diff options
Diffstat (limited to 'debian/patches/bugfix/x86/x86-rfds-Mitigate-Register-File-Data-Sampling-RFDS.patch')
| -rw-r--r-- | debian/patches/bugfix/x86/x86-rfds-Mitigate-Register-File-Data-Sampling-RFDS.patch | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/debian/patches/bugfix/x86/x86-rfds-Mitigate-Register-File-Data-Sampling-RFDS.patch b/debian/patches/bugfix/x86/x86-rfds-Mitigate-Register-File-Data-Sampling-RFDS.patch new file mode 100644 index 0000000000..21603126c5 --- /dev/null +++ b/debian/patches/bugfix/x86/x86-rfds-Mitigate-Register-File-Data-Sampling-RFDS.patch @@ -0,0 +1,384 @@ +From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> +Date: Mon, 11 Mar 2024 12:29:43 -0700 +Subject: x86/rfds: Mitigate Register File Data Sampling (RFDS) +Origin: https://git.kernel.org/linus/8076fcde016c9c0e0660543e67bff86cb48a7c9c + +RFDS is a CPU vulnerability that may allow userspace to infer kernel +stale data previously used in floating point registers, vector registers +and integer registers. RFDS only affects certain Intel Atom processors. + +Intel released a microcode update that uses VERW instruction to clear +the affected CPU buffers. Unlike MDS, none of the affected cores support +SMT. + +Add RFDS bug infrastructure and enable the VERW based mitigation by +default, that clears the affected buffers just before exiting to +userspace. Also add sysfs reporting and cmdline parameter +"reg_file_data_sampling" to control the mitigation. + +For details see: +Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst + +Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> +Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> +Reviewed-by: Thomas Gleixner <tglx@linutronix.de> +Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> +--- + .../ABI/testing/sysfs-devices-system-cpu | 1 + + .../admin-guide/kernel-parameters.txt | 21 +++++ + arch/x86/Kconfig | 11 +++ + arch/x86/include/asm/cpufeatures.h | 1 + + arch/x86/include/asm/msr-index.h | 8 ++ + arch/x86/kernel/cpu/bugs.c | 78 ++++++++++++++++++- + arch/x86/kernel/cpu/common.c | 38 ++++++++- + drivers/base/cpu.c | 3 + + include/linux/cpu.h | 2 + + 9 files changed, 157 insertions(+), 6 deletions(-) + +diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu +index a1db6db47505..710d47be11e0 100644 +--- a/Documentation/ABI/testing/sysfs-devices-system-cpu ++++ b/Documentation/ABI/testing/sysfs-devices-system-cpu +@@ -516,6 +516,7 @@ What: /sys/devices/system/cpu/vulnerabilities + /sys/devices/system/cpu/vulnerabilities/mds + /sys/devices/system/cpu/vulnerabilities/meltdown + /sys/devices/system/cpu/vulnerabilities/mmio_stale_data ++ /sys/devices/system/cpu/vulnerabilities/reg_file_data_sampling + /sys/devices/system/cpu/vulnerabilities/retbleed + /sys/devices/system/cpu/vulnerabilities/spec_store_bypass + /sys/devices/system/cpu/vulnerabilities/spectre_v1 +diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt +index 31b3a25680d0..73062d47a462 100644 +--- a/Documentation/admin-guide/kernel-parameters.txt ++++ b/Documentation/admin-guide/kernel-parameters.txt +@@ -1150,6 +1150,26 @@ + The filter can be disabled or changed to another + driver later using sysfs. + ++ reg_file_data_sampling= ++ [X86] Controls mitigation for Register File Data ++ Sampling (RFDS) vulnerability. RFDS is a CPU ++ vulnerability which may allow userspace to infer ++ kernel data values previously stored in floating point ++ registers, vector registers, or integer registers. ++ RFDS only affects Intel Atom processors. ++ ++ on: Turns ON the mitigation. ++ off: Turns OFF the mitigation. ++ ++ This parameter overrides the compile time default set ++ by CONFIG_MITIGATION_RFDS. Mitigation cannot be ++ disabled when other VERW based mitigations (like MDS) ++ are enabled. In order to disable RFDS mitigation all ++ VERW based mitigations need to be disabled. ++ ++ For details see: ++ Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst ++ + driver_async_probe= [KNL] + List of driver names to be probed asynchronously. * + matches with all driver names. If * is specified, the +@@ -3398,6 +3418,7 @@ + nospectre_bhb [ARM64] + nospectre_v1 [X86,PPC] + nospectre_v2 [X86,PPC,S390,ARM64] ++ reg_file_data_sampling=off [X86] + retbleed=off [X86] + spec_store_bypass_disable=off [X86,PPC] + spectre_v2_user=off [X86] +diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig +index 5edec175b9bf..637e337c332e 100644 +--- a/arch/x86/Kconfig ++++ b/arch/x86/Kconfig +@@ -2614,6 +2614,17 @@ config GDS_FORCE_MITIGATION + + If in doubt, say N. + ++config MITIGATION_RFDS ++ bool "RFDS Mitigation" ++ depends on CPU_SUP_INTEL ++ default y ++ help ++ Enable mitigation for Register File Data Sampling (RFDS) by default. ++ RFDS is a hardware vulnerability which affects Intel Atom CPUs. It ++ allows unprivileged speculative access to stale data previously ++ stored in floating point, vector and integer registers. ++ See also <file:Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst> ++ + endif + + config ARCH_HAS_ADD_PAGES +diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h +index 2b62cdd8dd12..8511aad59581 100644 +--- a/arch/x86/include/asm/cpufeatures.h ++++ b/arch/x86/include/asm/cpufeatures.h +@@ -503,4 +503,5 @@ + /* BUG word 2 */ + #define X86_BUG_SRSO X86_BUG(1*32 + 0) /* AMD SRSO bug */ + #define X86_BUG_DIV0 X86_BUG(1*32 + 1) /* AMD DIV0 speculation bug */ ++#define X86_BUG_RFDS X86_BUG(1*32 + 2) /* CPU is vulnerable to Register File Data Sampling */ + #endif /* _ASM_X86_CPUFEATURES_H */ +diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h +index f1bd7b91b3c6..d1b5edaf6c34 100644 +--- a/arch/x86/include/asm/msr-index.h ++++ b/arch/x86/include/asm/msr-index.h +@@ -165,6 +165,14 @@ + * CPU is not vulnerable to Gather + * Data Sampling (GDS). + */ ++#define ARCH_CAP_RFDS_NO BIT(27) /* ++ * Not susceptible to Register ++ * File Data Sampling. ++ */ ++#define ARCH_CAP_RFDS_CLEAR BIT(28) /* ++ * VERW clears CPU Register ++ * File. ++ */ + + #define ARCH_CAP_XAPIC_DISABLE BIT(21) /* + * IA32_XAPIC_DISABLE_STATUS MSR +diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c +index cd6ac89c1a0d..01ac18f56147 100644 +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -480,6 +480,57 @@ static int __init mmio_stale_data_parse_cmdline(char *str) + } + early_param("mmio_stale_data", mmio_stale_data_parse_cmdline); + ++#undef pr_fmt ++#define pr_fmt(fmt) "Register File Data Sampling: " fmt ++ ++enum rfds_mitigations { ++ RFDS_MITIGATION_OFF, ++ RFDS_MITIGATION_VERW, ++ RFDS_MITIGATION_UCODE_NEEDED, ++}; ++ ++/* Default mitigation for Register File Data Sampling */ ++static enum rfds_mitigations rfds_mitigation __ro_after_init = ++ IS_ENABLED(CONFIG_MITIGATION_RFDS) ? RFDS_MITIGATION_VERW : RFDS_MITIGATION_OFF; ++ ++static const char * const rfds_strings[] = { ++ [RFDS_MITIGATION_OFF] = "Vulnerable", ++ [RFDS_MITIGATION_VERW] = "Mitigation: Clear Register File", ++ [RFDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", ++}; ++ ++static void __init rfds_select_mitigation(void) ++{ ++ if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) { ++ rfds_mitigation = RFDS_MITIGATION_OFF; ++ return; ++ } ++ if (rfds_mitigation == RFDS_MITIGATION_OFF) ++ return; ++ ++ if (x86_read_arch_cap_msr() & ARCH_CAP_RFDS_CLEAR) ++ setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); ++ else ++ rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED; ++} ++ ++static __init int rfds_parse_cmdline(char *str) ++{ ++ if (!str) ++ return -EINVAL; ++ ++ if (!boot_cpu_has_bug(X86_BUG_RFDS)) ++ return 0; ++ ++ if (!strcmp(str, "off")) ++ rfds_mitigation = RFDS_MITIGATION_OFF; ++ else if (!strcmp(str, "on")) ++ rfds_mitigation = RFDS_MITIGATION_VERW; ++ ++ return 0; ++} ++early_param("reg_file_data_sampling", rfds_parse_cmdline); ++ + #undef pr_fmt + #define pr_fmt(fmt) "" fmt + +@@ -513,6 +564,11 @@ static void __init md_clear_update_mitigation(void) + mmio_mitigation = MMIO_MITIGATION_VERW; + mmio_select_mitigation(); + } ++ if (rfds_mitigation == RFDS_MITIGATION_OFF && ++ boot_cpu_has_bug(X86_BUG_RFDS)) { ++ rfds_mitigation = RFDS_MITIGATION_VERW; ++ rfds_select_mitigation(); ++ } + out: + if (boot_cpu_has_bug(X86_BUG_MDS)) + pr_info("MDS: %s\n", mds_strings[mds_mitigation]); +@@ -522,6 +578,8 @@ static void __init md_clear_update_mitigation(void) + pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]); + else if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN)) + pr_info("MMIO Stale Data: Unknown: No mitigations\n"); ++ if (boot_cpu_has_bug(X86_BUG_RFDS)) ++ pr_info("Register File Data Sampling: %s\n", rfds_strings[rfds_mitigation]); + } + + static void __init md_clear_select_mitigation(void) +@@ -529,11 +587,12 @@ static void __init md_clear_select_mitigation(void) + mds_select_mitigation(); + taa_select_mitigation(); + mmio_select_mitigation(); ++ rfds_select_mitigation(); + + /* +- * As MDS, TAA and MMIO Stale Data mitigations are inter-related, update +- * and print their mitigation after MDS, TAA and MMIO Stale Data +- * mitigation selection is done. ++ * As these mitigations are inter-related and rely on VERW instruction ++ * to clear the microarchitural buffers, update and print their status ++ * after mitigation selection is done for each of these vulnerabilities. + */ + md_clear_update_mitigation(); + } +@@ -2622,6 +2681,11 @@ static ssize_t mmio_stale_data_show_state(char *buf) + sched_smt_active() ? "vulnerable" : "disabled"); + } + ++static ssize_t rfds_show_state(char *buf) ++{ ++ return sysfs_emit(buf, "%s\n", rfds_strings[rfds_mitigation]); ++} ++ + static char *stibp_state(void) + { + if (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && +@@ -2781,6 +2845,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr + case X86_BUG_GDS: + return gds_show_state(buf); + ++ case X86_BUG_RFDS: ++ return rfds_show_state(buf); ++ + default: + break; + } +@@ -2855,4 +2922,9 @@ ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *bu + { + return cpu_show_common(dev, attr, buf, X86_BUG_GDS); + } ++ ++ssize_t cpu_show_reg_file_data_sampling(struct device *dev, struct device_attribute *attr, char *buf) ++{ ++ return cpu_show_common(dev, attr, buf, X86_BUG_RFDS); ++} + #endif +diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c +index fbc4e60d027c..40d8c110bb32 100644 +--- a/arch/x86/kernel/cpu/common.c ++++ b/arch/x86/kernel/cpu/common.c +@@ -1267,6 +1267,8 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = { + #define SRSO BIT(5) + /* CPU is affected by GDS */ + #define GDS BIT(6) ++/* CPU is affected by Register File Data Sampling */ ++#define RFDS BIT(7) + + static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { + VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS), +@@ -1294,9 +1296,18 @@ static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { + VULNBL_INTEL_STEPPINGS(TIGERLAKE, X86_STEPPING_ANY, GDS), + VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED), + VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS), +- VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPING_ANY, MMIO | MMIO_SBDS), +- VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO), +- VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(ALDERLAKE, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(ALDERLAKE_L, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(RAPTORLAKE, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(RAPTORLAKE_P, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(RAPTORLAKE_S, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_GRACEMONT, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO | RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_GOLDMONT, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_GOLDMONT_D, X86_STEPPING_ANY, RFDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_GOLDMONT_PLUS, X86_STEPPING_ANY, RFDS), + + VULNBL_AMD(0x15, RETBLEED), + VULNBL_AMD(0x16, RETBLEED), +@@ -1330,6 +1341,24 @@ static bool arch_cap_mmio_immune(u64 ia32_cap) + ia32_cap & ARCH_CAP_SBDR_SSDP_NO); + } + ++static bool __init vulnerable_to_rfds(u64 ia32_cap) ++{ ++ /* The "immunity" bit trumps everything else: */ ++ if (ia32_cap & ARCH_CAP_RFDS_NO) ++ return false; ++ ++ /* ++ * VMMs set ARCH_CAP_RFDS_CLEAR for processors not in the blacklist to ++ * indicate that mitigation is needed because guest is running on a ++ * vulnerable hardware or may migrate to such hardware: ++ */ ++ if (ia32_cap & ARCH_CAP_RFDS_CLEAR) ++ return true; ++ ++ /* Only consult the blacklist when there is no enumeration: */ ++ return cpu_matches(cpu_vuln_blacklist, RFDS); ++} ++ + static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) + { + u64 ia32_cap = x86_read_arch_cap_msr(); +@@ -1441,6 +1470,9 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) + boot_cpu_has(X86_FEATURE_AVX)) + setup_force_cpu_bug(X86_BUG_GDS); + ++ if (vulnerable_to_rfds(ia32_cap)) ++ setup_force_cpu_bug(X86_BUG_RFDS); ++ + if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN)) + return; + +diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c +index 47de0f140ba6..0b33e81f9c9b 100644 +--- a/drivers/base/cpu.c ++++ b/drivers/base/cpu.c +@@ -588,6 +588,7 @@ CPU_SHOW_VULN_FALLBACK(mmio_stale_data); + CPU_SHOW_VULN_FALLBACK(retbleed); + CPU_SHOW_VULN_FALLBACK(spec_rstack_overflow); + CPU_SHOW_VULN_FALLBACK(gds); ++CPU_SHOW_VULN_FALLBACK(reg_file_data_sampling); + + static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); + static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); +@@ -602,6 +603,7 @@ static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL); + static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL); + static DEVICE_ATTR(spec_rstack_overflow, 0444, cpu_show_spec_rstack_overflow, NULL); + static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, NULL); ++static DEVICE_ATTR(reg_file_data_sampling, 0444, cpu_show_reg_file_data_sampling, NULL); + + static struct attribute *cpu_root_vulnerabilities_attrs[] = { + &dev_attr_meltdown.attr, +@@ -617,6 +619,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { + &dev_attr_retbleed.attr, + &dev_attr_spec_rstack_overflow.attr, + &dev_attr_gather_data_sampling.attr, ++ &dev_attr_reg_file_data_sampling.attr, + NULL + }; + +diff --git a/include/linux/cpu.h b/include/linux/cpu.h +index dcb89c987164..8654714421a0 100644 +--- a/include/linux/cpu.h ++++ b/include/linux/cpu.h +@@ -75,6 +75,8 @@ extern ssize_t cpu_show_spec_rstack_overflow(struct device *dev, + struct device_attribute *attr, char *buf); + extern ssize_t cpu_show_gds(struct device *dev, + struct device_attribute *attr, char *buf); ++extern ssize_t cpu_show_reg_file_data_sampling(struct device *dev, ++ struct device_attribute *attr, char *buf); + + extern __printf(4, 5) + struct device *cpu_device_create(struct device *parent, void *drvdata, +-- +2.43.0 + |