Hello Julien,
On 12/21/25 11:28 AM, Julien Grall wrote:
Hi Oleksii,
On 18/12/2025 14:22, Oleksii Kurochko wrote:
Newer ACPI revisions define the MADT GICC entry with Length = 82
bytes [1].
The current BAD_MADT_GICC_ENTRY() check rejects entries whose length
does not
match the known values, which leads to:
GICv3: No valid GICC entries exist.
as observed on the AmpereOne platform.
To fix this, import the logic from import from Linux commit 9eb1c92:
Shouldn't this be s/from import//?
Agree, 'from import' should be dropped.
Also 7 characters commit ID is too short for Linux and known to clash.
You want to use 12 characters (which is also the default for Xen). I
usually have the following in my global .gitconfig:
[core]
abbrev = 12
I'll add the same, thanks for advise.
The BAD_MADT_GICC_ENTRY check is a little too strict because
it rejects MADT entries that don't match the currently known
lengths. We should remove this restriction to avoid problems
if the table length changes. Future code which might depend on
additional fields should be written to validate those fields
before using them, rather than trying to globally check
known MADT version lengths.
Link:
https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jeremy Linton <[email protected]>
[[email protected]: added MADT macro comments]
Signed-off-by: Lorenzo Pieralisi <[email protected]>
Acked-by: Sudeep Holla <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Al Stone <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
As ACPI_MADT_GICC_LENGTH is dropped, update the functions where it is
used. As we rewrite the MADT for hwdom, reuse the host GICC header
length
instead of ACPI_MADT_GICC_LENGTH.
[1]
https://uefi.org/specs/ACPI/6.6/05_ACPI_Software_Programming_Model.html#gic-cpu-interface-gicc-structure
Reported-By: Yann Dirson <[email protected]>
Co-developed-by: Yann Sionneau <[email protected]>
Signed-off-by: Oleksii Kurochko <[email protected]>
---
I ran CI tests where it made sense for this patch, as I don’t see any
CI job
that builds Xen with CONFIG_ACPI=y:
https://gitlab.com/xen-project/people/olkur/xen/-/pipelines/2222160666
I also built Xen manually with CONFIG_ACPI=y enabled and tested it on
the
AmpereOne platform.
---
xen/arch/arm/gic-v2.c | 3 ++-
xen/arch/arm/gic-v3.c | 3 ++-
xen/arch/arm/gic.c | 12 +++++++++++-
xen/arch/arm/include/asm/acpi.h | 21 +++++++++++++++------
4 files changed, 30 insertions(+), 9 deletions(-)
diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index b23e72a3d0..aae6a7bf30 100644
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -1121,7 +1121,8 @@ static int gicv2_make_hwdom_madt(const struct
domain *d, u32 offset)
host_gicc = container_of(header, struct
acpi_madt_generic_interrupt,
header);
- size = ACPI_MADT_GICC_LENGTH;
+ size = host_gicc->header.length;
+
/* Add Generic Interrupt */
for ( i = 0; i < d->max_vcpus; i++ )
{
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index bc07f97c16..75b89efad4 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -1672,7 +1672,8 @@ static int gicv3_make_hwdom_madt(const struct
domain *d, u32 offset)
host_gicc = container_of(header, struct
acpi_madt_generic_interrupt,
header);
- size = ACPI_MADT_GICC_LENGTH;
+ size = host_gicc->header.length;
+
for ( i = 0; i < d->max_vcpus; i++ )
{
gicc = (struct acpi_madt_generic_interrupt *)(base_ptr +
table_len);
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index ee75258fc3..a0ccda14bf 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -418,8 +418,18 @@ unsigned long gic_get_hwdom_madt_size(const
struct domain *d)
{
unsigned long madt_size;
+ struct acpi_subtable_header *header;
+ struct acpi_madt_generic_interrupt *host_gicc;
For both variables, you don't seem to modify the content. So I think
they should be const.
+
+ header =
acpi_table_get_entry_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT, 0);
+ if ( !header )
+ panic("Can't get GICC entry");
I would feel happier to use panic() in this function if
gic_get_hwdom_madt_size() is __init (its only caller is during boot)).
I am okay with making gic_get_hwdom_madt_size() as __init.
An alternative is to stash the GICC size in a global variable.
We also could to return 0 in the case of ( !header ) and then check if the size
is zero or not in estimate_acpi_efi_size(),
and if it is zero then just return -EINVAL. Does it make sense?
Thanks!
~ Oleksii
+
+ host_gicc = container_of(header, struct
acpi_madt_generic_interrupt,
+ header);
+
madt_size = sizeof(struct acpi_table_madt)
- + ACPI_MADT_GICC_LENGTH * d->max_vcpus
+ + host_gicc->header.length * d->max_vcpus
+ sizeof(struct acpi_madt_generic_distributor)
+ gic_hw_ops->get_hwdom_extra_madt_size(d);
diff --git a/xen/arch/arm/include/asm/acpi.h
b/xen/arch/arm/include/asm/acpi.h
index 13756dd341..30bc446d1f 100644
--- a/xen/arch/arm/include/asm/acpi.h
+++ b/xen/arch/arm/include/asm/acpi.h
@@ -53,13 +53,22 @@ void acpi_smp_init_cpus(void);
*/
paddr_t acpi_get_table_offset(struct membank tbl_add[], EFI_MEM_RES
index);
-/* Macros for consistency checks of the GICC subtable of MADT */
-#define ACPI_MADT_GICC_LENGTH \
- (acpi_gbl_FADT.header.revision < 6 ? 76 : 80)
+/*
+ * MADT GICC minimum length refers to the MADT GICC structure table
length as
+ * defined in the earliest ACPI version supported on arm64, ie ACPI
5.1.
+ *
+ * The efficiency_class member was added to the
+ * struct acpi_madt_generic_interrupt to represent the MADT GICC
structure
+ * "Processor Power Efficiency Class" field, added in ACPI 6.0 whose
offset
+ * is therefore used to delimit the MADT GICC structure minimum length
+ * appropriately.
+ */
+#define ACPI_MADT_GICC_MIN_LENGTH ACPI_OFFSET( \
+ struct acpi_madt_generic_interrupt, efficiency_class)
-#define BAD_MADT_GICC_ENTRY(entry, end) \
- (!(entry) || (unsigned long)(entry) + sizeof(*(entry)) > (end)
|| \
- (entry)->header.length != ACPI_MADT_GICC_LENGTH)
+#define BAD_MADT_GICC_ENTRY(entry, end) \
+ (!(entry) || (entry)->header.length < ACPI_MADT_GICC_MIN_LENGTH
|| \
+ (unsigned long)(entry) + (entry)->header.length > (end))
#ifdef CONFIG_ACPI
extern bool acpi_disabled;
Cheers,
