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xen.36362
xsa452-7.patch
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File xsa452-7.patch of Package xen.36362
From: Andrew Cooper <andrew.cooper3@citrix.com> Subject: x86/spec-ctrl: Mitigation Register File Data Sampling RFDS affects Atom cores, also branded E-cores, between the Goldmont and Gracemont microarchitectures. This includes Alder Lake and Raptor Lake hybrid clien systems which have a mix of Gracemont and other types of cores. Two new bits have been defined; RFDS_CLEAR to indicate VERW has more side effets, and RFDS_NO to incidate that the system is unaffected. Plenty of unaffected CPUs won't be getting RFDS_NO retrofitted in microcode, so we synthesise it. Alder Lake and Raptor Lake Xeon-E's are unaffected due to their platform configuration, and we must use the Hybrid CPUID bit to distinguish them from their non-Xeon counterparts. Like MD_CLEAR and FB_CLEAR, RFDS_CLEAR needs OR-ing across a resource pool, so set it in the max policies and reflect the host setting in default. This is part of XSA-452 / CVE-2023-28746. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com> (cherry picked from commit fb5b6f6744713410c74cfc12b7176c108e3c9a31) --- a/tools/misc/xen-cpuid.c +++ b/tools/misc/xen-cpuid.c @@ -169,7 +169,7 @@ static const char *const str_7d0[32] = /* 8 */ [ 9] = "srbds-ctrl", [10] = "md-clear", [11] = "rtm-always-abort", /* 12 */ [13] = "tsx-force-abort", - [14] = "serialize", + [14] = "serialize", [15] = "hybrid", [16] = "tsxldtrk", [18] = "pconfig", [20] = "cet-ibt", @@ -224,7 +224,8 @@ static const char *const str_m10Al[32] = [20] = "bhi-no", [21] = "xapic-status", /* 22 */ [23] = "ovrclk-status", [24] = "pbrsb-no", [25] = "gds-ctrl", - [26] = "gds-no", + [26] = "gds-no", [27] = "rfds-no", + [28] = "rfds-clear", }; static const char *const str_m10Ah[32] = --- a/xen/arch/x86/cpu-policy.c +++ b/xen/arch/x86/cpu-policy.c @@ -443,6 +443,7 @@ static void __init guest_common_max_feat */ __set_bit(X86_FEATURE_MD_CLEAR, fs); __set_bit(X86_FEATURE_FB_CLEAR, fs); + __set_bit(X86_FEATURE_RFDS_CLEAR, fs); /* * The Gather Data Sampling microcode mitigation (August 2023) has an @@ -492,6 +493,10 @@ static void __init guest_common_default_ if ( cpu_has_fb_clear ) __set_bit(X86_FEATURE_FB_CLEAR, fs); + __clear_bit(X86_FEATURE_RFDS_CLEAR, fs); + if ( cpu_has_rfds_clear ) + __set_bit(X86_FEATURE_RFDS_CLEAR, fs); + /* * The Gather Data Sampling microcode mitigation (August 2023) has an * adverse performance impact on the CLWB instruction on SKX/CLX/CPX. --- a/xen/arch/x86/spec_ctrl.c +++ b/xen/arch/x86/spec_ctrl.c @@ -432,7 +432,7 @@ static void __init print_details(enum in * Hardware read-only information, stating immunity to certain issues, or * suggestions of which mitigation to use. */ - printk(" Hardware hints:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", + printk(" Hardware hints:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", (caps & ARCH_CAPS_RDCL_NO) ? " RDCL_NO" : "", (caps & ARCH_CAPS_EIBRS) ? " EIBRS" : "", (caps & ARCH_CAPS_RSBA) ? " RSBA" : "", @@ -448,6 +448,7 @@ static void __init print_details(enum in (caps & ARCH_CAPS_FB_CLEAR) ? " FB_CLEAR" : "", (caps & ARCH_CAPS_PBRSB_NO) ? " PBRSB_NO" : "", (caps & ARCH_CAPS_GDS_NO) ? " GDS_NO" : "", + (caps & ARCH_CAPS_RFDS_NO) ? " RFDS_NO" : "", (e8b & cpufeat_mask(X86_FEATURE_IBRS_ALWAYS)) ? " IBRS_ALWAYS" : "", (e8b & cpufeat_mask(X86_FEATURE_STIBP_ALWAYS)) ? " STIBP_ALWAYS" : "", (e8b & cpufeat_mask(X86_FEATURE_IBRS_FAST)) ? " IBRS_FAST" : "", @@ -458,7 +459,7 @@ static void __init print_details(enum in (e21a & cpufeat_mask(X86_FEATURE_SRSO_NO)) ? " SRSO_NO" : ""); /* Hardware features which need driving to mitigate issues. */ - printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s\n", + printk(" Hardware features:%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n", (e8b & cpufeat_mask(X86_FEATURE_IBPB)) || (_7d0 & cpufeat_mask(X86_FEATURE_IBRSB)) ? " IBPB" : "", (e8b & cpufeat_mask(X86_FEATURE_IBRS)) || @@ -476,6 +477,7 @@ static void __init print_details(enum in (caps & ARCH_CAPS_TSX_CTRL) ? " TSX_CTRL" : "", (caps & ARCH_CAPS_FB_CLEAR_CTRL) ? " FB_CLEAR_CTRL" : "", (caps & ARCH_CAPS_GDS_CTRL) ? " GDS_CTRL" : "", + (caps & ARCH_CAPS_RFDS_CLEAR) ? " RFDS_CLEAR" : "", (e21a & cpufeat_mask(X86_FEATURE_SBPB)) ? " SBPB" : ""); /* Compiled-in support which pertains to mitigations. */ @@ -1295,6 +1297,83 @@ static __init void mds_calculations(void } } +/* + * Register File Data Sampling affects Atom cores from the Goldmont to + * Gracemont microarchitectures. The March 2024 microcode adds RFDS_NO to + * some but not all unaffected parts, and RFDS_CLEAR to affected parts still + * in support. + * + * Alder Lake and Raptor Lake client CPUs have a mix of P cores + * (Golden/Raptor Cove, not vulnerable) and E cores (Gracemont, + * vulnerable), and both enumerate RFDS_CLEAR. + * + * Both exist in a Xeon SKU, which has the E cores (Gracemont) disabled by + * platform configuration, and enumerate RFDS_NO. + * + * With older parts, or with out-of-date microcode, synthesise RFDS_NO when + * safe to do so. + * + * https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/register-file-data-sampling.html + */ +static void __init rfds_calculations(void) +{ + /* RFDS is only known to affect Intel Family 6 processors at this time. */ + if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL || + boot_cpu_data.x86 != 6 ) + return; + + /* + * If RFDS_NO or RFDS_CLEAR are visible, we've either got suitable + * microcode, or an RFDS-aware hypervisor is levelling us in a pool. + */ + if ( cpu_has_rfds_no || cpu_has_rfds_clear ) + return; + + /* If we're virtualised, don't attempt to synthesise RFDS_NO. */ + if ( cpu_has_hypervisor ) + return; + + /* + * Not all CPUs are expected to get a microcode update enumerating one of + * RFDS_{NO,CLEAR}, or we might have out-of-date microcode. + */ + switch ( boot_cpu_data.x86_model ) + { + case 0x97: /* INTEL_FAM6_ALDERLAKE */ + case 0xB7: /* INTEL_FAM6_RAPTORLAKE */ + /* + * Alder Lake and Raptor Lake might be a client SKU (with the + * Gracemont cores active, and therefore vulnerable) or might be a + * server SKU (with the Gracemont cores disabled, and therefore not + * vulnerable). + * + * See if the CPU identifies as hybrid to distinguish the two cases. + */ + if ( !cpu_has_hybrid ) + break; + /* fallthrough */ + case 0x9A: /* INTEL_FAM6_ALDERLAKE_L */ + case 0xBA: /* INTEL_FAM6_RAPTORLAKE_P */ + case 0xBF: /* INTEL_FAM6_RAPTORLAKE_S */ + + case 0x5C: /* INTEL_FAM6_ATOM_GOLDMONT */ /* Apollo Lake */ + case 0x5F: /* INTEL_FAM6_ATOM_GOLDMONT_D */ /* Denverton */ + case 0x7A: /* INTEL_FAM6_ATOM_GOLDMONT_PLUS */ /* Gemini Lake */ + case 0x86: /* INTEL_FAM6_ATOM_TREMONT_D */ /* Snow Ridge / Parker Ridge */ + case 0x96: /* INTEL_FAM6_ATOM_TREMONT */ /* Elkhart Lake */ + case 0x9C: /* INTEL_FAM6_ATOM_TREMONT_L */ /* Jasper Lake */ + case 0xBE: /* INTEL_FAM6_ATOM_GRACEMONT */ /* Alder Lake N */ + return; + } + + /* + * We appear to be on an unaffected CPU which didn't enumerate RFDS_NO, + * perhaps because of it's age or because of out-of-date microcode. + * Synthesise it. + */ + setup_force_cpu_cap(X86_FEATURE_RFDS_NO); +} + static bool __init cpu_has_gds(void) { /* @@ -1759,6 +1838,7 @@ void __init init_speculation_mitigations * * https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/intel-analysis-microarchitectural-data-sampling.html * https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/processor-mmio-stale-data-vulnerabilities.html + * https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/register-file-data-sampling.html * * Relevant ucodes: * @@ -1788,8 +1868,12 @@ void __init init_speculation_mitigations * * If FB_CLEAR is enumerated, L1D_FLUSH does not have the same scrubbing * side effects as VERW and cannot be used in its place. + * + * - March 2023, for RFDS. Enumerate RFDS_CLEAR to mean that VERW now + * scrubs non-architectural entries from certain register files. */ mds_calculations(); + rfds_calculations(); /* * Parts which enumerate FB_CLEAR are those with now-updated microcode @@ -1821,15 +1905,19 @@ void __init init_speculation_mitigations * MLPDS/MFBDS when SMT is enabled. */ if ( opt_verw_pv == -1 ) - opt_verw_pv = cpu_has_useful_md_clear; + opt_verw_pv = cpu_has_useful_md_clear || cpu_has_rfds_clear; if ( opt_verw_hvm == -1 ) - opt_verw_hvm = cpu_has_useful_md_clear; + opt_verw_hvm = cpu_has_useful_md_clear || cpu_has_rfds_clear; /* * If SMT is active, and we're protecting against MDS or MMIO stale data, * we need to scrub before going idle as well as on return to guest. * Various pipeline resources are repartitioned amongst non-idle threads. + * + * We don't need to scrub on idle for RFDS. There are no affected cores + * which support SMT, despite there being affected cores in hybrid systems + * which have SMT elsewhere in the platform. */ if ( ((cpu_has_useful_md_clear && (opt_verw_pv || opt_verw_hvm)) || opt_verw_mmio) && hw_smt_enabled ) @@ -1843,7 +1931,8 @@ void __init init_speculation_mitigations * It is only safe to use L1D_FLUSH in place of VERW when MD_CLEAR is the * only *_CLEAR we can see. */ - if ( opt_l1d_flush && cpu_has_md_clear && !cpu_has_fb_clear ) + if ( opt_l1d_flush && cpu_has_md_clear && !cpu_has_fb_clear && + !cpu_has_rfds_clear ) opt_verw_hvm = false; /* --- a/xen/include/asm-x86/cpufeature.h +++ b/xen/include/asm-x86/cpufeature.h @@ -138,6 +138,7 @@ #define cpu_has_rtm_always_abort boot_cpu_has(X86_FEATURE_RTM_ALWAYS_ABORT) #define cpu_has_tsx_force_abort boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT) #define cpu_has_serialize boot_cpu_has(X86_FEATURE_SERIALIZE) +#define cpu_has_hybrid boot_cpu_has(X86_FEATURE_HYBRID) #define cpu_has_arch_caps boot_cpu_has(X86_FEATURE_ARCH_CAPS) /* CPUID level 0x00000007:1.eax */ @@ -156,6 +157,8 @@ #define cpu_has_rrsba boot_cpu_has(X86_FEATURE_RRSBA) #define cpu_has_gds_ctrl boot_cpu_has(X86_FEATURE_GDS_CTRL) #define cpu_has_gds_no boot_cpu_has(X86_FEATURE_GDS_NO) +#define cpu_has_rfds_no boot_cpu_has(X86_FEATURE_RFDS_NO) +#define cpu_has_rfds_clear boot_cpu_has(X86_FEATURE_RFDS_CLEAR) /* Synthesized. */ #define cpu_has_arch_perfmon boot_cpu_has(X86_FEATURE_ARCH_PERFMON) --- a/xen/include/asm-x86/msr-index.h +++ b/xen/include/asm-x86/msr-index.h @@ -67,6 +67,8 @@ #define ARCH_CAPS_PBRSB_NO (_AC(1, ULL) << 24) #define ARCH_CAPS_GDS_CTRL (_AC(1, ULL) << 25) #define ARCH_CAPS_GDS_NO (_AC(1, ULL) << 26) +#define ARCH_CAPS_RFDS_NO (_AC(1, ULL) << 27) +#define ARCH_CAPS_RFDS_CLEAR (_AC(1, ULL) << 28) #define MSR_FLUSH_CMD 0x0000010b #define FLUSH_CMD_L1D (_AC(1, ULL) << 0) --- a/xen/include/public/arch-x86/cpufeatureset.h +++ b/xen/include/public/arch-x86/cpufeatureset.h @@ -275,6 +275,7 @@ XEN_CPUFEATURE(MD_CLEAR, 9*32+10) / XEN_CPUFEATURE(RTM_ALWAYS_ABORT, 9*32+11) /*! June 2021 TSX defeaturing in microcode. */ XEN_CPUFEATURE(TSX_FORCE_ABORT, 9*32+13) /* MSR_TSX_FORCE_ABORT.RTM_ABORT */ XEN_CPUFEATURE(SERIALIZE, 9*32+14) /*a SERIALIZE insn */ +XEN_CPUFEATURE(HYBRID, 9*32+15) /* Heterogeneous platform */ XEN_CPUFEATURE(TSXLDTRK, 9*32+16) /*a TSX load tracking suspend/resume insns */ XEN_CPUFEATURE(CET_IBT, 9*32+20) /* CET - Indirect Branch Tracking */ XEN_CPUFEATURE(IBRSB, 9*32+26) /*A IBRS and IBPB support (used by Intel) */ @@ -328,6 +329,8 @@ XEN_CPUFEATURE(OVRCLK_STATUS, 16*32 XEN_CPUFEATURE(PBRSB_NO, 16*32+24) /*A No Post-Barrier RSB predictions */ XEN_CPUFEATURE(GDS_CTRL, 16*32+25) /* MCU_OPT_CTRL.GDS_MIT_{DIS,LOCK} */ XEN_CPUFEATURE(GDS_NO, 16*32+26) /*A No Gather Data Sampling */ +XEN_CPUFEATURE(RFDS_NO, 16*32+27) /*A No Register File Data Sampling */ +XEN_CPUFEATURE(RFDS_CLEAR, 16*32+28) /*!A Register File(s) cleared by VERW */ /* Intel-defined CPU features, MSR_ARCH_CAPS 0x10a.edx, word 17 */
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