385,10 @@ 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 b7165e52b3c6..4eedab0e51c3 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -284,6 +284,9 @@ 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
