Re: [Qemu-devel] [PATCH v2] Add ACPI tables for TPM

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

On Wed, Jul 30, 2014 at 10:54:20AM -0400, Stefan Berger wrote:
> On 07/30/2014 09:20 AM, Michael S. Tsirkin wrote:
> >On Tue, Jul 29, 2014 at 06:52:19AM -0400, Stefan Berger wrote:
> >>From: Stefan Berger <stefanb@linux.vnet.ibm.com>
> >>
> >>Add an SSDT ACPI table for the TPM device.
> >>Add a TCPA table for BIOS logging area when a TPM is being used.
> >>
> >>The latter follows this spec here:
> >>
> >>http://www.trustedcomputinggroup.org/files/static_page_files/DCD4188E-1A4B-B294-D050A155FB6F7385/TCG_ACPIGeneralSpecification_PublicReview.pdf
> >>
> >>Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> >>---
> >>  hw/i386/Makefile.objs |  3 ++-
> >>  hw/i386/acpi-build.c  | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> >>  hw/i386/acpi-defs.h   | 11 +++++++++++
> >>  hw/i386/ssdt-tpm.dsl  | 43 +++++++++++++++++++++++++++++++++++++++++++
> >>  hw/tpm/tpm_tis.h      |  5 +----
> >>  include/hw/acpi/tpm.h | 29 +++++++++++++++++++++++++++++
> >>  include/sysemu/tpm.h  |  5 +++++
> >>  7 files changed, 137 insertions(+), 5 deletions(-)
> >>  create mode 100644 hw/i386/ssdt-tpm.dsl
> >>  create mode 100644 include/hw/acpi/tpm.h
> >>
> >>diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
> >>index 48014ab..3688cf8 100644
> >>--- a/hw/i386/Makefile.objs
> >>+++ b/hw/i386/Makefile.objs
> >>@@ -10,7 +10,8 @@ obj-y += bios-linker-loader.o
> >>  hw/i386/acpi-build.o: hw/i386/acpi-build.c hw/i386/acpi-dsdt.hex \
> >>  	hw/i386/ssdt-proc.hex hw/i386/ssdt-pcihp.hex hw/i386/ssdt-misc.hex \
> >>  	hw/i386/acpi-dsdt.hex hw/i386/q35-acpi-dsdt.hex \
> >>-	hw/i386/q35-acpi-dsdt.hex hw/i386/ssdt-mem.hex
> >>+	hw/i386/q35-acpi-dsdt.hex hw/i386/ssdt-mem.hex \
> >>+	hw/i386/ssdt-tpm.hex
> >>  iasl-option=$(shell if test -z "`$(1) $(2) 2>&1 > /dev/null`" \
> >>      ; then echo "$(2)"; else echo "$(3)"; fi ;)
> >>diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >>index ebc5f03..d767e37 100644
> >>--- a/hw/i386/acpi-build.c
> >>+++ b/hw/i386/acpi-build.c
> >>@@ -38,6 +38,8 @@
> >>  #include "hw/loader.h"
> >>  #include "hw/isa/isa.h"
> >>  #include "hw/acpi/memory_hotplug.h"
> >>+#include "sysemu/tpm.h"
> >>+#include "hw/acpi/tpm.h"
> >>  /* Supported chipsets: */
> >>  #include "hw/acpi/piix4.h"
> >>@@ -75,6 +77,7 @@ typedef struct AcpiPmInfo {
> >>  typedef struct AcpiMiscInfo {
> >>      bool has_hpet;
> >>+    bool has_tpm;
> >>      DECLARE_BITMAP(slot_hotplug_enable, PCI_SLOT_MAX);
> >>      const unsigned char *dsdt_code;
> >>      unsigned dsdt_size;
> >>@@ -193,6 +196,7 @@ static void acpi_get_pm_info(AcpiPmInfo *pm)
> >>  static void acpi_get_misc_info(AcpiMiscInfo *info)
> >>  {
> >>      info->has_hpet = hpet_find();
> >>+    info->has_tpm = tpm_find();
> >>      info->pvpanic_port = pvpanic_port();
> >>  }
> >>@@ -681,6 +685,7 @@ static inline char acpi_get_hex(uint32_t val)
> >>  #include "hw/i386/ssdt-misc.hex"
> >>  #include "hw/i386/ssdt-pcihp.hex"
> >>+#include "hw/i386/ssdt-tpm.hex"
> >>  static void
> >>  build_append_notify_method(GArray *device, const char *name,
> >>@@ -1167,6 +1172,40 @@ build_hpet(GArray *table_data, GArray *linker)
> >>                   (void *)hpet, "HPET", sizeof(*hpet), 1);
> >>  }
> >>+static void
> >>+build_tpm_tcpa(GArray *table_data, GArray *linker)
> >>+{
> >>+    Acpi20Tcpa *tcpa;
> >>+    uint32_t log_area_minimum_length = TPM_LOG_AREA_MINIMUM_SIZE;
> >>+    uint64_t log_area_start_address;
> >>+    size_t len = log_area_minimum_length + sizeof(*tcpa);
> >>+
> >>+    log_area_start_address = table_data->len + sizeof(*tcpa);
> >>+
> >>+    tcpa = acpi_data_push(table_data, len);
> >>+
> >>+    tcpa->platform_class = cpu_to_le16(TPM_TCPA_ACPI_CLASS_CLIENT);
> >>+    tcpa->log_area_minimum_length = cpu_to_le32(log_area_minimum_length);
> >>+    tcpa->log_area_start_address = cpu_to_le64(log_area_start_address);
> >>+
> >>+    /* LASA address to be filled by Guest linker */
> >Hmm, you are simply allocating log area as part of the ACPI table.  It
> >works because bios happens to allocate tables from high memory.
> >But I think this is a problem in practice because
> >bios is allowed to allocate acpi memory differently.
> >On the other hand log presumably needs to reside in
> >physical memory somewhere.
> >
> >If you need bios to allocate this memory, then we will
> >need a new allocation type for this, add it to linker
> >in bios and qemu.
> 
> Why does the BIOS 'need' to allocate it? Why can it not just use the memory
> that QEMU allocates? Obviously I am using the 'pointer relocation' feature
> of the BIOS to bend the pointer in the TCPA table to this log area.

You tell me - your patches make BIOS allocate it.

> >
> >Alternatively, find some other way to get hold of
> >physical memory.
> >Is there a way to disable the log completely?
> >As defined in your patch, I doubt there's anything there, ever ..
> 
> There is currently no way to disable it. For a machine with a TPM, there
> should be support for an SSDT and this TCPA table for the BIOS to write logs
> into. So I allocate both and Linux for example can then show an empty table
> in /sys/kernel/security/tpm0/ascii_bios_measurements when the passthrough
> driver is used. I am working on a TPM driver for a CUSE TPM(CUSE = character
> device in user space) where we want the BIOS to behave exactly like the BIOS
> on real hardware and write its measurements into this log. I know at least
> that this then works the way it is implemented now.
> 
>    Stefan