[kvm-unit-tests PATCH v3 04/27] lib: Add support for the XSDT ACPI table

Nikos Nikoleris
2022-06-30T10:04:01Z

XSDT provides pointers to other ACPI tables much like RSDT. However,
contrary to RSDT that provides 32-bit addresses, XSDT provides 64-bit
pointers. ACPI requires that if XSDT is valid then it takes precedence
over RSDT.

Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
---
lib/acpi.h | 6 ++++++
lib/acpi.c | 37 +++++++++++++++++++++++++++++++------
2 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/lib/acpi.h b/lib/acpi.h
index b853a55..c5f0aa5 100644
--- a/lib/acpi.h
+++ b/lib/acpi.h
@@ -14,6 +14,7 @@

#define RSDP_SIGNATURE ACPI_SIGNATURE('R','S','D','P')
#define RSDT_SIGNATURE ACPI_SIGNATURE('R','S','D','T')
+#define XSDT_SIGNATURE ACPI_SIGNATURE('X','S','D','T')
#define FACP_SIGNATURE ACPI_SIGNATURE('F','A','C','P')
#define FACS_SIGNATURE ACPI_SIGNATURE('F','A','C','S')

@@ -57,6 +58,11 @@ struct rsdt_descriptor_rev1 {
u32 table_offset_entry[1];
};

+struct acpi_table_xsdt {
+ ACPI_TABLE_HEADER_DEF
+ u64 table_offset_entry[1];
+};
+
struct fadt_descriptor_rev1
{
ACPI_TABLE_HEADER_DEF /* ACPI common table header */
diff --git a/lib/acpi.c b/lib/acpi.c
index b7fd923..240a922 100644
--- a/lib/acpi.c
+++ b/lib/acpi.c
@@ -40,6 +40,7 @@ void *find_acpi_table_addr(u32 sig)
{
struct rsdp_descriptor *rsdp;
struct rsdt_descriptor_rev1 *rsdt;
+ struct acpi_table_xsdt *xsdt = NULL;
void *end;
int i;

@@ -64,17 +65,41 @@ void *find_acpi_table_addr(u32 sig)

rsdt = (void *)(ulong)rsdp->rsdt_physical_address;
if (!rsdt || rsdt->signature != RSDT_SIGNATURE)
- return NULL;
+ rsdt = NULL;

if (sig == RSDT_SIGNATURE)
return rsdt;

- end = (void *)rsdt + rsdt->length;
- for (i = 0; (void *)&rsdt->table_offset_entry[i] < end; i++) {
- struct acpi_table *t = (void *)(ulong)rsdt->table_offset_entry[i];
- if (t && t->signature == sig) {
- return t;
+ /*
+ * When the system implements APCI 2.0 and above and XSDT is
+ * valid we have use XSDT to find other ACPI tables,
+ * otherwise, we use RSDT.
+ */
+ if (rsdp->revision == 2)
+ xsdt = (void *)(ulong)rsdp->xsdt_physical_address;
+ if (!xsdt || xsdt->signature != XSDT_SIGNATURE)
+ xsdt = NULL;
+
+ if (sig == XSDT_SIGNATURE)
+ return xsdt;
+
+ if (xsdt) {
+ end = (void *)(ulong)xsdt + xsdt->length;
+ for (i = 0; (void *)&xsdt->table_offset_entry[i] < end; i++) {
+ struct acpi_table *t = (void *)xsdt->table_offset_entry[i];
+
+ if (t && t->signature == sig)
+ return t;
+ }
+ } else if (rsdt) {
+ end = (void *)rsdt + rsdt->length;
+ for (i = 0; (void *)&rsdt->table_offset_entry[i] < end; i++) {
+ struct acpi_table *t = (void *)(ulong)rsdt->table_offset_entry[i];
+
+ if (t && t->signature == sig)
+ return t;
}
}
+
return NULL;
}
--
2.25.1