[v9,5/6] acpi: build TPM Physical Presence interface

Message ID 20180810153223.28409-6-marcandre.lureau@redhat.com
State New
Headers show
Series
  • [v9,1/6] hw/i386: add pc-i440fx-3.1 & pc-q35-3.1
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Commit Message

Marc-André Lureau Aug. 10, 2018, 3:32 p.m.
From: Stefan Berger <stefanb@linux.vnet.ibm.com>

The TPM Physical Presence interface consists of an ACPI part, a shared
memory part, and code in the firmware. Users can send messages to the
firmware by writing a code into the shared memory through invoking the
ACPI code. When a reboot happens, the firmware looks for the code and
acts on it by sending sequences of commands to the TPM.

This patch adds the ACPI code. It is similar to the one in EDK2 but doesn't
assume that SMIs are necessary to use. It uses a similar datastructure for
the shared memory as EDK2 does so that EDK2 and SeaBIOS could both make use
of it. I extended the shared memory data structure with an array of 256
bytes, one for each code that could be implemented. The array contains
flags describing the individual codes. This decouples the ACPI implementation
from the firmware implementation.

The underlying TCG specification is accessible from the following page.

https://trustedcomputinggroup.org/tcg-physical-presence-interface-specification/

This patch implements version 1.30.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
[ Marc-André - ACPI code improvements and windows fixes ]
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
---
 include/hw/acpi/tpm.h |   8 +
 hw/i386/acpi-build.c  | 393 +++++++++++++++++++++++++++++++++++++++++-
 docs/specs/tpm.txt    |  79 +++++++++
 3 files changed, 477 insertions(+), 3 deletions(-)

Patch

diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
index a6109a97fc..ecccb96933 100644
--- a/include/hw/acpi/tpm.h
+++ b/include/hw/acpi/tpm.h
@@ -197,4 +197,12 @@  REG32(CRB_DATA_BUFFER, 0x80)
 #define TPM_PPI_VERSION_NONE        0
 #define TPM_PPI_VERSION_1_30        1
 
+/* whether function is blocked by BIOS settings; bits 0, 1, 2 */
+#define TPM_PPI_FUNC_NOT_IMPLEMENTED     (0 << 0)
+#define TPM_PPI_FUNC_BIOS_ONLY           (1 << 0)
+#define TPM_PPI_FUNC_BLOCKED             (2 << 0)
+#define TPM_PPI_FUNC_ALLOWED_USR_REQ     (3 << 0)
+#define TPM_PPI_FUNC_ALLOWED_USR_NOT_REQ (4 << 0)
+#define TPM_PPI_FUNC_MASK                (7 << 0)
+
 #endif /* HW_ACPI_TPM_H */
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index c24f68df02..c5e9a6e11d 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -43,6 +43,7 @@ 
 #include "hw/acpi/memory_hotplug.h"
 #include "sysemu/tpm.h"
 #include "hw/acpi/tpm.h"
+#include "hw/tpm/tpm_ppi.h"
 #include "hw/acpi/vmgenid.h"
 #include "sysemu/tpm_backend.h"
 #include "hw/timer/mc146818rtc_regs.h"
@@ -1789,6 +1790,386 @@  static Aml *build_q35_osc_method(void)
     return method;
 }
 
+static void
+build_tpm_ppi(TPMIf *tpm, Aml *dev)
+{
+    Aml *method, *field, *ifctx, *ifctx2, *ifctx3, *func_mask,
+        *not_implemented, *pak, *tpm2, *tpm3, *pprm, *pprq, *zero, *one;
+
+    if (!object_property_get_bool(OBJECT(tpm), "ppi", &error_abort)) {
+        return;
+    }
+
+    zero = aml_int(0);
+    one = aml_int(1);
+    func_mask = aml_int(TPM_PPI_FUNC_MASK);
+    not_implemented = aml_int(TPM_PPI_FUNC_NOT_IMPLEMENTED);
+
+    /*
+     * TPP2 is for the registers that ACPI code used to pass
+     * the PPI code and parameter (PPRQ, PPRM) to the firmware.
+     */
+    aml_append(dev,
+               aml_operation_region("TPP2", AML_SYSTEM_MEMORY,
+                                    aml_int(TPM_PPI_ADDR_BASE + 0x100),
+                                    0x5A));
+    field = aml_field("TPP2", AML_ANY_ACC, AML_NOLOCK, AML_PRESERVE);
+    aml_append(field, aml_named_field("PPIN", 8));
+    aml_append(field, aml_named_field("PPIP", 32));
+    aml_append(field, aml_named_field("PPRP", 32));
+    aml_append(field, aml_named_field("PPRQ", 32));
+    aml_append(field, aml_named_field("PPRM", 32));
+    aml_append(field, aml_named_field("LPPR", 32));
+    aml_append(dev, field);
+    pprq = aml_name("PPRQ");
+    pprm = aml_name("PPRM");
+
+    /*
+     * DerefOf in Windows is broken with SYSTEM_MEMORY.  Use a dynamic
+     * operation region inside of a method for getting FUNC[op].
+     */
+    method = aml_method("TPFN", 1, AML_SERIALIZED);
+    {
+        Aml *op = aml_arg(0);
+        ifctx = aml_if(aml_lgreater_equal(op, aml_int(0x100)));
+        {
+            aml_append(ifctx, aml_return(zero));
+        }
+        aml_append(method, ifctx);
+
+        aml_append(method,
+            aml_operation_region("TPP1", AML_SYSTEM_MEMORY,
+                aml_add(aml_int(TPM_PPI_ADDR_BASE), op, NULL), 0x1));
+        field = aml_field("TPP1", AML_BYTE_ACC, AML_NOLOCK, AML_PRESERVE);
+        aml_append(field, aml_named_field("TPPF", 8));
+        aml_append(method, field);
+        aml_append(method, aml_return(aml_name("TPPF")));
+    }
+    aml_append(dev, method);
+
+    /*
+     * Use global TPM2 & TPM3 variables to workaround Windows ACPI bug
+     * when returning packages.
+     */
+    pak = aml_package(2);
+    aml_append(pak, zero);
+    aml_append(pak, zero);
+    aml_append(dev, aml_name_decl("TPM2", pak));
+    tpm2 = aml_name("TPM2");
+
+    pak = aml_package(3);
+    aml_append(pak, zero);
+    aml_append(pak, zero);
+    aml_append(pak, zero);
+    aml_append(dev, aml_name_decl("TPM3", pak));
+    tpm3 = aml_name("TPM3");
+
+    method = aml_method("_DSM", 4, AML_SERIALIZED);
+    {
+        uint8_t zerobyte[1] = { 0 };
+        Aml *function, *arguments, *rev, *op, *op_arg, *op_flags, *uuid;
+
+        uuid = aml_arg(0);
+        rev = aml_arg(1);
+        function = aml_arg(2);
+        arguments = aml_arg(3);
+        op = aml_local(0);
+        op_flags = aml_local(1);
+
+        ifctx = aml_if(
+            aml_equal(uuid,
+                      aml_touuid("3DDDFAA6-361B-4EB4-A424-8D10089D1653")));
+        {
+            /* standard DSM query function */
+            ifctx2 = aml_if(aml_equal(function, zero));
+            {
+                uint8_t byte_list[2] = { 0xff, 0x01 };
+                aml_append(ifctx2, aml_return(aml_buffer(2, byte_list)));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.1 Get Physical Presence Interface Version
+             *
+             * Arg 2 (Integer): Function Index = 1
+             * Arg 3 (Package): Arguments = Empty Package
+             * Returns: Type: String
+             */
+            ifctx2 = aml_if(aml_equal(function, one));
+            {
+                aml_append(ifctx2, aml_return(aml_string("1.3")));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.3 Submit TPM Operation Request to Pre-OS Environment
+             *
+             * Arg 2 (Integer): Function Index = 2
+             * Arg 3 (Package): Arguments = Package: Type: Integer
+             *                              Operation Value of the Request
+             * Returns: Type: Integer
+             *          0: Success
+             *          1: Operation Value of the Request Not Supported
+             *          2: General Failure
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(2)));
+            {
+                /* get opcode */
+                aml_append(ifctx2,
+                           aml_store(aml_derefof(aml_index(arguments,
+                                                           zero)), op));
+
+                /* get opcode flags */
+                aml_append(ifctx2,
+                           aml_store(aml_call1("TPFN", op), op_flags));
+
+                /* if func[opcode] & TPM_PPI_FUNC_NOT_IMPLEMENTED */
+                ifctx3 = aml_if(
+                    aml_equal(
+                        aml_and(op_flags, func_mask, NULL),
+                        not_implemented));
+                {
+                    /* 1: Operation Value of the Request Not Supported */
+                    aml_append(ifctx3, aml_return(one));
+                }
+                aml_append(ifctx2, ifctx3);
+
+                aml_append(ifctx2, aml_store(op, pprq));
+                aml_append(ifctx2, aml_store(zero, pprm));
+                /* 0: success */
+                aml_append(ifctx2, aml_return(zero));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.4 Get Pending TPM Operation Requested By the OS
+             *
+             * Arg 2 (Integer): Function Index = 3
+             * Arg 3 (Package): Arguments = Empty Package
+             * Returns: Type: Package of Integers
+             *          Integer 1: Function Return code
+             *                     0: Success
+             *                     1: General Failure
+             *          Integer 2: Pending operation requested by the OS
+             *                     0: None
+             *                    >0: Operation Value of the Pending Request
+             *          Integer 3: Optional argument to pending operation
+             *                     requested by the OS
+             *                     0: None
+             *                    >0: Argument Value of the Pending Request
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(3)));
+            {
+                /*
+                 * Revision ID of 1, no integer parameter beyond
+                 * parameter two are expected
+                 */
+                ifctx3 = aml_if(aml_equal(rev, one));
+                {
+                    /* TPM2[1] = PPRQ */
+                    aml_append(ifctx3,
+                               aml_store(pprq, aml_index(tpm2, one)));
+                    aml_append(ifctx3, aml_return(tpm2));
+                }
+                aml_append(ifctx2, ifctx3);
+
+                /*
+                 * A return value of {0, 23, 1} indicates that
+                 * operation 23 with argument 1 is pending.
+                 */
+                ifctx3 = aml_if(aml_equal(rev, aml_int(2)));
+                {
+                    /* TPM3[1] = PPRQ */
+                    aml_append(ifctx3,
+                               aml_store(pprq, aml_index(tpm3, one)));
+                    /* TPM3[2] = PPRM */
+                    aml_append(ifctx3,
+                               aml_store(pprm, aml_index(tpm3, aml_int(2))));
+                    aml_append(ifctx3, aml_return(tpm3));
+                }
+                aml_append(ifctx2, ifctx3);
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.5 Get Platform-Specific Action to Transition to
+             *     Pre-OS Environment
+             *
+             * Arg 2 (Integer): Function Index = 4
+             * Arg 3 (Package): Arguments = Empty Package
+             * Returns: Type: Integer
+             *          0: None
+             *          1: Shutdown
+             *          2: Reboot
+             *          3: OS Vendor-specific
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(4)));
+            {
+                /* reboot */
+                aml_append(ifctx2, aml_return(aml_int(2)));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.6 Return TPM Operation Response to OS Environment
+             *
+             * Arg 2 (Integer): Function Index = 5
+             * Arg 3 (Package): Arguments = Empty Package
+             * Returns: Type: Package of Integer
+             *          Integer 1: Function Return code
+             *                     0: Success
+             *                     1: General Failure
+             *          Integer 2: Most recent operation request
+             *                     0: None
+             *                    >0: Operation Value of the most recent request
+             *          Integer 3: Response to the most recent operation request
+             *                     0: Success
+             *                     0x00000001..0x00000FFF: Corresponding TPM
+             *                                             error code
+             *                     0xFFFFFFF0: User Abort or timeout of dialog
+             *                     0xFFFFFFF1: firmware Failure
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(5)));
+            {
+                /* TPM3[1] = LPPR */
+                aml_append(ifctx2,
+                           aml_store(aml_name("LPPR"),
+                                     aml_index(tpm3, one)));
+                /* TPM3[2] = PPRP */
+                aml_append(ifctx2,
+                           aml_store(aml_name("PPRP"),
+                                     aml_index(tpm3, aml_int(2))));
+                aml_append(ifctx2, aml_return(tpm3));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.0: 2.1.7 Submit preferred user language
+             *
+             * Arg 2 (Integer): Function Index = 6
+             * Arg 3 (Package): Arguments = String Package
+             *                  Preferred language code
+             * Returns: Type: Integer
+             * Function Return Code
+             *          3: Not implemented
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(6)));
+            {
+                /* 3 = not implemented */
+                aml_append(ifctx2, aml_return(aml_int(3)));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.1: 2.1.7 Submit TPM Operation Request to
+             *     Pre-OS Environment 2
+             *
+             * Arg 2 (Integer): Function Index = 7
+             * Arg 3 (Package): Arguments = Package: Type: Integer
+             *                  Integer 1: Operation Value of the Request
+             *                  Integer 2: Argument for Operation (optional)
+             * Returns: Type: Integer
+             *          0: Success
+             *          1: Not Implemented
+             *          2: General Failure
+             *          3: Operation blocked by current firmware settings
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(7)));
+            {
+                /* get opcode */
+                aml_append(ifctx2, aml_store(aml_derefof(aml_index(arguments,
+                                                                   zero)),
+                                             op));
+
+                /* get opcode flags */
+                aml_append(ifctx2, aml_store(aml_call1("TPFN", op),
+                                             op_flags));
+                /* if func[opcode] & TPM_PPI_FUNC_NOT_IMPLEMENTED */
+                ifctx3 = aml_if(
+                    aml_equal(
+                        aml_and(op_flags, func_mask, NULL),
+                        not_implemented));
+                {
+                    /* 1: not implemented */
+                    aml_append(ifctx3, aml_return(one));
+                }
+                aml_append(ifctx2, ifctx3);
+
+                /* if func[opcode] & TPM_PPI_FUNC_BLOCKED */
+                ifctx3 = aml_if(
+                    aml_equal(
+                        aml_and(op_flags, func_mask, NULL),
+                        aml_int(TPM_PPI_FUNC_BLOCKED)));
+                {
+                    /* 3: blocked by firmware */
+                    aml_append(ifctx3, aml_return(aml_int(3)));
+                }
+                aml_append(ifctx2, ifctx3);
+
+                /* revision to integer */
+                ifctx3 = aml_if(aml_equal(rev, one));
+                {
+                    /* revision 1 */
+                    /* PPRQ = op */
+                    aml_append(ifctx3, aml_store(op, pprq));
+                    /* no argument, PPRM = 0 */
+                    aml_append(ifctx3, aml_store(zero, pprm));
+                }
+                aml_append(ifctx2, ifctx3);
+
+                ifctx3 = aml_if(aml_equal(rev, aml_int(2)));
+                {
+                    /* revision 2 */
+                    /* PPRQ = op */
+                    op_arg = aml_derefof(aml_index(arguments, one));
+                    aml_append(ifctx3, aml_store(op, pprq));
+                    /* PPRM = arg3[1] */
+                    aml_append(ifctx3, aml_store(op_arg, pprm));
+                }
+                aml_append(ifctx2, ifctx3);
+                /* 0: success */
+                aml_append(ifctx2, aml_return(zero));
+            }
+            aml_append(ifctx, ifctx2);
+
+            /*
+             * PPI 1.1: 2.1.8 Get User Confirmation Status for Operation
+             *
+             * Arg 2 (Integer): Function Index = 8
+             * Arg 3 (Package): Arguments = Package: Type: Integer
+             *                  Operation Value that may need user confirmation
+             * Returns: Type: Integer
+             *          0: Not implemented
+             *          1: Firmware only
+             *          2: Blocked for OS by firmware configuration
+             *          3: Allowed and physically present user required
+             *          4: Allowed and physically present user not required
+             */
+            ifctx2 = aml_if(aml_equal(function, aml_int(8)));
+            {
+                /* get opcode */
+                aml_append(ifctx2,
+                           aml_store(aml_derefof(aml_index(arguments,
+                                                           zero)),
+                                     op));
+
+                /* get opcode flags */
+                aml_append(ifctx2, aml_store(aml_call1("TPFN", op),
+                                             op_flags));
+                /* return confirmation status code */
+                aml_append(ifctx2,
+                           aml_return(
+                               aml_and(op_flags, func_mask, NULL)));
+            }
+            aml_append(ifctx, ifctx2);
+
+            aml_append(ifctx, aml_return(aml_buffer(1, zerobyte)));
+        }
+        aml_append(method, ifctx);
+    }
+    aml_append(dev, method);
+}
+
 static void
 build_dsdt(GArray *table_data, BIOSLinker *linker,
            AcpiPmInfo *pm, AcpiMiscInfo *misc,
@@ -1802,6 +2183,7 @@  build_dsdt(GArray *table_data, BIOSLinker *linker,
     uint32_t nr_mem = machine->ram_slots;
     int root_bus_limit = 0xFF;
     PCIBus *bus = NULL;
+    TPMIf *tpm = tpm_find();
     int i;
 
     dsdt = init_aml_allocator();
@@ -2139,7 +2521,7 @@  build_dsdt(GArray *table_data, BIOSLinker *linker,
             /* Scan all PCI buses. Generate tables to support hotplug. */
             build_append_pci_bus_devices(scope, bus, pm->pcihp_bridge_en);
 
-            if (TPM_IS_TIS(tpm_find())) {
+            if (TPM_IS_TIS(tpm)) {
                 dev = aml_device("ISA.TPM");
                 aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0C31")));
                 aml_append(dev, aml_name_decl("_STA", aml_int(0xF)));
@@ -2153,6 +2535,9 @@  build_dsdt(GArray *table_data, BIOSLinker *linker,
                  */
                 /* aml_append(crs, aml_irq_no_flags(TPM_TIS_IRQ)); */
                 aml_append(dev, aml_name_decl("_CRS", crs));
+
+                build_tpm_ppi(tpm, dev);
+
                 aml_append(scope, dev);
             }
 
@@ -2160,7 +2545,7 @@  build_dsdt(GArray *table_data, BIOSLinker *linker,
         }
     }
 
-    if (TPM_IS_CRB(tpm_find())) {
+    if (TPM_IS_CRB(tpm)) {
         dev = aml_device("TPM");
         aml_append(dev, aml_name_decl("_HID", aml_string("MSFT0101")));
         crs = aml_resource_template();
@@ -2172,6 +2557,8 @@  build_dsdt(GArray *table_data, BIOSLinker *linker,
         aml_append(method, aml_return(aml_int(0x0f)));
         aml_append(dev, method);
 
+        build_tpm_ppi(tpm, dev);
+
         aml_append(sb_scope, dev);
     }
 
@@ -2924,7 +3311,7 @@  void acpi_setup(void)
         tpm_config = (FWCfgTPMConfig) {
             .tpmppi_address = cpu_to_le32(TPM_PPI_ADDR_BASE),
             .tpm_version = tpm_get_version(tpm_find()),
-            .tpmppi_version = TPM_PPI_VERSION_NONE
+            .tpmppi_version = TPM_PPI_VERSION_1_30
         };
         fw_cfg_add_file(pcms->fw_cfg, "etc/tpm/config",
                         &tpm_config, sizeof tpm_config);
diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt
index a5bdd5f26e..f3b7615161 100644
--- a/docs/specs/tpm.txt
+++ b/docs/specs/tpm.txt
@@ -62,6 +62,85 @@  URL:
 
 https://trustedcomputinggroup.org/tcg-acpi-specification/
 
+== ACPI PPI Interface ==
+
+QEMU supports the Physical Presence Interface (PPI) for TPM 1.2 and TPM 2. This
+interface requires ACPI and firmware support. The specification can be found at
+the following URL:
+
+https://trustedcomputinggroup.org/resource/tcg-physical-presence-interface-specification/
+
+PPI enables a system administrator (root) to request a modification to the
+TPM upon reboot. The PPI specification defines the operation requests and the
+actions the firmware has to take. The system administrator passes the operation
+request number to the firmware through an ACPI interface which writes this
+number to a memory location that the firmware knows. Upon reboot, the firmware
+finds the number and sends commands to the the TPM. The firmware writes the TPM
+result code and the operation request number to a memory location that ACPI can
+read from and pass the result on to the administrator.
+
+The PPI specification defines a set of mandatory and optional operations for
+the firmware to implement. The ACPI interface also allows an administrator to
+list the supported operations. In QEMU the ACPI code is generated by QEMU, yet
+the firmware needs to implement support on a per-operations basis, and
+different firmwares may support a different subset. Therefore, QEMU introduces
+the virtual memory device for PPI where the firmware can indicate which
+operations it supports and ACPI can enable the ones that are supported and
+disable all others. This interface lies in main memory and has the following
+layout:
+
+ +----------+--------+--------+-------------------------------------------+
+ |  Field   | Length | Offset | Description                               |
+ +----------+--------+--------+-------------------------------------------+
+ | func     |  0x100 |  0x000 | Firmware sets values for each supported   |
+ |          |        |        | operation. See defined values below.      |
+ +----------+--------+--------+-------------------------------------------+
+ | ppin     |   0x1  |  0x100 | SMI interrupt to use. Set by firmware.    |
+ |          |        |        | Not supported.                            |
+ +----------+--------+--------+-------------------------------------------+
+ | ppip     |   0x4  |  0x101 | ACPI function index to pass to SMM code.  |
+ |          |        |        | Set by ACPI. Not supported.               |
+ +----------+--------+--------+-------------------------------------------+
+ | pprp     |   0x4  |  0x105 | Result of last executed operation. Set by |
+ |          |        |        | firmware. See function index 5 for values.|
+ +----------+--------+--------+-------------------------------------------+
+ | pprq     |   0x4  |  0x109 | Operation request number to execute. See  |
+ |          |        |        | 'Physical Presence Interface Operation    |
+ |          |        |        | Summary' tables in specs. Set by ACPI.    |
+ +----------+--------+--------+-------------------------------------------+
+ | pprm     |   0x4  |  0x10d | Operation request optional parameter.     |
+ |          |        |        | Values depend on operation. Set by ACPI.  |
+ +----------+--------+--------+-------------------------------------------+
+ | lppr     |   0x4  |  0x111 | Last executed operation request number.   |
+ |          |        |        | Copied from pprq field by firmware.       |
+ +----------+--------+--------+-------------------------------------------+
+ | fret     |   0x4  |  0x115 | Result code from SMM function.            |
+ |          |        |        | Not supported.                            |
+ +----------+--------+--------+-------------------------------------------+
+ | res1     |  0x40  |  0x119 | Reserved for future use                   |
+ +----------+--------+--------+-------------------------------------------+
+ | next_step|   0x1  |  0x159 | Operation to execute after reboot by      |
+ |          |        |        | firmware. Used by firmware.               |
+ +----------+--------+--------+-------------------------------------------+
+
+   The following values are supported for the 'func' field. They correspond
+   to the values used by ACPI function index 8.
+
+ +----------+-------------------------------------------------------------+
+ | value    | Description                                                 |
+ +----------+-------------------------------------------------------------+
+ | 0        | Operation is not implemented.                               |
+ +----------+-------------------------------------------------------------+
+ | 1        | Operation is only accessible through firmware.              |
+ +----------+-------------------------------------------------------------+
+ | 2        | Operation is blocked for OS by firmware configuration.      |
+ +----------+-------------------------------------------------------------+
+ | 3        | Operation is allowed and physically present user required.  |
+ +----------+-------------------------------------------------------------+
+ | 4        | Operation is allowed and physically present user is not     |
+ |          | required.                                                   |
+ +----------+-------------------------------------------------------------+
+
 
 QEMU files related to TPM ACPI tables:
  - hw/i386/acpi-build.c