Re: [Qemu-devel] [PATCH v3 2/4] acpi: add fw_cfg file for TPM and PPI virtual memory device

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 21 Jun 2018 12:10:32 +0200
Marc-André Lureau <marcandre.lureau@gmail.com> wrote:

> Hi
> 
> On Thu, Jun 21, 2018 at 12:00 PM, Igor Mammedov <imammedo@redhat.com> wrote:
> > On Tue, 15 May 2018 14:14:31 +0200
> > Marc-André Lureau <marcandre.lureau@redhat.com> wrote:
> >  
> >> From: Stefan Berger <stefanb@linux.vnet.ibm.com>
> >>
> >> To avoid having to hard code the base address of the PPI virtual
> >> memory device we introduce a fw_cfg file etc/tpm/config that holds the
> >> base address of the PPI device, the version of the PPI interface and
> >> the version of the attached TPM.  
> > is it related to TPM_PPI_ADDR_BASE added in previous patch?
> >  
> >>
> >> Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
> >> [ Marc-André: renamed to etc/tpm/config, made it static, document it ]
> >> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> >> ---
> >>  include/hw/acpi/tpm.h |  3 +++
> >>  hw/i386/acpi-build.c  | 17 +++++++++++++++++
> >>  docs/specs/tpm.txt    | 20 ++++++++++++++++++++
> >>  3 files changed, 40 insertions(+)
> >>
> >> diff --git a/include/hw/acpi/tpm.h b/include/hw/acpi/tpm.h
> >> index c082df7d1d..f79d68a77a 100644
> >> --- a/include/hw/acpi/tpm.h
> >> +++ b/include/hw/acpi/tpm.h
> >> @@ -193,4 +193,7 @@ REG32(CRB_DATA_BUFFER, 0x80)
> >>  #define TPM_PPI_ADDR_SIZE           0x400
> >>  #define TPM_PPI_ADDR_BASE           0xFED45000
> >>
> >> +#define TPM_PPI_VERSION_NONE        0
> >> +#define TPM_PPI_VERSION_1_30        1
> >> +
> >>  #endif /* HW_ACPI_TPM_H */
> >> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> >> index 9bc6d97ea1..f6d447f03a 100644
> >> --- a/hw/i386/acpi-build.c
> >> +++ b/hw/i386/acpi-build.c
> >> @@ -119,6 +119,12 @@ typedef struct AcpiBuildPciBusHotplugState {
> >>      bool pcihp_bridge_en;
> >>  } AcpiBuildPciBusHotplugState;
> >>
> >> +typedef struct FWCfgTPMConfig {
> >> +    uint32_t tpmppi_address;
> >> +    uint8_t tpm_version;
> >> +    uint8_t tpmppi_version;
> >> +} QEMU_PACKED FWCfgTPMConfig;
> >> +
> >>  static void init_common_fadt_data(Object *o, AcpiFadtData *data)
> >>  {
> >>      uint32_t io = object_property_get_uint(o, ACPI_PM_PROP_PM_IO_BASE, NULL);
> >> @@ -2873,6 +2879,7 @@ void acpi_setup(void)
> >>      AcpiBuildTables tables;
> >>      AcpiBuildState *build_state;
> >>      Object *vmgenid_dev;
> >> +    static FWCfgTPMConfig tpm_config;
> >>
> >>      if (!pcms->fw_cfg) {
> >>          ACPI_BUILD_DPRINTF("No fw cfg. Bailing out.\n");
> >> @@ -2907,6 +2914,16 @@ void acpi_setup(void)
> >>      fw_cfg_add_file(pcms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
> >>                      tables.tcpalog->data, acpi_data_len(tables.tcpalog));
> >>
> >> +    if (tpm_find()) {
> >> +        tpm_config = (FWCfgTPMConfig) {
> >> +            .tpmppi_address = cpu_to_le32(TPM_PPI_ADDR_BASE),
> >> +            .tpm_version = cpu_to_le32(tpm_get_version(tpm_find())),
> >> +            .tpmppi_version = cpu_to_le32(TPM_PPI_VERSION_NONE)
> >> +        };
> >> +        fw_cfg_add_file(pcms->fw_cfg, "etc/tpm/config",
> >> +                        &tpm_config, sizeof tpm_config);
> >> +    }  
> > why it's in ACPI part of the code, shouldn't it be a part of device,
> > could TPM be used without ACPI at all (-noacpi CLI option)?
> >
> > Wouldn't adding fwcfg entry unconditionally break migration?  
> 
> Because of unstable entry IDs? that could be problematic. (especially
> during boot time) What do you think Laszlo?
> 
> I guess we could have a "ppi" device property, that would imply having
> the etc/tpm/config fw_cfg entry. We would enable it by default in
> newer machine types (3.0?)
yep, something like this.
usual practice is to enable it by default and disable it for old
machine types using hw compat props (include/hw/compat.h)

> 
> >  
> >> +
> >>      vmgenid_dev = find_vmgenid_dev();
> >>      if (vmgenid_dev) {
> >>          vmgenid_add_fw_cfg(VMGENID(vmgenid_dev), pcms->fw_cfg,
> >> diff --git a/docs/specs/tpm.txt b/docs/specs/tpm.txt
> >> index c230c4c93e..2ddb768084 100644
> >> --- a/docs/specs/tpm.txt
> >> +++ b/docs/specs/tpm.txt
> >> @@ -20,6 +20,26 @@ QEMU files related to TPM TIS interface:
> >>   - hw/tpm/tpm_tis.h
> >>
> >>
> >> += fw_cfg interface =
> >> +
> >> +The bios/firmware may use the "etc/tpm/config" fw_cfg entry for
> >> +configuring the guest appropriately.
> >> +
> >> +The entry of 6 bytes has the following content, in little-endian:
> >> +
> >> +    #define TPM_VERSION_UNSPEC          0
> >> +    #define TPM_VERSION_1_2             1
> >> +    #define TPM_VERSION_2_0             2
> >> +
> >> +    #define TPM_PPI_VERSION_NONE        0
> >> +    #define TPM_PPI_VERSION_1_30        1
> >> +
> >> +    struct FWCfgTPMConfig {
> >> +        uint32_t tpmppi_address;         /* PPI memory location */
> >> +        uint8_t tpm_version;             /* TPM version */
> >> +        uint8_t tpmppi_version;          /* PPI version */
> >> +    };
> >> +
> >>  = ACPI Interface =
> >>
> >>  The TPM device is defined with ACPI ID "PNP0C31". QEMU builds a SSDT and passes  
> >
> >  
> 
> 
>