[Qemu-devel] [PATCH] hw/arm/virt: generate 64-bit addressable ACPI objects

[Ard Biesheuvel]

Our current ACPI table generation code limits the placement of ACPI
tables to 32-bit addressable memory, in order to be able to emit the
root pointer (RSDP) and root table (RSDT) using table types from the
ACPI 1.0 days.

Since ARM was not supported by ACPI before version 5.0, it makes sense
to lift this restriction. This is not crucial for mach-virt, which is
guaranteed to have some memory available below the 4 GB mark, but it
is a nice to have for QEMU machines that do not have any 32-bit
addressable, not unlike some real world 64-bit ARM systems.

Since we already emit a version of the RSDP root pointer that carries
a 64-bit wide address for the 64-bit root table (XSDT), all we need to
do is replace the RSDT generation with the generation of an XSDT table,
and use a different slot in the FADT table to refer to the DSDT.

Note that this only modifies the private interaction between QEMU and
UEFI. Since these tables are all handled by the generic AcpiTableDxe
driver which generates its own RSDP, RSDT and XSDT tables and manages
the DSDT pointer in FADT itself, the tables that are present to the
guest are identical, and so no mach-virt versioning is required for
this change.

Signed-off-by: Ard Biesheuvel <address@hidden>
---
 hw/arm/virt-acpi-build.c    | 55 ++++++++++++++++++++++++++++++++++-----------
 include/hw/acpi/acpi-defs.h | 11 +++++++++
 2 files changed, 53 insertions(+), 13 deletions(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index b173bd109b91..d18368094c00 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -391,12 +391,12 @@ static void acpi_dsdt_add_power_button(Aml *scope)
 
 /* RSDP */
 static GArray *
-build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset)
+build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned xsdt_tbl_offset)
 {
     AcpiRsdpDescriptor *rsdp = acpi_data_push(rsdp_table, sizeof *rsdp);
-    unsigned rsdt_pa_size = sizeof(rsdp->rsdt_physical_address);
-    unsigned rsdt_pa_offset =
-        (char *)&rsdp->rsdt_physical_address - rsdp_table->data;
+    unsigned xsdt_pa_size = sizeof(rsdp->xsdt_physical_address);
+    unsigned xsdt_pa_offset =
+        (char *)&rsdp->xsdt_physical_address - rsdp_table->data;
 
     bios_linker_loader_alloc(linker, ACPI_BUILD_RSDP_FILE, rsdp_table, 16,
                              true /* fseg memory */);
@@ -408,8 +408,8 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned 
rsdt_tbl_offset)
 
     /* Address to be filled by Guest linker */
     bios_linker_loader_add_pointer(linker,
-        ACPI_BUILD_RSDP_FILE, rsdt_pa_offset, rsdt_pa_size,
-        ACPI_BUILD_TABLE_FILE, rsdt_tbl_offset);
+        ACPI_BUILD_RSDP_FILE, xsdt_pa_offset, xsdt_pa_size,
+        ACPI_BUILD_TABLE_FILE, xsdt_tbl_offset);
 
     /* Checksum to be filled by Guest linker */
     bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
@@ -686,7 +686,7 @@ static void build_fadt(GArray *table_data, BIOSLinker 
*linker,
                        VirtMachineState *vms, unsigned dsdt_tbl_offset)
 {
     AcpiFadtDescriptorRev5_1 *fadt = acpi_data_push(table_data, sizeof(*fadt));
-    unsigned dsdt_entry_offset = (char *)&fadt->dsdt - table_data->data;
+    unsigned xdsdt_entry_offset = (char *)&fadt->Xdsdt - table_data->data;
     uint16_t bootflags;
 
     switch (vms->psci_conduit) {
@@ -712,7 +712,7 @@ static void build_fadt(GArray *table_data, BIOSLinker 
*linker,
 
     /* DSDT address to be filled by Guest linker */
     bios_linker_loader_add_pointer(linker,
-        ACPI_BUILD_TABLE_FILE, dsdt_entry_offset, sizeof(fadt->dsdt),
+        ACPI_BUILD_TABLE_FILE, xdsdt_entry_offset, sizeof(fadt->Xdsdt),
         ACPI_BUILD_TABLE_FILE, dsdt_tbl_offset);
 
     build_header(linker, table_data,
@@ -772,12 +772,41 @@ struct AcpiBuildState {
     bool patched;
 } AcpiBuildState;
 
+/* Build xsdt table */
+
+static
+void build_xsdt(GArray *table_data, BIOSLinker *linker, GArray *table_offsets,
+                const char *oem_id, const char *oem_table_id)
+{
+    int i;
+    unsigned xsdt_entries_offset;
+    AcpiXsdtDescriptorRev2 *xsdt;
+    const unsigned table_data_len = (sizeof(uint64_t) * table_offsets->len);
+    const unsigned xsdt_entry_size = sizeof(xsdt->table_offset_entry[0]);
+    const size_t xsdt_len = sizeof(*xsdt) + table_data_len;
+
+    xsdt = acpi_data_push(table_data, xsdt_len);
+    xsdt_entries_offset = (char *)xsdt->table_offset_entry - table_data->data;
+    for (i = 0; i < table_offsets->len; ++i) {
+        uint64_t ref_tbl_offset = g_array_index(table_offsets, uint32_t, i);
+        uint64_t xsdt_entry_offset = xsdt_entries_offset + xsdt_entry_size * i;
+
+        /* xsdt->table_offset_entry to be filled by Guest linker */
+        bios_linker_loader_add_pointer(linker,
+            ACPI_BUILD_TABLE_FILE, xsdt_entry_offset, xsdt_entry_size,
+            ACPI_BUILD_TABLE_FILE, ref_tbl_offset);
+    }
+    build_header(linker, table_data,
+                 (void *)xsdt, "XSDT", xsdt_len, 1, oem_id, oem_table_id);
+}
+
+
 static
 void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
 {
     VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
     GArray *table_offsets;
-    unsigned dsdt, rsdt;
+    unsigned dsdt, xsdt;
     GArray *tables_blob = tables->table_data;
 
     table_offsets = g_array_new(false, true /* clear */,
@@ -817,12 +846,12 @@ void virt_acpi_build(VirtMachineState *vms, 
AcpiBuildTables *tables)
         build_iort(tables_blob, tables->linker);
     }
 
-    /* RSDT is pointed to by RSDP */
-    rsdt = tables_blob->len;
-    build_rsdt(tables_blob, tables->linker, table_offsets, NULL, NULL);
+    /* XSDT is pointed to by RSDP */
+    xsdt = tables_blob->len;
+    build_xsdt(tables_blob, tables->linker, table_offsets, NULL, NULL);
 
     /* RSDP is in FSEG memory, so allocate it separately */
-    build_rsdp(tables->rsdp, tables->linker, rsdt);
+    build_rsdp(tables->rsdp, tables->linker, xsdt);
 
     /* Cleanup memory that's no longer used. */
     g_array_free(table_offsets, true);
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index 4cc3630e613e..bf37acf4c4c6 100644
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -238,6 +238,17 @@ struct AcpiRsdtDescriptorRev1
 typedef struct AcpiRsdtDescriptorRev1 AcpiRsdtDescriptorRev1;
 
 /*
+ * ACPI 2.0 eXtended System Description Table (XSDT)
+ */
+struct AcpiXsdtDescriptorRev2
+{
+    ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
+    uint64_t table_offset_entry[0];  /* Array of pointers to other */
+    /* ACPI tables */
+} QEMU_PACKED;
+typedef struct AcpiXsdtDescriptorRev2 AcpiXsdtDescriptorRev2;
+
+/*
  * ACPI 1.0 Firmware ACPI Control Structure (FACS)
  */
 struct AcpiFacsDescriptorRev1
-- 
2.9.3