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361db0fca7
As we want to be able to disable VHE at runtime, let's match "id_aa64mmfr1.vh=" from the command line as an override. This doesn't have much effect yet as our boot code doesn't look at the cpufeature, but only at the HW registers. Signed-off-by: Marc Zyngier <maz@kernel.org> Acked-by: David Brazdil <dbrazdil@google.com> Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Link: https://lore.kernel.org/r/20210208095732.3267263-15-maz@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
162 lines
2.9 KiB
C
162 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Early cpufeature override framework
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*
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* Copyright (C) 2020 Google LLC
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* Author: Marc Zyngier <maz@kernel.org>
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*/
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#include <linux/ctype.h>
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#include <linux/kernel.h>
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#include <linux/libfdt.h>
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#include <asm/cacheflush.h>
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#include <asm/cpufeature.h>
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#include <asm/setup.h>
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#define FTR_DESC_NAME_LEN 20
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#define FTR_DESC_FIELD_LEN 10
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struct ftr_set_desc {
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char name[FTR_DESC_NAME_LEN];
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struct arm64_ftr_override *override;
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struct {
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char name[FTR_DESC_FIELD_LEN];
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u8 shift;
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} fields[];
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};
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static const struct ftr_set_desc mmfr1 __initconst = {
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.name = "id_aa64mmfr1",
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.override = &id_aa64mmfr1_override,
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.fields = {
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{ "vh", ID_AA64MMFR1_VHE_SHIFT },
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{}
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},
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};
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static const struct ftr_set_desc * const regs[] __initconst = {
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&mmfr1,
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};
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static int __init find_field(const char *cmdline,
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const struct ftr_set_desc *reg, int f, u64 *v)
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{
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char opt[FTR_DESC_NAME_LEN + FTR_DESC_FIELD_LEN + 2];
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int len;
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len = snprintf(opt, ARRAY_SIZE(opt), "%s.%s=",
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reg->name, reg->fields[f].name);
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if (!parameqn(cmdline, opt, len))
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return -1;
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return kstrtou64(cmdline + len, 0, v);
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}
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static void __init match_options(const char *cmdline)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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int f;
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if (!regs[i]->override)
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continue;
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for (f = 0; strlen(regs[i]->fields[f].name); f++) {
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u64 shift = regs[i]->fields[f].shift;
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u64 mask = 0xfUL << shift;
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u64 v;
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if (find_field(cmdline, regs[i], f, &v))
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continue;
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regs[i]->override->val &= ~mask;
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regs[i]->override->val |= (v << shift) & mask;
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regs[i]->override->mask |= mask;
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return;
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}
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}
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}
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static __init void __parse_cmdline(const char *cmdline)
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{
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do {
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char buf[256];
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size_t len;
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int i;
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cmdline = skip_spaces(cmdline);
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for (len = 0; cmdline[len] && !isspace(cmdline[len]); len++);
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if (!len)
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return;
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len = min(len, ARRAY_SIZE(buf) - 1);
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strncpy(buf, cmdline, len);
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buf[len] = 0;
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if (strcmp(buf, "--") == 0)
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return;
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cmdline += len;
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match_options(buf);
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} while (1);
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}
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static __init void parse_cmdline(void)
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{
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if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
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const u8 *prop;
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void *fdt;
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int node;
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fdt = get_early_fdt_ptr();
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if (!fdt)
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goto out;
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node = fdt_path_offset(fdt, "/chosen");
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if (node < 0)
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goto out;
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prop = fdt_getprop(fdt, node, "bootargs", NULL);
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if (!prop)
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goto out;
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__parse_cmdline(prop);
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if (!IS_ENABLED(CONFIG_CMDLINE_EXTEND))
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return;
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}
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out:
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__parse_cmdline(CONFIG_CMDLINE);
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}
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/* Keep checkers quiet */
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void init_feature_override(void);
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asmlinkage void __init init_feature_override(void)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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if (regs[i]->override) {
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regs[i]->override->val = 0;
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regs[i]->override->mask = 0;
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}
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}
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parse_cmdline();
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for (i = 0; i < ARRAY_SIZE(regs); i++) {
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if (regs[i]->override)
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__flush_dcache_area(regs[i]->override,
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sizeof(*regs[i]->override));
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}
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}
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