diff options
| -rw-r--r-- | 0000_README | 4 | ||||
| -rw-r--r-- | 1004_linux-5.18.5.patch | 1113 |
2 files changed, 1117 insertions, 0 deletions
diff --git a/0000_README b/0000_README index 1dbd2f58..d6cb6557 100644 --- a/0000_README +++ b/0000_README @@ -59,6 +59,10 @@ Patch: 1003_linux-5.18.4.patch From: http://www.kernel.org Desc: Linux 5.18.4 +Patch: 1004_linux-5.18.5.patch +From: http://www.kernel.org +Desc: Linux 5.18.5 + Patch: 1500_XATTR_USER_PREFIX.patch From: https://bugs.gentoo.org/show_bug.cgi?id=470644 Desc: Support for namespace user.pax.* on tmpfs. diff --git a/1004_linux-5.18.5.patch b/1004_linux-5.18.5.patch new file mode 100644 index 00000000..88623faf --- /dev/null +++ b/1004_linux-5.18.5.patch @@ -0,0 +1,1113 @@ +diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu +index 2ad01cad7f1c8..bcc974d276dc4 100644 +--- a/Documentation/ABI/testing/sysfs-devices-system-cpu ++++ b/Documentation/ABI/testing/sysfs-devices-system-cpu +@@ -526,6 +526,7 @@ What: /sys/devices/system/cpu/vulnerabilities + /sys/devices/system/cpu/vulnerabilities/srbds + /sys/devices/system/cpu/vulnerabilities/tsx_async_abort + /sys/devices/system/cpu/vulnerabilities/itlb_multihit ++ /sys/devices/system/cpu/vulnerabilities/mmio_stale_data + Date: January 2018 + Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> + Description: Information about CPU vulnerabilities +diff --git a/Documentation/admin-guide/hw-vuln/index.rst b/Documentation/admin-guide/hw-vuln/index.rst +index 8cbc711cda935..4df436e7c4177 100644 +--- a/Documentation/admin-guide/hw-vuln/index.rst ++++ b/Documentation/admin-guide/hw-vuln/index.rst +@@ -17,3 +17,4 @@ are configurable at compile, boot or run time. + special-register-buffer-data-sampling.rst + core-scheduling.rst + l1d_flush.rst ++ processor_mmio_stale_data.rst +diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst +new file mode 100644 +index 0000000000000..9393c50b5afc9 +--- /dev/null ++++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst +@@ -0,0 +1,246 @@ ++========================================= ++Processor MMIO Stale Data Vulnerabilities ++========================================= ++ ++Processor MMIO Stale Data Vulnerabilities are a class of memory-mapped I/O ++(MMIO) vulnerabilities that can expose data. The sequences of operations for ++exposing data range from simple to very complex. Because most of the ++vulnerabilities require the attacker to have access to MMIO, many environments ++are not affected. System environments using virtualization where MMIO access is ++provided to untrusted guests may need mitigation. These vulnerabilities are ++not transient execution attacks. However, these vulnerabilities may propagate ++stale data into core fill buffers where the data can subsequently be inferred ++by an unmitigated transient execution attack. Mitigation for these ++vulnerabilities includes a combination of microcode update and software ++changes, depending on the platform and usage model. Some of these mitigations ++are similar to those used to mitigate Microarchitectural Data Sampling (MDS) or ++those used to mitigate Special Register Buffer Data Sampling (SRBDS). ++ ++Data Propagators ++================ ++Propagators are operations that result in stale data being copied or moved from ++one microarchitectural buffer or register to another. Processor MMIO Stale Data ++Vulnerabilities are operations that may result in stale data being directly ++read into an architectural, software-visible state or sampled from a buffer or ++register. ++ ++Fill Buffer Stale Data Propagator (FBSDP) ++----------------------------------------- ++Stale data may propagate from fill buffers (FB) into the non-coherent portion ++of the uncore on some non-coherent writes. Fill buffer propagation by itself ++does not make stale data architecturally visible. Stale data must be propagated ++to a location where it is subject to reading or sampling. ++ ++Sideband Stale Data Propagator (SSDP) ++------------------------------------- ++The sideband stale data propagator (SSDP) is limited to the client (including ++Intel Xeon server E3) uncore implementation. The sideband response buffer is ++shared by all client cores. For non-coherent reads that go to sideband ++destinations, the uncore logic returns 64 bytes of data to the core, including ++both requested data and unrequested stale data, from a transaction buffer and ++the sideband response buffer. As a result, stale data from the sideband ++response and transaction buffers may now reside in a core fill buffer. ++ ++Primary Stale Data Propagator (PSDP) ++------------------------------------ ++The primary stale data propagator (PSDP) is limited to the client (including ++Intel Xeon server E3) uncore implementation. Similar to the sideband response ++buffer, the primary response buffer is shared by all client cores. For some ++processors, MMIO primary reads will return 64 bytes of data to the core fill ++buffer including both requested data and unrequested stale data. This is ++similar to the sideband stale data propagator. ++ ++Vulnerabilities ++=============== ++Device Register Partial Write (DRPW) (CVE-2022-21166) ++----------------------------------------------------- ++Some endpoint MMIO registers incorrectly handle writes that are smaller than ++the register size. Instead of aborting the write or only copying the correct ++subset of bytes (for example, 2 bytes for a 2-byte write), more bytes than ++specified by the write transaction may be written to the register. On ++processors affected by FBSDP, this may expose stale data from the fill buffers ++of the core that created the write transaction. ++ ++Shared Buffers Data Sampling (SBDS) (CVE-2022-21125) ++---------------------------------------------------- ++After propagators may have moved data around the uncore and copied stale data ++into client core fill buffers, processors affected by MFBDS can leak data from ++the fill buffer. It is limited to the client (including Intel Xeon server E3) ++uncore implementation. ++ ++Shared Buffers Data Read (SBDR) (CVE-2022-21123) ++------------------------------------------------ ++It is similar to Shared Buffer Data Sampling (SBDS) except that the data is ++directly read into the architectural software-visible state. It is limited to ++the client (including Intel Xeon server E3) uncore implementation. ++ ++Affected Processors ++=================== ++Not all the CPUs are affected by all the variants. For instance, most ++processors for the server market (excluding Intel Xeon E3 processors) are ++impacted by only Device Register Partial Write (DRPW). ++ ++Below is the list of affected Intel processors [#f1]_: ++ ++ =================== ============ ========= ++ Common name Family_Model Steppings ++ =================== ============ ========= ++ HASWELL_X 06_3FH 2,4 ++ SKYLAKE_L 06_4EH 3 ++ BROADWELL_X 06_4FH All ++ SKYLAKE_X 06_55H 3,4,6,7,11 ++ BROADWELL_D 06_56H 3,4,5 ++ SKYLAKE 06_5EH 3 ++ ICELAKE_X 06_6AH 4,5,6 ++ ICELAKE_D 06_6CH 1 ++ ICELAKE_L 06_7EH 5 ++ ATOM_TREMONT_D 06_86H All ++ LAKEFIELD 06_8AH 1 ++ KABYLAKE_L 06_8EH 9 to 12 ++ ATOM_TREMONT 06_96H 1 ++ ATOM_TREMONT_L 06_9CH 0 ++ KABYLAKE 06_9EH 9 to 13 ++ COMETLAKE 06_A5H 2,3,5 ++ COMETLAKE_L 06_A6H 0,1 ++ ROCKETLAKE 06_A7H 1 ++ =================== ============ ========= ++ ++If a CPU is in the affected processor list, but not affected by a variant, it ++is indicated by new bits in MSR IA32_ARCH_CAPABILITIES. As described in a later ++section, mitigation largely remains the same for all the variants, i.e. to ++clear the CPU fill buffers via VERW instruction. ++ ++New bits in MSRs ++================ ++Newer processors and microcode update on existing affected processors added new ++bits to IA32_ARCH_CAPABILITIES MSR. These bits can be used to enumerate ++specific variants of Processor MMIO Stale Data vulnerabilities and mitigation ++capability. ++ ++MSR IA32_ARCH_CAPABILITIES ++-------------------------- ++Bit 13 - SBDR_SSDP_NO - When set, processor is not affected by either the ++ Shared Buffers Data Read (SBDR) vulnerability or the sideband stale ++ data propagator (SSDP). ++Bit 14 - FBSDP_NO - When set, processor is not affected by the Fill Buffer ++ Stale Data Propagator (FBSDP). ++Bit 15 - PSDP_NO - When set, processor is not affected by Primary Stale Data ++ Propagator (PSDP). ++Bit 17 - FB_CLEAR - When set, VERW instruction will overwrite CPU fill buffer ++ values as part of MD_CLEAR operations. Processors that do not ++ enumerate MDS_NO (meaning they are affected by MDS) but that do ++ enumerate support for both L1D_FLUSH and MD_CLEAR implicitly enumerate ++ FB_CLEAR as part of their MD_CLEAR support. ++Bit 18 - FB_CLEAR_CTRL - Processor supports read and write to MSR ++ IA32_MCU_OPT_CTRL[FB_CLEAR_DIS]. On such processors, the FB_CLEAR_DIS ++ bit can be set to cause the VERW instruction to not perform the ++ FB_CLEAR action. Not all processors that support FB_CLEAR will support ++ FB_CLEAR_CTRL. ++ ++MSR IA32_MCU_OPT_CTRL ++--------------------- ++Bit 3 - FB_CLEAR_DIS - When set, VERW instruction does not perform the FB_CLEAR ++action. This may be useful to reduce the performance impact of FB_CLEAR in ++cases where system software deems it warranted (for example, when performance ++is more critical, or the untrusted software has no MMIO access). Note that ++FB_CLEAR_DIS has no impact on enumeration (for example, it does not change ++FB_CLEAR or MD_CLEAR enumeration) and it may not be supported on all processors ++that enumerate FB_CLEAR. ++ ++Mitigation ++========== ++Like MDS, all variants of Processor MMIO Stale Data vulnerabilities have the ++same mitigation strategy to force the CPU to clear the affected buffers before ++an attacker can extract the secrets. ++ ++This is achieved by using the otherwise unused and obsolete VERW instruction in ++combination with a microcode update. The microcode clears the affected CPU ++buffers when the VERW instruction is executed. ++ ++Kernel reuses the MDS function to invoke the buffer clearing: ++ ++ mds_clear_cpu_buffers() ++ ++On MDS affected CPUs, the kernel already invokes CPU buffer clear on ++kernel/userspace, hypervisor/guest and C-state (idle) transitions. No ++additional mitigation is needed on such CPUs. ++ ++For CPUs not affected by MDS or TAA, mitigation is needed only for the attacker ++with MMIO capability. Therefore, VERW is not required for kernel/userspace. For ++virtualization case, VERW is only needed at VMENTER for a guest with MMIO ++capability. ++ ++Mitigation points ++----------------- ++Return to user space ++^^^^^^^^^^^^^^^^^^^^ ++Same mitigation as MDS when affected by MDS/TAA, otherwise no mitigation ++needed. ++ ++C-State transition ++^^^^^^^^^^^^^^^^^^ ++Control register writes by CPU during C-state transition can propagate data ++from fill buffer to uncore buffers. Execute VERW before C-state transition to ++clear CPU fill buffers. ++ ++Guest entry point ++^^^^^^^^^^^^^^^^^ ++Same mitigation as MDS when processor is also affected by MDS/TAA, otherwise ++execute VERW at VMENTER only for MMIO capable guests. On CPUs not affected by ++MDS/TAA, guest without MMIO access cannot extract secrets using Processor MMIO ++Stale Data vulnerabilities, so there is no need to execute VERW for such guests. ++ ++Mitigation control on the kernel command line ++--------------------------------------------- ++The kernel command line allows to control the Processor MMIO Stale Data ++mitigations at boot time with the option "mmio_stale_data=". The valid ++arguments for this option are: ++ ++ ========== ================================================================= ++ full If the CPU is vulnerable, enable mitigation; CPU buffer clearing ++ on exit to userspace and when entering a VM. Idle transitions are ++ protected as well. It does not automatically disable SMT. ++ full,nosmt Same as full, with SMT disabled on vulnerable CPUs. This is the ++ complete mitigation. ++ off Disables mitigation completely. ++ ========== ================================================================= ++ ++If the CPU is affected and mmio_stale_data=off is not supplied on the kernel ++command line, then the kernel selects the appropriate mitigation. ++ ++Mitigation status information ++----------------------------- ++The Linux kernel provides a sysfs interface to enumerate the current ++vulnerability status of the system: whether the system is vulnerable, and ++which mitigations are active. The relevant sysfs file is: ++ ++ /sys/devices/system/cpu/vulnerabilities/mmio_stale_data ++ ++The possible values in this file are: ++ ++ .. list-table:: ++ ++ * - 'Not affected' ++ - The processor is not vulnerable ++ * - 'Vulnerable' ++ - The processor is vulnerable, but no mitigation enabled ++ * - 'Vulnerable: Clear CPU buffers attempted, no microcode' ++ - The processor is vulnerable, but microcode is not updated. The ++ mitigation is enabled on a best effort basis. ++ * - 'Mitigation: Clear CPU buffers' ++ - The processor is vulnerable and the CPU buffer clearing mitigation is ++ enabled. ++ ++If the processor is vulnerable then the following information is appended to ++the above information: ++ ++ ======================== =========================================== ++ 'SMT vulnerable' SMT is enabled ++ 'SMT disabled' SMT is disabled ++ 'SMT Host state unknown' Kernel runs in a VM, Host SMT state unknown ++ ======================== =========================================== ++ ++References ++---------- ++.. [#f1] Affected Processors ++ https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html +diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt +index 3f1cc5e317ed4..c4893782055b4 100644 +--- a/Documentation/admin-guide/kernel-parameters.txt ++++ b/Documentation/admin-guide/kernel-parameters.txt +@@ -3105,6 +3105,7 @@ + kvm.nx_huge_pages=off [X86] + no_entry_flush [PPC] + no_uaccess_flush [PPC] ++ mmio_stale_data=off [X86] + + Exceptions: + This does not have any effect on +@@ -3126,6 +3127,7 @@ + Equivalent to: l1tf=flush,nosmt [X86] + mds=full,nosmt [X86] + tsx_async_abort=full,nosmt [X86] ++ mmio_stale_data=full,nosmt [X86] + + mminit_loglevel= + [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this +@@ -3135,6 +3137,40 @@ + log everything. Information is printed at KERN_DEBUG + so loglevel=8 may also need to be specified. + ++ mmio_stale_data= ++ [X86,INTEL] Control mitigation for the Processor ++ MMIO Stale Data vulnerabilities. ++ ++ Processor MMIO Stale Data is a class of ++ vulnerabilities that may expose data after an MMIO ++ operation. Exposed data could originate or end in ++ the same CPU buffers as affected by MDS and TAA. ++ Therefore, similar to MDS and TAA, the mitigation ++ is to clear the affected CPU buffers. ++ ++ This parameter controls the mitigation. The ++ options are: ++ ++ full - Enable mitigation on vulnerable CPUs ++ ++ full,nosmt - Enable mitigation and disable SMT on ++ vulnerable CPUs. ++ ++ off - Unconditionally disable mitigation ++ ++ On MDS or TAA affected machines, ++ mmio_stale_data=off can be prevented by an active ++ MDS or TAA mitigation as these vulnerabilities are ++ mitigated with the same mechanism so in order to ++ disable this mitigation, you need to specify ++ mds=off and tsx_async_abort=off too. ++ ++ Not specifying this option is equivalent to ++ mmio_stale_data=full. ++ ++ For details see: ++ Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst ++ + module.sig_enforce + [KNL] When CONFIG_MODULE_SIG is set, this means that + modules without (valid) signatures will fail to load. +diff --git a/Makefile b/Makefile +index 6cbf7bb15edde..34bfb76d63332 100644 +--- a/Makefile ++++ b/Makefile +@@ -1,7 +1,7 @@ + # SPDX-License-Identifier: GPL-2.0 + VERSION = 5 + PATCHLEVEL = 18 +-SUBLEVEL = 4 ++SUBLEVEL = 5 + EXTRAVERSION = + NAME = Superb Owl + +diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h +index 73e643ae94b6f..e17de69faa543 100644 +--- a/arch/x86/include/asm/cpufeatures.h ++++ b/arch/x86/include/asm/cpufeatures.h +@@ -443,5 +443,6 @@ + #define X86_BUG_TAA X86_BUG(22) /* CPU is affected by TSX Async Abort(TAA) */ + #define X86_BUG_ITLB_MULTIHIT X86_BUG(23) /* CPU may incur MCE during certain page attribute changes */ + #define X86_BUG_SRBDS X86_BUG(24) /* CPU may leak RNG bits if not mitigated */ ++#define X86_BUG_MMIO_STALE_DATA X86_BUG(25) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */ + + #endif /* _ASM_X86_CPUFEATURES_H */ +diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h +index ee15311b6be1d..4425d6773183b 100644 +--- a/arch/x86/include/asm/msr-index.h ++++ b/arch/x86/include/asm/msr-index.h +@@ -114,6 +114,30 @@ + * Not susceptible to + * TSX Async Abort (TAA) vulnerabilities. + */ ++#define ARCH_CAP_SBDR_SSDP_NO BIT(13) /* ++ * Not susceptible to SBDR and SSDP ++ * variants of Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_FBSDP_NO BIT(14) /* ++ * Not susceptible to FBSDP variant of ++ * Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_PSDP_NO BIT(15) /* ++ * Not susceptible to PSDP variant of ++ * Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_FB_CLEAR BIT(17) /* ++ * VERW clears CPU fill buffer ++ * even on MDS_NO CPUs. ++ */ ++#define ARCH_CAP_FB_CLEAR_CTRL BIT(18) /* ++ * MSR_IA32_MCU_OPT_CTRL[FB_CLEAR_DIS] ++ * bit available to control VERW ++ * behavior. ++ */ + + #define MSR_IA32_FLUSH_CMD 0x0000010b + #define L1D_FLUSH BIT(0) /* +@@ -131,6 +155,7 @@ + #define MSR_IA32_MCU_OPT_CTRL 0x00000123 + #define RNGDS_MITG_DIS BIT(0) /* SRBDS support */ + #define RTM_ALLOW BIT(1) /* TSX development mode */ ++#define FB_CLEAR_DIS BIT(3) /* CPU Fill buffer clear disable */ + + #define MSR_IA32_SYSENTER_CS 0x00000174 + #define MSR_IA32_SYSENTER_ESP 0x00000175 +diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h +index acbaeaf83b61a..da251a5645b0e 100644 +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -269,6 +269,8 @@ DECLARE_STATIC_KEY_FALSE(mds_idle_clear); + + DECLARE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush); + ++DECLARE_STATIC_KEY_FALSE(mmio_stale_data_clear); ++ + #include <asm/segment.h> + + /** +diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c +index 6296e1ebed1db..a8a9f64063315 100644 +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -41,8 +41,10 @@ static void __init spectre_v2_select_mitigation(void); + static void __init ssb_select_mitigation(void); + static void __init l1tf_select_mitigation(void); + static void __init mds_select_mitigation(void); +-static void __init mds_print_mitigation(void); ++static void __init md_clear_update_mitigation(void); ++static void __init md_clear_select_mitigation(void); + static void __init taa_select_mitigation(void); ++static void __init mmio_select_mitigation(void); + static void __init srbds_select_mitigation(void); + static void __init l1d_flush_select_mitigation(void); + +@@ -85,6 +87,10 @@ EXPORT_SYMBOL_GPL(mds_idle_clear); + */ + DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush); + ++/* Controls CPU Fill buffer clear before KVM guest MMIO accesses */ ++DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear); ++EXPORT_SYMBOL_GPL(mmio_stale_data_clear); ++ + void __init check_bugs(void) + { + identify_boot_cpu(); +@@ -117,17 +123,10 @@ void __init check_bugs(void) + spectre_v2_select_mitigation(); + ssb_select_mitigation(); + l1tf_select_mitigation(); +- mds_select_mitigation(); +- taa_select_mitigation(); ++ md_clear_select_mitigation(); + srbds_select_mitigation(); + l1d_flush_select_mitigation(); + +- /* +- * As MDS and TAA mitigations are inter-related, print MDS +- * mitigation until after TAA mitigation selection is done. +- */ +- mds_print_mitigation(); +- + arch_smt_update(); + + #ifdef CONFIG_X86_32 +@@ -267,14 +266,6 @@ static void __init mds_select_mitigation(void) + } + } + +-static void __init mds_print_mitigation(void) +-{ +- if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) +- return; +- +- pr_info("%s\n", mds_strings[mds_mitigation]); +-} +- + static int __init mds_cmdline(char *str) + { + if (!boot_cpu_has_bug(X86_BUG_MDS)) +@@ -329,7 +320,7 @@ static void __init taa_select_mitigation(void) + /* TSX previously disabled by tsx=off */ + if (!boot_cpu_has(X86_FEATURE_RTM)) { + taa_mitigation = TAA_MITIGATION_TSX_DISABLED; +- goto out; ++ return; + } + + if (cpu_mitigations_off()) { +@@ -343,7 +334,7 @@ static void __init taa_select_mitigation(void) + */ + if (taa_mitigation == TAA_MITIGATION_OFF && + mds_mitigation == MDS_MITIGATION_OFF) +- goto out; ++ return; + + if (boot_cpu_has(X86_FEATURE_MD_CLEAR)) + taa_mitigation = TAA_MITIGATION_VERW; +@@ -375,18 +366,6 @@ static void __init taa_select_mitigation(void) + + if (taa_nosmt || cpu_mitigations_auto_nosmt()) + cpu_smt_disable(false); +- +- /* +- * Update MDS mitigation, if necessary, as the mds_user_clear is +- * now enabled for TAA mitigation. +- */ +- if (mds_mitigation == MDS_MITIGATION_OFF && +- boot_cpu_has_bug(X86_BUG_MDS)) { +- mds_mitigation = MDS_MITIGATION_FULL; +- mds_select_mitigation(); +- } +-out: +- pr_info("%s\n", taa_strings[taa_mitigation]); + } + + static int __init tsx_async_abort_parse_cmdline(char *str) +@@ -410,6 +389,151 @@ static int __init tsx_async_abort_parse_cmdline(char *str) + } + early_param("tsx_async_abort", tsx_async_abort_parse_cmdline); + ++#undef pr_fmt ++#define pr_fmt(fmt) "MMIO Stale Data: " fmt ++ ++enum mmio_mitigations { ++ MMIO_MITIGATION_OFF, ++ MMIO_MITIGATION_UCODE_NEEDED, ++ MMIO_MITIGATION_VERW, ++}; ++ ++/* Default mitigation for Processor MMIO Stale Data vulnerabilities */ ++static enum mmio_mitigations mmio_mitigation __ro_after_init = MMIO_MITIGATION_VERW; ++static bool mmio_nosmt __ro_after_init = false; ++ ++static const char * const mmio_strings[] = { ++ [MMIO_MITIGATION_OFF] = "Vulnerable", ++ [MMIO_MITIGATION_UCODE_NEEDED] = "Vulnerable: Clear CPU buffers attempted, no microcode", ++ [MMIO_MITIGATION_VERW] = "Mitigation: Clear CPU buffers", ++}; ++ ++static void __init mmio_select_mitigation(void) ++{ ++ u64 ia32_cap; ++ ++ if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || ++ cpu_mitigations_off()) { ++ mmio_mitigation = MMIO_MITIGATION_OFF; ++ return; ++ } ++ ++ if (mmio_mitigation == MMIO_MITIGATION_OFF) ++ return; ++ ++ ia32_cap = x86_read_arch_cap_msr(); ++ ++ /* ++ * Enable CPU buffer clear mitigation for host and VMM, if also affected ++ * by MDS or TAA. Otherwise, enable mitigation for VMM only. ++ */ ++ if (boot_cpu_has_bug(X86_BUG_MDS) || (boot_cpu_has_bug(X86_BUG_TAA) && ++ boot_cpu_has(X86_FEATURE_RTM))) ++ static_branch_enable(&mds_user_clear); ++ else ++ static_branch_enable(&mmio_stale_data_clear); ++ ++ /* ++ * If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can ++ * be propagated to uncore buffers, clearing the Fill buffers on idle ++ * is required irrespective of SMT state. ++ */ ++ if (!(ia32_cap & ARCH_CAP_FBSDP_NO)) ++ static_branch_enable(&mds_idle_clear); ++ ++ /* ++ * Check if the system has the right microcode. ++ * ++ * CPU Fill buffer clear mitigation is enumerated by either an explicit ++ * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS ++ * affected systems. ++ */ ++ if ((ia32_cap & ARCH_CAP_FB_CLEAR) || ++ (boot_cpu_has(X86_FEATURE_MD_CLEAR) && ++ boot_cpu_has(X86_FEATURE_FLUSH_L1D) && ++ !(ia32_cap & ARCH_CAP_MDS_NO))) ++ mmio_mitigation = MMIO_MITIGATION_VERW; ++ else ++ mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED; ++ ++ if (mmio_nosmt || cpu_mitigations_auto_nosmt()) ++ cpu_smt_disable(false); ++} ++ ++static int __init mmio_stale_data_parse_cmdline(char *str) ++{ ++ if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) ++ return 0; ++ ++ if (!str) ++ return -EINVAL; ++ ++ if (!strcmp(str, "off")) { ++ mmio_mitigation = MMIO_MITIGATION_OFF; ++ } else if (!strcmp(str, "full")) { ++ mmio_mitigation = MMIO_MITIGATION_VERW; ++ } else if (!strcmp(str, "full,nosmt")) { ++ mmio_mitigation = MMIO_MITIGATION_VERW; ++ mmio_nosmt = true; ++ } ++ ++ return 0; ++} ++early_param("mmio_stale_data", mmio_stale_data_parse_cmdline); ++ ++#undef pr_fmt ++#define pr_fmt(fmt) "" fmt ++ ++static void __init md_clear_update_mitigation(void) ++{ ++ if (cpu_mitigations_off()) ++ return; ++ ++ if (!static_key_enabled(&mds_user_clear)) ++ goto out; ++ ++ /* ++ * mds_user_clear is now enabled. Update MDS, TAA and MMIO Stale Data ++ * mitigation, if necessary. ++ */ ++ if (mds_mitigation == MDS_MITIGATION_OFF && ++ boot_cpu_has_bug(X86_BUG_MDS)) { ++ mds_mitigation = MDS_MITIGATION_FULL; ++ mds_select_mitigation(); ++ } ++ if (taa_mitigation == TAA_MITIGATION_OFF && ++ boot_cpu_has_bug(X86_BUG_TAA)) { ++ taa_mitigation = TAA_MITIGATION_VERW; ++ taa_select_mitigation(); ++ } ++ if (mmio_mitigation == MMIO_MITIGATION_OFF && ++ boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) { ++ mmio_mitigation = MMIO_MITIGATION_VERW; ++ mmio_select_mitigation(); ++ } ++out: ++ if (boot_cpu_has_bug(X86_BUG_MDS)) ++ pr_info("MDS: %s\n", mds_strings[mds_mitigation]); ++ if (boot_cpu_has_bug(X86_BUG_TAA)) ++ pr_info("TAA: %s\n", taa_strings[taa_mitigation]); ++ if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) ++ pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]); ++} ++ ++static void __init md_clear_select_mitigation(void) ++{ ++ mds_select_mitigation(); ++ taa_select_mitigation(); ++ mmio_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. ++ */ ++ md_clear_update_mitigation(); ++} ++ + #undef pr_fmt + #define pr_fmt(fmt) "SRBDS: " fmt + +@@ -471,11 +595,13 @@ static void __init srbds_select_mitigation(void) + return; + + /* +- * Check to see if this is one of the MDS_NO systems supporting +- * TSX that are only exposed to SRBDS when TSX is enabled. ++ * Check to see if this is one of the MDS_NO systems supporting TSX that ++ * are only exposed to SRBDS when TSX is enabled or when CPU is affected ++ * by Processor MMIO Stale Data vulnerability. + */ + ia32_cap = x86_read_arch_cap_msr(); +- if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM)) ++ if ((ia32_cap & ARCH_CAP_MDS_NO) && !boot_cpu_has(X86_FEATURE_RTM) && ++ !boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) + srbds_mitigation = SRBDS_MITIGATION_TSX_OFF; + else if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) + srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR; +@@ -1109,6 +1235,8 @@ static void update_indir_branch_cond(void) + /* Update the static key controlling the MDS CPU buffer clear in idle */ + static void update_mds_branch_idle(void) + { ++ u64 ia32_cap = x86_read_arch_cap_msr(); ++ + /* + * Enable the idle clearing if SMT is active on CPUs which are + * affected only by MSBDS and not any other MDS variant. +@@ -1120,14 +1248,17 @@ static void update_mds_branch_idle(void) + if (!boot_cpu_has_bug(X86_BUG_MSBDS_ONLY)) + return; + +- if (sched_smt_active()) ++ if (sched_smt_active()) { + static_branch_enable(&mds_idle_clear); +- else ++ } else if (mmio_mitigation == MMIO_MITIGATION_OFF || ++ (ia32_cap & ARCH_CAP_FBSDP_NO)) { + static_branch_disable(&mds_idle_clear); ++ } + } + + #define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" + #define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n" ++#define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n" + + void cpu_bugs_smt_update(void) + { +@@ -1172,6 +1303,16 @@ void cpu_bugs_smt_update(void) + break; + } + ++ switch (mmio_mitigation) { ++ case MMIO_MITIGATION_VERW: ++ case MMIO_MITIGATION_UCODE_NEEDED: ++ if (sched_smt_active()) ++ pr_warn_once(MMIO_MSG_SMT); ++ break; ++ case MMIO_MITIGATION_OFF: ++ break; ++ } ++ + mutex_unlock(&spec_ctrl_mutex); + } + +@@ -1774,6 +1915,20 @@ static ssize_t tsx_async_abort_show_state(char *buf) + sched_smt_active() ? "vulnerable" : "disabled"); + } + ++static ssize_t mmio_stale_data_show_state(char *buf) ++{ ++ if (mmio_mitigation == MMIO_MITIGATION_OFF) ++ return sysfs_emit(buf, "%s\n", mmio_strings[mmio_mitigation]); ++ ++ if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { ++ return sysfs_emit(buf, "%s; SMT Host state unknown\n", ++ mmio_strings[mmio_mitigation]); ++ } ++ ++ return sysfs_emit(buf, "%s; SMT %s\n", mmio_strings[mmio_mitigation], ++ sched_smt_active() ? "vulnerable" : "disabled"); ++} ++ + static char *stibp_state(void) + { + if (spectre_v2_in_eibrs_mode(spectre_v2_enabled)) +@@ -1874,6 +2029,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr + case X86_BUG_SRBDS: + return srbds_show_state(buf); + ++ case X86_BUG_MMIO_STALE_DATA: ++ return mmio_stale_data_show_state(buf); ++ + default: + break; + } +@@ -1925,4 +2083,9 @@ ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char * + { + return cpu_show_common(dev, attr, buf, X86_BUG_SRBDS); + } ++ ++ssize_t cpu_show_mmio_stale_data(struct device *dev, struct device_attribute *attr, char *buf) ++{ ++ return cpu_show_common(dev, attr, buf, X86_BUG_MMIO_STALE_DATA); ++} + #endif +diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c +index e342ae4db3c4d..af5d0c188f7b8 100644 +--- a/arch/x86/kernel/cpu/common.c ++++ b/arch/x86/kernel/cpu/common.c +@@ -1237,18 +1237,42 @@ static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = { + X86_FEATURE_ANY, issues) + + #define SRBDS BIT(0) ++/* CPU is affected by X86_BUG_MMIO_STALE_DATA */ ++#define MMIO BIT(1) ++/* CPU is affected by Shared Buffers Data Sampling (SBDS), a variant of X86_BUG_MMIO_STALE_DATA */ ++#define MMIO_SBDS BIT(2) + + static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = { + VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS), + VULNBL_INTEL_STEPPINGS(HASWELL, X86_STEPPING_ANY, SRBDS), + VULNBL_INTEL_STEPPINGS(HASWELL_L, X86_STEPPING_ANY, SRBDS), + VULNBL_INTEL_STEPPINGS(HASWELL_G, X86_STEPPING_ANY, SRBDS), ++ VULNBL_INTEL_STEPPINGS(HASWELL_X, BIT(2) | BIT(4), MMIO), ++ VULNBL_INTEL_STEPPINGS(BROADWELL_D, X86_STEPPINGS(0x3, 0x5), MMIO), + VULNBL_INTEL_STEPPINGS(BROADWELL_G, X86_STEPPING_ANY, SRBDS), ++ VULNBL_INTEL_STEPPINGS(BROADWELL_X, X86_STEPPING_ANY, MMIO), + VULNBL_INTEL_STEPPINGS(BROADWELL, X86_STEPPING_ANY, SRBDS), ++ VULNBL_INTEL_STEPPINGS(SKYLAKE_L, X86_STEPPINGS(0x3, 0x3), SRBDS | MMIO), + VULNBL_INTEL_STEPPINGS(SKYLAKE_L, X86_STEPPING_ANY, SRBDS), ++ VULNBL_INTEL_STEPPINGS(SKYLAKE_X, BIT(3) | BIT(4) | BIT(6) | ++ BIT(7) | BIT(0xB), MMIO), ++ VULNBL_INTEL_STEPPINGS(SKYLAKE, X86_STEPPINGS(0x3, 0x3), SRBDS | MMIO), + VULNBL_INTEL_STEPPINGS(SKYLAKE, X86_STEPPING_ANY, SRBDS), +- VULNBL_INTEL_STEPPINGS(KABYLAKE_L, X86_STEPPINGS(0x0, 0xC), SRBDS), +- VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPINGS(0x0, 0xD), SRBDS), ++ VULNBL_INTEL_STEPPINGS(KABYLAKE_L, X86_STEPPINGS(0x9, 0xC), SRBDS | MMIO), ++ VULNBL_INTEL_STEPPINGS(KABYLAKE_L, X86_STEPPINGS(0x0, 0x8), SRBDS), ++ VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPINGS(0x9, 0xD), SRBDS | MMIO), ++ VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPINGS(0x0, 0x8), SRBDS), ++ VULNBL_INTEL_STEPPINGS(ICELAKE_L, X86_STEPPINGS(0x5, 0x5), MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(ICELAKE_D, X86_STEPPINGS(0x1, 0x1), MMIO), ++ VULNBL_INTEL_STEPPINGS(ICELAKE_X, X86_STEPPINGS(0x4, 0x6), MMIO), ++ VULNBL_INTEL_STEPPINGS(COMETLAKE, BIT(2) | BIT(3) | BIT(5), MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x0, 0x0), MMIO), ++ VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPINGS(0x1, 0x1), MMIO), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPINGS(0x1, 0x1), MMIO | MMIO_SBDS), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO), ++ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPINGS(0x0, 0x0), MMIO | MMIO_SBDS), + {} + }; + +@@ -1269,6 +1293,13 @@ u64 x86_read_arch_cap_msr(void) + return ia32_cap; + } + ++static bool arch_cap_mmio_immune(u64 ia32_cap) ++{ ++ return (ia32_cap & ARCH_CAP_FBSDP_NO && ++ ia32_cap & ARCH_CAP_PSDP_NO && ++ ia32_cap & ARCH_CAP_SBDR_SSDP_NO); ++} ++ + static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) + { + u64 ia32_cap = x86_read_arch_cap_msr(); +@@ -1322,12 +1353,27 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c) + /* + * SRBDS affects CPUs which support RDRAND or RDSEED and are listed + * in the vulnerability blacklist. ++ * ++ * Some of the implications and mitigation of Shared Buffers Data ++ * Sampling (SBDS) are similar to SRBDS. Give SBDS same treatment as ++ * SRBDS. + */ + if ((cpu_has(c, X86_FEATURE_RDRAND) || + cpu_has(c, X86_FEATURE_RDSEED)) && +- cpu_matches(cpu_vuln_blacklist, SRBDS)) ++ cpu_matches(cpu_vuln_blacklist, SRBDS | MMIO_SBDS)) + setup_force_cpu_bug(X86_BUG_SRBDS); + ++ /* ++ * Processor MMIO Stale Data bug enumeration ++ * ++ * Affected CPU list is generally enough to enumerate the vulnerability, ++ * but for virtualization case check for ARCH_CAP MSR bits also, VMM may ++ * not want the guest to enumerate the bug. ++ */ ++ if (cpu_matches(cpu_vuln_blacklist, MMIO) && ++ !arch_cap_mmio_immune(ia32_cap)) ++ setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA); ++ + if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN)) + return; + +diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c +index 982df9c000d31..9646ae886b4b5 100644 +--- a/arch/x86/kvm/vmx/vmx.c ++++ b/arch/x86/kvm/vmx/vmx.c +@@ -229,6 +229,9 @@ static const struct { + #define L1D_CACHE_ORDER 4 + static void *vmx_l1d_flush_pages; + ++/* Control for disabling CPU Fill buffer clear */ ++static bool __read_mostly vmx_fb_clear_ctrl_available; ++ + static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) + { + struct page *page; +@@ -360,6 +363,60 @@ static int vmentry_l1d_flush_get(char *s, const struct kernel_param *kp) + return sprintf(s, "%s\n", vmentry_l1d_param[l1tf_vmx_mitigation].option); + } + ++static void vmx_setup_fb_clear_ctrl(void) ++{ ++ u64 msr; ++ ++ if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES) && ++ !boot_cpu_has_bug(X86_BUG_MDS) && ++ !boot_cpu_has_bug(X86_BUG_TAA)) { ++ rdmsrl(MSR_IA32_ARCH_CAPABILITIES, msr); ++ if (msr & ARCH_CAP_FB_CLEAR_CTRL) ++ vmx_fb_clear_ctrl_available = true; ++ } ++} ++ ++static __always_inline void vmx_disable_fb_clear(struct vcpu_vmx *vmx) ++{ ++ u64 msr; ++ ++ if (!vmx->disable_fb_clear) ++ return; ++ ++ rdmsrl(MSR_IA32_MCU_OPT_CTRL, msr); ++ msr |= FB_CLEAR_DIS; ++ wrmsrl(MSR_IA32_MCU_OPT_CTRL, msr); ++ /* Cache the MSR value to avoid reading it later */ ++ vmx->msr_ia32_mcu_opt_ctrl = msr; ++} ++ ++static __always_inline void vmx_enable_fb_clear(struct vcpu_vmx *vmx) ++{ ++ if (!vmx->disable_fb_clear) ++ return; ++ ++ vmx->msr_ia32_mcu_opt_ctrl &= ~FB_CLEAR_DIS; ++ wrmsrl(MSR_IA32_MCU_OPT_CTRL, vmx->msr_ia32_mcu_opt_ctrl); ++} ++ ++static void vmx_update_fb_clear_dis(struct kvm_vcpu *vcpu, struct vcpu_vmx *vmx) ++{ ++ vmx->disable_fb_clear = vmx_fb_clear_ctrl_available; ++ ++ /* ++ * If guest will not execute VERW, there is no need to set FB_CLEAR_DIS ++ * at VMEntry. Skip the MSR read/write when a guest has no use case to ++ * execute VERW. ++ */ ++ if ((vcpu->arch.arch_capabilities & ARCH_CAP_FB_CLEAR) || ++ ((vcpu->arch.arch_capabilities & ARCH_CAP_MDS_NO) && ++ (vcpu->arch.arch_capabilities & ARCH_CAP_TAA_NO) && ++ (vcpu->arch.arch_capabilities & ARCH_CAP_PSDP_NO) && ++ (vcpu->arch.arch_capabilities & ARCH_CAP_FBSDP_NO) && ++ (vcpu->arch.arch_capabilities & ARCH_CAP_SBDR_SSDP_NO))) ++ vmx->disable_fb_clear = false; ++} ++ + static const struct kernel_param_ops vmentry_l1d_flush_ops = { + .set = vmentry_l1d_flush_set, + .get = vmentry_l1d_flush_get, +@@ -2252,6 +2309,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) + ret = kvm_set_msr_common(vcpu, msr_info); + } + ++ /* FB_CLEAR may have changed, also update the FB_CLEAR_DIS behavior */ ++ if (msr_index == MSR_IA32_ARCH_CAPABILITIES) ++ vmx_update_fb_clear_dis(vcpu, vmx); ++ + return ret; + } + +@@ -4553,6 +4614,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) + kvm_make_request(KVM_REQ_APIC_PAGE_RELOAD, vcpu); + + vpid_sync_context(vmx->vpid); ++ ++ vmx_update_fb_clear_dis(vcpu, vmx); + } + + static void vmx_enable_irq_window(struct kvm_vcpu *vcpu) +@@ -6773,6 +6836,11 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, + vmx_l1d_flush(vcpu); + else if (static_branch_unlikely(&mds_user_clear)) + mds_clear_cpu_buffers(); ++ else if (static_branch_unlikely(&mmio_stale_data_clear) && ++ kvm_arch_has_assigned_device(vcpu->kvm)) ++ mds_clear_cpu_buffers(); ++ ++ vmx_disable_fb_clear(vmx); + + if (vcpu->arch.cr2 != native_read_cr2()) + native_write_cr2(vcpu->arch.cr2); +@@ -6782,6 +6850,8 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, + + vcpu->arch.cr2 = native_read_cr2(); + ++ vmx_enable_fb_clear(vmx); ++ + guest_state_exit_irqoff(); + } + +@@ -8182,6 +8252,8 @@ static int __init vmx_init(void) + return r; + } + ++ vmx_setup_fb_clear_ctrl(); ++ + for_each_possible_cpu(cpu) { + INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu)); + +diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h +index b98c7e96697a9..8d2342ede0c59 100644 +--- a/arch/x86/kvm/vmx/vmx.h ++++ b/arch/x86/kvm/vmx/vmx.h +@@ -348,6 +348,8 @@ struct vcpu_vmx { + u64 msr_ia32_feature_control_valid_bits; + /* SGX Launch Control public key hash */ + u64 msr_ia32_sgxlepubkeyhash[4]; ++ u64 msr_ia32_mcu_opt_ctrl; ++ bool disable_fb_clear; + + struct pt_desc pt_desc; + struct lbr_desc lbr_desc; +diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c +index 39c571224ac28..558d1f2ab5b49 100644 +--- a/arch/x86/kvm/x86.c ++++ b/arch/x86/kvm/x86.c +@@ -1587,6 +1587,9 @@ static u64 kvm_get_arch_capabilities(void) + */ + } + ++ /* Guests don't need to know "Fill buffer clear control" exists */ ++ data &= ~ARCH_CAP_FB_CLEAR_CTRL; ++ + return data; + } + +diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c +index 2ef23fce0860c..a97776ea9d990 100644 +--- a/drivers/base/cpu.c ++++ b/drivers/base/cpu.c +@@ -564,6 +564,12 @@ ssize_t __weak cpu_show_srbds(struct device *dev, + return sysfs_emit(buf, "Not affected\n"); + } + ++ssize_t __weak cpu_show_mmio_stale_data(struct device *dev, ++ struct device_attribute *attr, char *buf) ++{ ++ return sysfs_emit(buf, "Not affected\n"); ++} ++ + static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL); + static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL); + static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL); +@@ -573,6 +579,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL); + static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL); + static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL); + static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL); ++static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL); + + static struct attribute *cpu_root_vulnerabilities_attrs[] = { + &dev_attr_meltdown.attr, +@@ -584,6 +591,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = { + &dev_attr_tsx_async_abort.attr, + &dev_attr_itlb_multihit.attr, + &dev_attr_srbds.attr, ++ &dev_attr_mmio_stale_data.attr, + NULL + }; + +diff --git a/include/linux/cpu.h b/include/linux/cpu.h +index 54dc2f9a2d56e..2c74773547444 100644 +--- a/include/linux/cpu.h ++++ b/include/linux/cpu.h +@@ -65,6 +65,9 @@ extern ssize_t cpu_show_tsx_async_abort(struct device *dev, + extern ssize_t cpu_show_itlb_multihit(struct device *dev, + struct device_attribute *attr, char *buf); + extern ssize_t cpu_show_srbds(struct device *dev, struct device_attribute *attr, char *buf); ++extern ssize_t cpu_show_mmio_stale_data(struct device *dev, ++ struct device_attribute *attr, ++ char *buf); + + extern __printf(4, 5) + struct device *cpu_device_create(struct device *parent, void *drvdata, +diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h +index 73e643ae94b6f..e17de69faa543 100644 +--- a/tools/arch/x86/include/asm/cpufeatures.h ++++ b/tools/arch/x86/include/asm/cpufeatures.h +@@ -443,5 +443,6 @@ + #define X86_BUG_TAA X86_BUG(22) /* CPU is affected by TSX Async Abort(TAA) */ + #define X86_BUG_ITLB_MULTIHIT X86_BUG(23) /* CPU may incur MCE during certain page attribute changes */ + #define X86_BUG_SRBDS X86_BUG(24) /* CPU may leak RNG bits if not mitigated */ ++#define X86_BUG_MMIO_STALE_DATA X86_BUG(25) /* CPU is affected by Processor MMIO Stale Data vulnerabilities */ + + #endif /* _ASM_X86_CPUFEATURES_H */ +diff --git a/tools/arch/x86/include/asm/msr-index.h b/tools/arch/x86/include/asm/msr-index.h +index ee15311b6be1d..4425d6773183b 100644 +--- a/tools/arch/x86/include/asm/msr-index.h ++++ b/tools/arch/x86/include/asm/msr-index.h +@@ -114,6 +114,30 @@ + * Not susceptible to + * TSX Async Abort (TAA) vulnerabilities. + */ ++#define ARCH_CAP_SBDR_SSDP_NO BIT(13) /* ++ * Not susceptible to SBDR and SSDP ++ * variants of Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_FBSDP_NO BIT(14) /* ++ * Not susceptible to FBSDP variant of ++ * Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_PSDP_NO BIT(15) /* ++ * Not susceptible to PSDP variant of ++ * Processor MMIO stale data ++ * vulnerabilities. ++ */ ++#define ARCH_CAP_FB_CLEAR BIT(17) /* ++ * VERW clears CPU fill buffer ++ * even on MDS_NO CPUs. ++ */ ++#define ARCH_CAP_FB_CLEAR_CTRL BIT(18) /* ++ * MSR_IA32_MCU_OPT_CTRL[FB_CLEAR_DIS] ++ * bit available to control VERW ++ * behavior. ++ */ + + #define MSR_IA32_FLUSH_CMD 0x0000010b + #define L1D_FLUSH BIT(0) /* +@@ -131,6 +155,7 @@ + #define MSR_IA32_MCU_OPT_CTRL 0x00000123 + #define RNGDS_MITG_DIS BIT(0) /* SRBDS support */ + #define RTM_ALLOW BIT(1) /* TSX development mode */ ++#define FB_CLEAR_DIS BIT(3) /* CPU Fill buffer clear disable */ + + #define MSR_IA32_SYSENTER_CS 0x00000174 + #define MSR_IA32_SYSENTER_ESP 0x00000175 |