lib/fmap: Cache FMAP in cbmem

For platform independend exposure of FMAP through a kernel module
cache the FMAP in CBMEM. In addition add a pointer in coreboot tables
pointing to the introduced CBMEM area.

To not waste the allocated DRAM, use the cached CBMEM in RAM enabled
stages if possible.

Tested on qemu using
https://github.com/9elements/linux/commits/google_firmware_fmap2

Tested on QEMU and Supermicro X11SSH-TF.

Change-Id: I4e01c573c3edfa34dbba5fe7604d4f6e18b584d5
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35377
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Julius Werner <jwerner@chromium.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/src/lib/fmap.c b/src/lib/fmap.c
index 2b4e3bae2c..f0074186da 100644
--- a/src/lib/fmap.c
+++ b/src/lib/fmap.c
@@ -20,6 +20,7 @@
 #include <commonlib/fmap_serialized.h>
 #include <stddef.h>
 #include <string.h>
+#include <cbmem.h>
 
 #include "fmap_config.h"
 
@@ -28,6 +29,7 @@
  */
 
 static int fmap_print_once CAR_GLOBAL;
+static struct mem_region_device fmap_cache CAR_GLOBAL;
 
 int find_fmap_directory(struct region_device *fmrd)
 {
@@ -36,6 +38,16 @@ int find_fmap_directory(struct region_device *fmrd)
 	size_t fmap_size;
 	size_t offset = FMAP_OFFSET;
 
+	if (cbmem_possibly_online() && !ENV_SMM) {
+		/* Try FMAP cache first */
+		const struct mem_region_device *cache;
+
+		cache = car_get_var_ptr(&fmap_cache);
+		if (region_device_sz(&cache->rdev))
+			return rdev_chain(fmrd, &cache->rdev, 0,
+					  region_device_sz(&cache->rdev));
+	}
+
 	boot_device_init();
 	boot = boot_device_ro();
 
@@ -195,3 +207,53 @@ ssize_t fmap_overwrite_area(const char *name, const void *buffer, size_t size)
 		return -1;
 	return rdev_writeat(&rdev, buffer, 0, size);
 }
+
+static void fmap_register_cache(int unused)
+{
+	const struct cbmem_entry *e;
+	struct mem_region_device *mdev;
+
+	mdev = car_get_var_ptr(&fmap_cache);
+
+	/* Find the FMAP cache installed by previous stage */
+	e = cbmem_entry_find(CBMEM_ID_FMAP);
+	/* Don't set fmap_cache so that find_fmap_directory will use regular path */
+	if (!e)
+		return;
+
+	mem_region_device_ro_init(mdev, cbmem_entry_start(e), cbmem_entry_size(e));
+}
+
+/*
+ * The main reason to copy the FMAP into CBMEM is to make it available to the
+ * OS on every architecture. As side effect use the CBMEM copy as cache.
+ */
+static void fmap_setup_cache(int unused)
+{
+	struct region_device fmrd;
+
+	if (find_fmap_directory(&fmrd))
+		return;
+
+	/* Reloads the FMAP even on ACPI S3 resume */
+	const size_t s = region_device_sz(&fmrd);
+	struct fmap *fmap = cbmem_add(CBMEM_ID_FMAP, s);
+	if (!fmap) {
+		printk(BIOS_ERR, "ERROR: Failed to allocate CBMEM\n");
+		return;
+	}
+
+	const ssize_t ret = rdev_readat(&fmrd, fmap, 0, s);
+	if (ret != s) {
+		printk(BIOS_ERR, "ERROR: Failed to read FMAP into CBMEM\n");
+		cbmem_entry_remove(cbmem_entry_find(CBMEM_ID_FMAP));
+		return;
+	}
+
+	/* Finally advertise the cache for the current stage */
+	fmap_register_cache(unused);
+}
+
+ROMSTAGE_CBMEM_INIT_HOOK(fmap_setup_cache)
+RAMSTAGE_CBMEM_INIT_HOOK(fmap_register_cache)
+POSTCAR_CBMEM_INIT_HOOK(fmap_register_cache)