diff options
| -rw-r--r-- | src/security/intel/txt/getsec_enteraccs.S | 103 |
1 files changed, 86 insertions, 17 deletions
diff --git a/src/security/intel/txt/getsec_enteraccs.S b/src/security/intel/txt/getsec_enteraccs.S index 563dc08a15..be038b0607 100644 --- a/src/security/intel/txt/getsec_enteraccs.S +++ b/src/security/intel/txt/getsec_enteraccs.S @@ -108,10 +108,10 @@ cond_push_var_mtrrs: orl $(CR0_CD | CR0_NW), %eax movl %eax, %cr0 - /* Disable fixed MTRRs */ + /* Disable all MTRRs */ movl $(MTRR_DEF_TYPE_MSR), %ecx - rdmsr - andl $(~MTRR_DEF_TYPE_FIX_EN), %eax + xorl %eax, %eax + xorl %edx, %edx wrmsr /* @@ -165,24 +165,93 @@ cond_clear_var_mtrrs: * Chapter A.1.1 * Intel TXT Software Development Guide (Document: 315168-015) */ - movl $(MTRR_PHYS_BASE(0)), %ecx + + /* + * Important note: The MTRRs must cache less than a page (4 KiB) + * of unused memory after the BIOS ACM. Failure to do so will + * result in a TXT reset with Class Code 5, Major Error Code 2. + * + * The caller must have checked that there are enough variable + * MTRRs to cache the ACM size prior to invoking this routine. + */ + + /* Determine size of AC module */ movl 12(%ebp), %eax /* %eax = acmbase */ - orl $(6), %eax /* MTRR_TYPE_WB */ - movl $0, %edx + movl $1, %ebx + movl 16(%ebp), %ebx /* %ebx = acmsize */ + + /* Round up to page size */ + addl $(0xfff), %ebx + andl $(~0xfff), %ebx /* Aligned to a page (4 KiB) */ + + /* + * Use XMM to store local variables. This code will need to be + * used in romstage, and CAR will have been torn down by then. + */ + movd %eax, %xmm0 /* XMM0: Base address of next MTRR */ + movd %ebx, %xmm1 /* XMM1: Remaining size to cache */ + + /* Get the number of variable MTRRs */ + movl $(MTRR_CAP_MSR), %ecx + rdmsr + andl $(0xff), %eax + + /* Initialize ECX */ + movl $(MTRR_PHYS_BASE(0)), %ecx + + jmp cond_allocate_var_mtrrs + +body_allocate_var_mtrrs: + + /* Program MTRR base */ + xorl %edx, %edx + movd %xmm0, %eax + orl $(MTRR_TYPE_WRBACK), %eax wrmsr + incl %ecx /* Move index to MTRR_PHYS_MASK */ - /* Round acmsize to next power of two. Required for MTRR programming. */ - movl $1, %ebx - movl 16(%ebp), %ecx /* %ebx = acmsize */ - dec %ecx - bsr %ecx, %ecx /* find MSB */ - inc %ecx - shl %cl, %ebx - movl $(MTRR_PHYS_MASK(0)), %ecx - xorl %eax, %eax - subl %ebx, %eax /* %eax = 4GIB - log2_ceil(ACM SIZE) */ - orl $((1 << 11)), %eax /* MTRR_PHYS_MASK_VALID */ + /* Temporarily transfer MSR index to EDX so that CL can be used */ + movl %ecx, %edx + + /* Determine next size to cache */ + bsr %ebx, %ecx + movl $(1), %ebx + shl %cl, %ebx /* Can only use CL here */ + + /* Restore ECX */ + movl %edx, %ecx + + /* Update saved base address */ + addl %ebx, %eax + movd %eax, %xmm0 + + /* Update saved remaining size */ + movd %xmm1, %eax + subl %ebx, %eax + movd %eax, %xmm1 + + /* Program MTRR mask */ movl MTRR_HIGH_MASK, %edx + xorl %eax, %eax + subl %ebx, %eax /* %eax = 4GIB - size to cache */ + orl $(MTRR_PHYS_MASK_VALID), %eax + wrmsr + incl %ecx /* Move index to next MTRR_PHYS_BASE */ + +cond_allocate_var_mtrrs: + + /* Check if we still need to cache something */ + movd %xmm1, %ebx + andl %ebx, %ebx + + jnz body_allocate_var_mtrrs + + /* + * Now that the variable MTRRs have been set up, enable them. + */ + movl $(MTRR_DEF_TYPE_MSR), %ecx + rdmsr + orl $(MTRR_DEF_TYPE_EN), %eax wrmsr /* Enable cache - GPF# if not done */ |