[Qemu-devel] [PATCH hack dontapply v2 6/7] acpi: aml generation for _CST

["Michael S. Tsirkin" <mst@redhat.com>]

This adds a method called CCST under CPUS.
Each CPU will add _CST calling in turn CCST from there.

As _CST needs to change across migration, we use
dynamic loading of tables as follows:

- a special scratch buffer, 4K in size is requested from bios
  through the loader.
- each time CCST executes, buffer address is passed to QEMU
  which will write an SSDT table with the _CST package into the buffer.
- table is then loaded and a package named \\_SB.CPUS.CSTL is loaded from there.
- table is unloaded, package is then returned to caller

In this way, QEMU can change the package across migration.
It will then notify the OSPM which will re-evaluate
_CST.

In this proof of concept patch, package generation itself is
still a stub, and change notifications are missing.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/acpi/cst.h |   8 ++
 hw/acpi/cst.c         | 173 ++++++++++++++++++++++++++++++++++++++++++
 hw/acpi/Makefile.objs |   2 +-
 3 files changed, 182 insertions(+), 1 deletion(-)
 create mode 100644 include/hw/acpi/cst.h
 create mode 100644 hw/acpi/cst.c

diff --git a/include/hw/acpi/cst.h b/include/hw/acpi/cst.h
new file mode 100644
index 0000000000..2e40e87881
--- /dev/null
+++ b/include/hw/acpi/cst.h
@@ -0,0 +1,8 @@
+#ifndef HW_ACPI_CST_H
+#define HW_ACPI_CST_H
+
+#include "hw/acpi/bios-linker-loader.h"
+
+void cst_build_acpi(GArray *table_data, BIOSLinker *linker, uint16_t ioport);
+void cst_register(FWCfgState *s, uint16_t ioport);
+#endif
diff --git a/hw/acpi/cst.c b/hw/acpi/cst.c
new file mode 100644
index 0000000000..20dd80aef8
--- /dev/null
+++ b/hw/acpi/cst.c
@@ -0,0 +1,173 @@
+#include "qemu/osdep.h"
+#include "exec/address-spaces.h"
+#include "hw/acpi/aml-build.h"
+#include "hw/acpi/cst.h"
+#include "hw/acpi/acpi.h"
+#include "hw/nvram/fw_cfg.h"
+
+#define ACPI_SCRATCH_BUFFER_NAME "etc/scratch"
+
+/* Hack! Incomplete! */
+static Aml *build_cst_package(void)
+{
+    int i;
+    Aml *crs;
+    Aml *pkg;
+    int cs_num = 3;
+
+    pkg = aml_package(cs_num + 1); /* # of ACPI Cx states + state count */
+    aml_append(pkg, aml_int(cs_num)); /* # of ACPI Cx states */
+
+    for (i = 0; i < cs_num; i++) {
+        Aml *cstate = aml_package(4);
+
+        crs = aml_resource_template();
+        aml_append(crs, aml_register(AML_AS_SYSTEM_IO,
+            0x8,
+            0x0,
+            0x100,
+            0x1));
+        aml_append(cstate, crs);
+        aml_append(cstate, aml_int(i + 1)); /* Cx ACPI state */
+        aml_append(cstate, aml_int((i + 1) * 10)); /* Latency */
+        aml_append(cstate, aml_int(cs_num - i - 1));/* Power */
+        aml_append(pkg, cstate);
+    }
+
+    return pkg;
+}
+
+static GArray *cst_scratch;
+
+/*
+ * Add an SSDT with a dynamic method named CCST. The method uses the specified
+ * ioport to load a table from QEMU, then returns an object named CSTL from
+ * it.
+ * Everything is scoped under \\_SB.CPUS.CSTP.
+ */
+void cst_build_acpi(GArray *table_data, BIOSLinker *linker, uint16_t ioport)
+{
+    Aml *ssdt, *scope, *field, *method;
+    uint32_t cstp_offset;
+
+    /* Put this in a separate SSDT table */
+    ssdt = init_aml_allocator();
+
+    /* Reserve space for header */
+    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
+
+    cstp_offset = table_data->len +
+        build_append_named_dword(ssdt->buf, "\\_SB.CPUS.CSTP");
+    scope = aml_scope("\\_SB.CPUS");
+    {
+        /* buffer in reserved memory to load the table from */
+        aml_append(scope, aml_operation_region("CSTB", AML_SYSTEM_MEMORY,
+                                               aml_name("\\_SB.CPUS.CSTP"),
+                                               4096));
+        /* write address here to update the table in memory */
+        aml_append(scope, aml_operation_region("CSTR", AML_SYSTEM_IO,
+                                               aml_int(ioport),
+                                               4));
+        field = aml_field("CSTR", AML_DWORD_ACC, AML_LOCK,
+                          AML_WRITE_AS_ZEROS);
+        {
+            aml_append(field, aml_named_field("CSTU", 32));
+        }
+        aml_append(scope, field);
+        method = aml_method("CCST", 0, AML_SERIALIZED);
+        {
+            Aml *ddbhandle = aml_local(0);
+            Aml *cst = aml_local(1);
+            /* Write buffer address to update table in memory. */
+            aml_append(method, aml_store(aml_name("CSTP"), aml_name("CSTU")));
+            aml_append(method, aml_load("CSTB", ddbhandle));
+            aml_append(method, aml_store(aml_name("CSTL"), cst));
+            aml_append(method, aml_unload(ddbhandle));
+            aml_append(method, aml_return(cst));
+        }
+        aml_append(scope, method);
+    }
+    aml_append(ssdt, scope);
+    g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
+
+    /* Why page boundary? no special reason right now but seems like
+     * a good idea for future extensions.      
+    */
+    bios_linker_loader_alloc(linker, ACPI_SCRATCH_BUFFER_NAME, cst_scratch,
+                             4096, false /* page boundary, high memory */);
+    /* Patch address of allocated memory into the AML so OSPM can retrieve
+     * and read it.
+     */
+    bios_linker_loader_add_pointer(linker,
+        ACPI_BUILD_TABLE_FILE, cstp_offset, sizeof(uint32_t),
+        ACPI_SCRATCH_BUFFER_NAME, 0);
+
+    //table_data->data[cstp_offset] = 0x8; /* hack */
+
+    build_header(linker, table_data,
+        (void *)(table_data->data + table_data->len - ssdt->buf->len),
+        "SSDT", ssdt->buf->len, 1, NULL, "CSTSSDT");
+
+    free_aml_allocator();
+}
+
+static GArray *cst_ssdt;
+
+static void cst_ssdt_setup(void)
+{
+    AcpiTableHeader *dyn_ssdt_hdr;
+    Aml *dyn_ssdt = init_aml_allocator();
+
+    /* Reserve space for header */
+    acpi_data_push(dyn_ssdt->buf, sizeof(AcpiTableHeader));
+    aml_append(dyn_ssdt, aml_name_decl("\\_SB.CPUS.CSTL", build_cst_package()));
+
+    dyn_ssdt_hdr = (AcpiTableHeader *)dyn_ssdt->buf->data;
+
+    acpi_init_header(dyn_ssdt_hdr, "SSDT", dyn_ssdt->buf->len, 1, NULL, "DYNSSDT");
+
+    dyn_ssdt_hdr->checksum = acpi_checksum((uint8_t *)dyn_ssdt_hdr,
+                                           dyn_ssdt->buf->len);
+
+    /* dyn_ssdt->buf will be freed. copy to cst_ssdt */
+    cst_ssdt = g_array_new(false, true, 1);
+    g_array_append_vals(cst_ssdt, dyn_ssdt->buf->data, dyn_ssdt->buf->len);
+
+    free_aml_allocator();
+}
+
+/* Update CST in system memory */
+static void cst_ioport_write(void *opaque, hwaddr addr, uint64_t data, unsigned size)
+{
+    assert(cst_ssdt);
+
+    cpu_physical_memory_write(data, cst_ssdt->data, cst_ssdt->len);
+}
+
+static const MemoryRegionOps cst_ops = {
+    .write = cst_ioport_write,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
+static MemoryRegion cst_mr;
+
+void cst_register(FWCfgState *s, uint16_t ioport)
+{
+    cst_ssdt_setup();
+
+    /* Allocate guest scratch memory for the table */
+    cst_scratch = g_array_new(false, true, 1);
+    acpi_data_push(cst_scratch, 4096);
+    fw_cfg_add_file(s, ACPI_SCRATCH_BUFFER_NAME, cst_scratch->data,
+                    cst_scratch->len);
+
+    /* setup io to trigger updates */
+    memory_region_init_io(&cst_mr, NULL, &cst_ops, NULL, "cst-update-request", 4);
+    memory_region_add_subregion(get_system_io(), ioport, &cst_mr);
+}
+
+/* TODO: API to notify guest of changes */
diff --git a/hw/acpi/Makefile.objs b/hw/acpi/Makefile.objs
index 11c35bcb44..0119367455 100644
--- a/hw/acpi/Makefile.objs
+++ b/hw/acpi/Makefile.objs
@@ -1,5 +1,5 @@
 ifeq ($(CONFIG_ACPI),y)
-common-obj-$(CONFIG_ACPI_X86) += core.o piix4.o pcihp.o
+common-obj-$(CONFIG_ACPI_X86) += core.o piix4.o pcihp.o cst.o
 common-obj-$(CONFIG_ACPI_X86_ICH) += ich9.o tco.o
 common-obj-$(CONFIG_ACPI_CPU_HOTPLUG) += cpu_hotplug.o
 common-obj-$(CONFIG_ACPI_MEMORY_HOTPLUG) += memory_hotplug.o
-- 
MST