hvm: Improve tcgbios code for finding ACPI RSDP.

Signed-off-by: Stefan Berger <stefanb@us.ibm.com>

diff --git a/tools/firmware/rombios/32bit/tcgbios/tcgbios.c b/tools/firmware/rombios/32bit/tcgbios/tcgbios.c
index e4483982c43ac06a988ffd0189b6dd1175f44aff..c9b10f8327b4767b874639bc6a034e13910eb1b1 100644 (file)
--- a/tools/firmware/rombios/32bit/tcgbios/tcgbios.c
+++ b/tools/firmware/rombios/32bit/tcgbios/tcgbios.c
@@ -260,31 +260,44 @@ uint8_t acpi_validate_entry(struct acpi_header *hdr)
 }
 
 
+/*
+ * Search for the RSDP ACPI table in the memory starting at addr and
+ * ending at addr + len - 1.
+ */
+static struct acpi_20_rsdp *find_rsdp(const void *start, unsigned int len)
+{
+       char *rsdp = (char *)start;
+       char *end = rsdp + len;
+       /* scan memory in steps of 16 bytes */
+       while (rsdp < end) {
+               /* check for expected string */
+               if (!strncmp( rsdp, "RSD PTR ", 8))
+                       return (struct acpi_20_rsdp *)rsdp;
+               rsdp += 0x10;
+       }
+       return 0;
+}
+
 void tcpa_acpi_init(void)
 {
        struct acpi_20_rsdt *rsdt;
-       uint32_t length;
        struct acpi_20_tcpa *tcpa = (void *)0;
-       uint16_t found = 0;
-       uint16_t rsdp_off;
+       struct acpi_20_rsdp *rsdp;
+       uint32_t length;
        uint16_t off;
-       struct acpi_20_rsdp *rsdp = (void *)0;
+       int found = 0;
+       uint16_t ebda_seg;
 
        if (MA_IsTPMPresent() == 0) {
                return;
        }
 
-       /* scan memory in steps of  16 bytes in the ACPI_SEGMENT segment */
-       found = 0;
-       for (rsdp_off = 0; rsdp_off < 0xfff0; rsdp_off += 0x10) {
-               char *_rsdp = (char *)(ACPI_SEGMENT << 4);
-               /* check for expected string */
-               if (!strncmp( &_rsdp[rsdp_off], "RSD PTR ", 8)) {
-                       found = 1;
-                       rsdp = (struct acpi_20_rsdp *)&_rsdp[rsdp_off];
-                       break;
-               }
-       }
+       /* RSDP in EBDA? */
+       ebda_seg = *(uint16_t *)ADDR_FROM_SEG_OFF(0x40, 0xe);
+       rsdp = find_rsdp((void *)(ebda_seg << 16), 1024);
+
+       if (!rsdp)
+               rsdp = find_rsdp((void *)(ACPI_SEGMENT << 4), 0x20000);
 
        if (rsdp) {
                uint32_t ctr = 0;