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/* SPDX-License-Identifier: GPL-2.0-only */
#include <arch/cpu.h>
#include <program_loading.h>
#include <commonlib/region.h>
#include <console/console.h>
#include <cpu/x86/mtrr.h>
/* For now this is a good lowest common denominator for the total CPU cache.
TODO: fetch the total amount of cache from CPUID leaf2. */
#define MAX_CPU_CACHE (256 * KiB)
/* This makes the 'worst' case assumption that all cachelines covered by
the MTRR, no matter the caching type, are filled and not overlapping. */
static uint32_t max_cache_used(void)
{
int i, total_mtrrs = get_var_mtrr_count();
uint32_t total_cache = 0;
for (i = 0; i < total_mtrrs; i++) {
msr_t mtrr = rdmsr(MTRR_PHYS_MASK(i));
if (!(mtrr.lo & MTRR_PHYS_MASK_VALID))
continue;
total_cache += ~(mtrr.lo & 0xfffff000) + 1;
}
return total_cache;
}
void platform_prog_run(struct prog *prog)
{
const uint32_t base = (uintptr_t)prog_start(prog);
const uint32_t size = prog_size(prog);
const uint32_t end = base + size;
const uint32_t cache_used = max_cache_used();
/* This will accumulate MTRR's as XIP stages are run.
For now this includes bootblock which sets ups its own
caching elsewhere, verstage and romstage */
int mtrr_num = get_free_var_mtrr();
uint32_t mtrr_base;
uint32_t mtrr_size = 4 * KiB;
struct cpuinfo_x86 cpu_info;
get_fms(&cpu_info, cpuid_eax(1));
/*
* An unidentified combination of speculative reads and branch
* predictions inside WRPROT-cacheable memory can cause invalidation
* of cachelines and loss of stack on models based on NetBurst
* microarchitecture. Therefore disable WRPROT region entirely for
* all family F models.
*/
if (cpu_info.x86 == 0xf) {
printk(BIOS_NOTICE,
"PROG_RUN: CPU does not support caching ROM\n"
"The next stage will run slowly!\n");
return;
}
if (mtrr_num == -1) {
printk(BIOS_NOTICE,
"PROG_RUN: No MTRR available to cache ROM!\n"
"The next stage will run slowly!\n");
return;
}
if (cache_used + mtrr_size > MAX_CPU_CACHE) {
printk(BIOS_NOTICE,
"PROG_RUN: No more cache available for the next stage\n"
"The next stage will run slowly!\n");
return;
}
while (1) {
if (ALIGN_DOWN(base, mtrr_size) + mtrr_size >= end)
break;
if (cache_used + mtrr_size * 2 > MAX_CPU_CACHE)
break;
mtrr_size *= 2;
}
mtrr_base = ALIGN_DOWN(base, mtrr_size);
if (mtrr_base + mtrr_size < end) {
printk(BIOS_NOTICE, "PROG_RUN: Limiting XIP cache to %uKiB!\n",
mtrr_size / KiB);
/* Check if we can cover a bigger range by aligning up. */
const uint32_t alt_base = ALIGN_UP(base, mtrr_size);
const uint32_t lower_coverage = mtrr_base + mtrr_size - base;
const uint32_t upper_coverage = MIN(alt_base + mtrr_size, end) - alt_base;
if (upper_coverage > lower_coverage)
mtrr_base = alt_base;
}
printk(BIOS_DEBUG,
"PROG_RUN: Setting MTRR to cache XIP stage. base: 0x%08x, size: 0x%08x\n",
mtrr_base, mtrr_size);
set_var_mtrr(mtrr_num, mtrr_base, mtrr_size, MTRR_TYPE_WRPROT);
}
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