3 files changed, 123 insertions, 0 deletions
diff --git a/src/cpu/x86/Kconfig b/src/cpu/x86/Kconfig
index a8cf54d89e..b316c1ffc3 100644
--- a/src/cpu/x86/Kconfig
+++ b/src/cpu/x86/Kconfig
@@ -78,6 +78,16 @@ config XIP_ROM_SIZE
 	depends on !NO_FIXED_XIP_ROM_SIZE
 	default 0x10000
 
+config SETUP_XIP_CACHE
+	bool
+	depends on C_ENVIRONMENT_BOOTBLOCK
+	depends on !NO_XIP_EARLY_STAGES
+	help
+	  Select this option to set up an MTRR to cache XIP stages loaded
+	  from the bootblock. This is useful on platforms lacking a
+	  non-eviction mode and therefore need to be careful to avoid
+	  eviction.
+
 config CPU_ADDR_BITS
 	int
 	default 36
diff --git a/src/cpu/x86/mtrr/Makefile.inc b/src/cpu/x86/mtrr/Makefile.inc
index caa6e9c5d2..129d05d41b 100644
--- a/src/cpu/x86/mtrr/Makefile.inc
+++ b/src/cpu/x86/mtrr/Makefile.inc
@@ -2,8 +2,12 @@ ramstage-y	+= mtrr.c
 
 romstage-y	+= earlymtrr.c
 bootblock-y	+= earlymtrr.c
+verstage-y	+= earlymtrr.c
 
 bootblock-y	+= debug.c
 romstage-y	+= debug.c
 postcar-y	+= debug.c
 ramstage-y	+= debug.c
+
+bootblock-$(CONFIG_SETUP_XIP_CACHE) += xip_cache.c
+verstage-$(CONFIG_SETUP_XIP_CACHE) += xip_cache.c
diff --git a/src/cpu/x86/mtrr/xip_cache.c b/src/cpu/x86/mtrr/xip_cache.c
new file mode 100644
index 0000000000..112c0dfb90
--- /dev/null
+++ b/src/cpu/x86/mtrr/xip_cache.c
@@ -0,0 +1,109 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#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)
+{
+	msr_t msr = rdmsr(MTRR_CAP_MSR);
+	int i, total_mtrrs = msr.lo & MTRR_CAP_VCNT;
+	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 = region_device_offset(&prog->rdev);
+	const uint32_t size = region_device_sz(&prog->rdev);
+	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);
+}