[PATCH] libacpi: Widen TPM detection

[Jason Andryuk <jandryuk@gmail.com>]

The hardcoded tpm_signature is too restrictive to detect many TPMs.  For
instance, it doesn't accept a QEMU emulated TPM (VID 0x1014 DID 0x0001).
Make the TPM detection match that in rombios which accepts a wider
range.

With this change, the TPM's TCPA ACPI table is generated and the guest
OS can automatically load the tpm_tis driver.  It also allows seabios to
detect and use the TPM.  However, seabios skips some TPM initialization
when running under Xen, so it will not populate any PCRs unless modified
to run the initialization under Xen.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
---
 tools/libacpi/build.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/tools/libacpi/build.c b/tools/libacpi/build.c
index fa7d14e090..a61dd5583a 100644
--- a/tools/libacpi/build.c
+++ b/tools/libacpi/build.c
@@ -351,7 +351,6 @@ static int construct_secondary_tables(struct acpi_ctxt *ctxt,
     struct acpi_20_waet *waet;
     struct acpi_20_tcpa *tcpa;
     unsigned char *ssdt;
-    static const uint16_t tis_signature[] = {0x0001, 0x0001, 0x0001};
     void *lasa;
 
     /* MADT. */
@@ -413,9 +412,8 @@ static int construct_secondary_tables(struct acpi_ctxt *ctxt,
 
     /* TPM TCPA and SSDT. */
     if ( (config->table_flags & ACPI_HAS_TCPA) &&
-         (config->tis_hdr[0] == tis_signature[0]) &&
-         (config->tis_hdr[1] == tis_signature[1]) &&
-         (config->tis_hdr[2] == tis_signature[2]) )
+         (config->tis_hdr[0] != 0 && config->tis_hdr[0] != 0xffff) &&
+         (config->tis_hdr[1] != 0 && config->tis_hdr[1] != 0xffff) )
     {
         ssdt = ctxt->mem_ops.alloc(ctxt, sizeof(ssdt_tpm), 16);
         if (!ssdt) return -1;
-- 
2.25.1