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authorLinus Torvalds <torvalds@linux-foundation.org>2024-04-28 11:58:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2024-04-28 11:58:16 -0700
commitaec147c18856fa7115e14b9ad6a91c3ed2cf2e19 (patch)
tree842d91f32fba43cd3aba1fbb1f307302c63da866
parent8d62e9bf287588c839b67e567c8b2b548e849b00 (diff)
parentce0abef6a1d540acef85068e0e82bdf1fbeeb0e9 (diff)
Merge tag 'x86-urgent-2024-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar: - Make the CPU_MITIGATIONS=n interaction with conflicting mitigation-enabling boot parameters a bit saner. - Re-enable CPU mitigations by default on non-x86 - Fix TDX shared bit propagation on mprotect() - Fix potential show_regs() system hang when PKE initialization is not fully finished yet. - Add the 0x10-0x1f model IDs to the Zen5 range - Harden #VC instruction emulation some more * tag 'x86-urgent-2024-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n cpu: Re-enable CPU mitigations by default for !X86 architectures x86/tdx: Preserve shared bit on mprotect() x86/cpu: Fix check for RDPKRU in __show_regs() x86/CPU/AMD: Add models 0x10-0x1f to the Zen5 range x86/sev: Check for MWAITX and MONITORX opcodes in the #VC handler
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt3
-rw-r--r--arch/Kconfig8
-rw-r--r--arch/x86/Kconfig19
-rw-r--r--arch/x86/include/asm/coco.h1
-rw-r--r--arch/x86/include/asm/pgtable_types.h3
-rw-r--r--arch/x86/kernel/cpu/amd.c3
-rw-r--r--arch/x86/kernel/process_64.c2
-rw-r--r--arch/x86/kernel/sev-shared.c6
-rw-r--r--include/linux/cpu.h11
-rw-r--r--kernel/cpu.c14
10 files changed, 53 insertions, 17 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 902ecd92a29f..213d0719e2b7 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3423,6 +3423,9 @@
arch-independent options, each of which is an
aggregation of existing arch-specific options.
+ Note, "mitigations" is supported if and only if the
+ kernel was built with CPU_MITIGATIONS=y.
+
off
Disable all optional CPU mitigations. This
improves system performance, but it may also
diff --git a/arch/Kconfig b/arch/Kconfig
index 65afb1de48b3..30f7930275d8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -9,6 +9,14 @@
#
source "arch/$(SRCARCH)/Kconfig"
+config ARCH_CONFIGURES_CPU_MITIGATIONS
+ bool
+
+if !ARCH_CONFIGURES_CPU_MITIGATIONS
+config CPU_MITIGATIONS
+ def_bool y
+endif
+
menu "General architecture-dependent options"
config ARCH_HAS_SUBPAGE_FAULTS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4474bf32d0a4..928820e61cb5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -62,6 +62,7 @@ config X86
select ACPI_HOTPLUG_CPU if ACPI_PROCESSOR && HOTPLUG_CPU
select ARCH_32BIT_OFF_T if X86_32
select ARCH_CLOCKSOURCE_INIT
+ select ARCH_CONFIGURES_CPU_MITIGATIONS
select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
@@ -2488,17 +2489,21 @@ config PREFIX_SYMBOLS
def_bool y
depends on CALL_PADDING && !CFI_CLANG
-menuconfig SPECULATION_MITIGATIONS
- bool "Mitigations for speculative execution vulnerabilities"
+menuconfig CPU_MITIGATIONS
+ bool "Mitigations for CPU vulnerabilities"
default y
help
- Say Y here to enable options which enable mitigations for
- speculative execution hardware vulnerabilities.
+ Say Y here to enable options which enable mitigations for hardware
+ vulnerabilities (usually related to speculative execution).
+ Mitigations can be disabled or restricted to SMT systems at runtime
+ via the "mitigations" kernel parameter.
- If you say N, all mitigations will be disabled. You really
- should know what you are doing to say so.
+ If you say N, all mitigations will be disabled. This CANNOT be
+ overridden at runtime.
-if SPECULATION_MITIGATIONS
+ Say 'Y', unless you really know what you are doing.
+
+if CPU_MITIGATIONS
config MITIGATION_PAGE_TABLE_ISOLATION
bool "Remove the kernel mapping in user mode"
diff --git a/arch/x86/include/asm/coco.h b/arch/x86/include/asm/coco.h
index c086699b0d0c..aa6c8f8ca958 100644
--- a/arch/x86/include/asm/coco.h
+++ b/arch/x86/include/asm/coco.h
@@ -25,6 +25,7 @@ u64 cc_mkdec(u64 val);
void cc_random_init(void);
#else
#define cc_vendor (CC_VENDOR_NONE)
+static const u64 cc_mask = 0;
static inline u64 cc_mkenc(u64 val)
{
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index 0b748ee16b3d..9abb8cc4cd47 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -148,7 +148,7 @@
#define _COMMON_PAGE_CHG_MASK (PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT | \
_PAGE_SPECIAL | _PAGE_ACCESSED | \
_PAGE_DIRTY_BITS | _PAGE_SOFT_DIRTY | \
- _PAGE_DEVMAP | _PAGE_ENC | _PAGE_UFFD_WP)
+ _PAGE_DEVMAP | _PAGE_CC | _PAGE_UFFD_WP)
#define _PAGE_CHG_MASK (_COMMON_PAGE_CHG_MASK | _PAGE_PAT)
#define _HPAGE_CHG_MASK (_COMMON_PAGE_CHG_MASK | _PAGE_PSE | _PAGE_PAT_LARGE)
@@ -173,6 +173,7 @@ enum page_cache_mode {
};
#endif
+#define _PAGE_CC (_AT(pteval_t, cc_mask))
#define _PAGE_ENC (_AT(pteval_t, sme_me_mask))
#define _PAGE_CACHE_MASK (_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index cb9eece55904..307302af0aee 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -459,8 +459,7 @@ static void bsp_init_amd(struct cpuinfo_x86 *c)
case 0x1a:
switch (c->x86_model) {
- case 0x00 ... 0x0f:
- case 0x20 ... 0x2f:
+ case 0x00 ... 0x2f:
case 0x40 ... 0x4f:
case 0x70 ... 0x7f:
setup_force_cpu_cap(X86_FEATURE_ZEN5);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 7062b84dd467..6d3d20e3e43a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -139,7 +139,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode,
log_lvl, d3, d6, d7);
}
- if (cpu_feature_enabled(X86_FEATURE_OSPKE))
+ if (cr4 & X86_CR4_PKE)
printk("%sPKRU: %08x\n", log_lvl, read_pkru());
}
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index 8b04958da5e7..b4f8fa0f722c 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -1203,12 +1203,14 @@ static enum es_result vc_check_opcode_bytes(struct es_em_ctxt *ctxt,
break;
case SVM_EXIT_MONITOR:
- if (opcode == 0x010f && modrm == 0xc8)
+ /* MONITOR and MONITORX instructions generate the same error code */
+ if (opcode == 0x010f && (modrm == 0xc8 || modrm == 0xfa))
return ES_OK;
break;
case SVM_EXIT_MWAIT:
- if (opcode == 0x010f && modrm == 0xc9)
+ /* MWAIT and MWAITX instructions generate the same error code */
+ if (opcode == 0x010f && (modrm == 0xc9 || modrm == 0xfb))
return ES_OK;
break;
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 272e4e79e15c..861c3bfc5f17 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -221,7 +221,18 @@ void cpuhp_report_idle_dead(void);
static inline void cpuhp_report_idle_dead(void) { }
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
+#ifdef CONFIG_CPU_MITIGATIONS
extern bool cpu_mitigations_off(void);
extern bool cpu_mitigations_auto_nosmt(void);
+#else
+static inline bool cpu_mitigations_off(void)
+{
+ return true;
+}
+static inline bool cpu_mitigations_auto_nosmt(void)
+{
+ return false;
+}
+#endif
#endif /* _LINUX_CPU_H_ */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 07ad53b7f119..63447eb85dab 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3196,6 +3196,7 @@ void __init boot_cpu_hotplug_init(void)
this_cpu_write(cpuhp_state.target, CPUHP_ONLINE);
}
+#ifdef CONFIG_CPU_MITIGATIONS
/*
* These are used for a global "mitigations=" cmdline option for toggling
* optional CPU mitigations.
@@ -3206,9 +3207,7 @@ enum cpu_mitigations {
CPU_MITIGATIONS_AUTO_NOSMT,
};
-static enum cpu_mitigations cpu_mitigations __ro_after_init =
- IS_ENABLED(CONFIG_SPECULATION_MITIGATIONS) ? CPU_MITIGATIONS_AUTO :
- CPU_MITIGATIONS_OFF;
+static enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;
static int __init mitigations_parse_cmdline(char *arg)
{
@@ -3224,7 +3223,6 @@ static int __init mitigations_parse_cmdline(char *arg)
return 0;
}
-early_param("mitigations", mitigations_parse_cmdline);
/* mitigations=off */
bool cpu_mitigations_off(void)
@@ -3239,3 +3237,11 @@ bool cpu_mitigations_auto_nosmt(void)
return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
}
EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);
+#else
+static int __init mitigations_parse_cmdline(char *arg)
+{
+ pr_crit("Kernel compiled without mitigations, ignoring 'mitigations'; system may still be vulnerable\n");
+ return 0;
+}
+#endif
+early_param("mitigations", mitigations_parse_cmdline);