From 3e42ee05d86c1de3ed23dddf08fd8e6451bdea92 Mon Sep 17 00:00:00 2001 From: Raul E Rangel Date: Mon, 27 Apr 2020 15:38:58 -0600 Subject: cpu/x86/mtrr/earlymtrr: Validate MTRR arguments The AMD64 Architecture Programmer's Manual, Volume 2: Systems Programming says the following about variable MTRRs: Variable Range Size and Alignment. The size and alignment of variable memory-ranges (MTRRs) and I/O ranges (IORRs) are restricted as follows: * The boundary on which a variable range is aligned must be equal to the range size. For example, a memory range of 16 Mbytes must be aligned on a 16-Mbyte boundary (i.e., naturally aligned). * The range size must be a power of 2 (2^n , 52 > n > 11), with a minimum allowable size of 4 Kbytes. For example, 4 Mbytes and 8 Mbytes are allowable memory range sizes, but 6 Mbytes is not allowable. Print out errors if these conditions are violated. I didn't assert since `set_var_mtrr` can be used in boot block before the serial console is enabled. BUG=b:147042464 TEST=Boot trembyle and see MTRR errors: MTRR Error: base 0xcc800000 must be aligned to size 0x1000000 Signed-off-by: Raul E Rangel Change-Id: I8b8c734c7599bd89cf9f212ed43c2dd5b2c8ba7b Reviewed-on: https://review.coreboot.org/c/coreboot/+/40762 Reviewed-by: Aaron Durbin Tested-by: build bot (Jenkins) --- src/cpu/x86/mtrr/earlymtrr.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'src/cpu') diff --git a/src/cpu/x86/mtrr/earlymtrr.c b/src/cpu/x86/mtrr/earlymtrr.c index e8608fd9cc..f96b05061f 100644 --- a/src/cpu/x86/mtrr/earlymtrr.c +++ b/src/cpu/x86/mtrr/earlymtrr.c @@ -4,6 +4,8 @@ #include #include #include +#include +#include /* Get first available variable MTRR. * Returns var# if available, else returns -1. @@ -34,6 +36,15 @@ void set_var_mtrr( /* Bit Bit 32-35 of MTRRphysMask should be set to 1 */ /* FIXME: It only support 4G less range */ msr_t basem, maskm; + + if (!IS_POWER_OF_2(size)) + printk(BIOS_ERR, "MTRR Error: size %#x is not a power of two\n", size); + if (size < 4 * KiB) + printk(BIOS_ERR, "MTRR Error: size %#x smaller than 4KiB\n", size); + if (base % size != 0) + printk(BIOS_ERR, "MTRR Error: base %#x must be aligned to size %#x\n", base, + size); + basem.lo = base | type; basem.hi = 0; wrmsr(MTRR_PHYS_BASE(reg), basem); -- cgit v1.2.3