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cpu/x86/smm: Refactor creating a stub/save state map 

This code was very hard to read so rewrite it using as few mutable local
variables as possible.

Tested on qemu with 128 cores.

Change-Id: I7a455ba45a1c92533a8ecfd1aeecf34b4a63e409
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63474
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@tutanota.com>
This commit is contained in:
Arthur Heymans 2022-04-07 19:14:48 +02:00 committed by Martin L Roth
parent 04860bb1e7
commit 0ab98d5ed3
1 changed files with 33 additions and 43 deletions
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76
src/cpu/x86/smm/smm_module_loader.c
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@ -1,5 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0-only */ /* SPDX-License-Identifier: GPL-2.0-only */
#include "assert.h"
#include <acpi/acpi_gnvs.h> #include <acpi/acpi_gnvs.h>
#include <stddef.h> #include <stddef.h>
#include <stdint.h> #include <stdint.h>
@ -85,65 +86,54 @@ struct cpu_smm_info cpus[CONFIG_MAX_CPUS] = { 0 };
* input : num_cpus in the system. The map will * input : num_cpus in the system. The map will
* be created from 0 to num_cpus. * be created from 0 to num_cpus.
*/ */
static int smm_create_map(uintptr_t smbase, unsigned int num_cpus, static int smm_create_map(const uintptr_t smbase, const unsigned int num_cpus,
const struct smm_loader_params *params) const struct smm_loader_params *params)
{ {
unsigned int i;
struct rmodule smm_stub; struct rmodule smm_stub;
unsigned int ss_size = params->per_cpu_save_state_size, stub_size;
unsigned int smm_entry_offset = SMM_ENTRY_OFFSET; if (ARRAY_SIZE(cpus) < num_cpus) {
unsigned int seg_count = 0, segments = 0, available; printk(BIOS_ERR, "%s: increase MAX_CPUS in Kconfig\n", __func__);
unsigned int cpus_in_segment = 0; return 0;
unsigned int base = smbase; }
if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) { if (rmodule_parse(&_binary_smmstub_start, &smm_stub)) {
printk(BIOS_ERR, "%s: unable to get SMM module size\n", __func__); printk(BIOS_ERR, "%s: unable to get SMM module size\n", __func__);
return 0; return 0;
} }
stub_size = rmodule_memory_size(&smm_stub); /*
/* How many CPUs can fit into one 64K segment? */ * How many CPUs can fit into one 64K segment?
available = 0xFFFF - smm_entry_offset - ss_size - stub_size; * Make sure that the first stub does not overlap with the last save state of a segment.
if (available > 0) { */
cpus_in_segment = available / ss_size; const size_t stub_size = rmodule_memory_size(&smm_stub);
/* minimum segments needed will always be 1 */ const size_t needed_ss_size = MAX(params->real_cpu_save_state_size, stub_size);
segments = num_cpus / cpus_in_segment + 1; const size_t cpus_per_segment =
printk(BIOS_DEBUG, (SMM_CODE_SEGMENT_SIZE - SMM_ENTRY_OFFSET - stub_size) / needed_ss_size;
"%s: cpus allowed in one segment %d\n", __func__, cpus_in_segment);
printk(BIOS_DEBUG, if (cpus_per_segment == 0) {
"%s: min # of segments needed %d\n", __func__, segments); printk(BIOS_ERR, "%s: CPUs won't fit in segment. Broken stub or save state size\n",
} else { __func__);
printk(BIOS_ERR, "%s: not enough space in SMM to setup all CPUs\n", __func__);
printk(BIOS_ERR, " save state & stub size need to be reduced\n");
printk(BIOS_ERR, " or increase SMRAM size\n");
return 0; return 0;
} }
if (ARRAY_SIZE(cpus) < num_cpus) { for (unsigned int i = 0; i < num_cpus; i++) {
printk(BIOS_ERR, if (i % cpus_per_segment == 0)
"%s: increase MAX_CPUS in Kconfig\n", __func__); printk(BIOS_DEBUG, "-------------NEW CODE SEGMENT --------------\n");
return 0;
}
for (i = 0; i < num_cpus; i++) {
printk(BIOS_DEBUG, "CPU 0x%x\n", i); printk(BIOS_DEBUG, "CPU 0x%x\n", i);
cpus[i].smbase = base; /* We copy the same stub for each CPU so they all need the same 'smbase'. */
cpus[i].entry = base + smm_entry_offset; const size_t segment_number = i / cpus_per_segment;
printk(BIOS_DEBUG, " smbase %lx entry %lx\n", cpus[i].smbase, cpus[i].smbase = smbase - SMM_CODE_SEGMENT_SIZE * segment_number
cpus[i].entry); - needed_ss_size * (i % cpus_per_segment);
cpus[i].ss_start = cpus[i].entry + (smm_entry_offset - ss_size); cpus[i].entry = cpus[i].smbase + SMM_ENTRY_OFFSET;
cpus[i].ss_start = cpus[i].smbase + SMM_CODE_SEGMENT_SIZE - needed_ss_size;
cpus[i].code_start = cpus[i].entry; cpus[i].code_start = cpus[i].entry;
cpus[i].code_end = cpus[i].entry + stub_size; cpus[i].code_end = cpus[i].entry + stub_size;
printk(BIOS_DEBUG, " ss_start %lx code_end %lx\n", cpus[i].ss_start, printk(BIOS_DEBUG, " Stub [0x%lx-0x%lx[\n", cpus[i].code_start,
cpus[i].code_end); cpus[i].code_end);
printk(BIOS_DEBUG, " Save state [0x%lx-0x%lx[\n",
cpus[i].ss_start + needed_ss_size - params->real_cpu_save_state_size,
cpus[i].ss_start + needed_ss_size);
cpus[i].active = 1; cpus[i].active = 1;
base -= ss_size;
seg_count++;
if (seg_count >= cpus_in_segment) {
base -= smm_entry_offset;
seg_count = 0;
printk(BIOS_DEBUG, "-------------NEW CODE SEGMENT --------------\n");
}
} }
return 1; return 1;