[PATCH 4.19 00/16] 4.19.248-rc1 review

[PATCH 4.19 00/16] 4.19.248-rc1 review

[Greg Kroah-Hartman]

This is the start of the stable review cycle for the 4.19.248 release.
There are 16 patches in this series, all will be posted as a response
to this one.  If anyone has any issues with these being applied, please
let me know.

Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
Anything received after that time might be too late.

The whole patch series can be found in one patch at:
	https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.248-rc1.gz
or in the git tree and branch at:
	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
and the diffstat can be found below.

thanks,

greg k-h

-------------
Pseudo-Shortlog of commits:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Linux 4.19.248-rc1

Josh Poimboeuf <jpoimboe@kernel.org>
    x86/speculation/mmio: Print SMT warning

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    KVM: x86/speculation: Disable Fill buffer clear within guests

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/mmio: Reuse SRBDS mitigation for SBDS

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/srbds: Update SRBDS mitigation selection

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/mmio: Enable CPU Fill buffer clearing on idle

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/bugs: Group MDS, TAA & Processor MMIO Stale Data mitigations

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation: Add a common function for MD_CLEAR mitigation update

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug

Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
    Documentation: Add documentation for Processor MMIO Stale Data

Gayatri Kammela <gayatri.kammela@intel.com>
    x86/cpu: Add another Alder Lake CPU to the Intel family

Tony Luck <tony.luck@intel.com>
    x86/cpu: Add Lakefield, Alder Lake and Rocket Lake models to the to Intel CPU family

Zhang Rui <rui.zhang@intel.com>
    x86/cpu: Add Jasper Lake to Intel family

Guenter Roeck <linux@roeck-us.net>
    cpu/speculation: Add prototype for cpu_show_srbds()

Gayatri Kammela <gayatri.kammela@intel.com>
    x86/cpu: Add Elkhart Lake to Intel family


-------------

Diffstat:

 Documentation/ABI/testing/sysfs-devices-system-cpu |   1 +
 Documentation/admin-guide/hw-vuln/index.rst        |   1 +
 .../hw-vuln/processor_mmio_stale_data.rst          | 246 +++++++++++++++++++++
 Documentation/admin-guide/kernel-parameters.txt    |  36 +++
 Makefile                                           |   4 +-
 arch/x86/include/asm/cpufeatures.h                 |   1 +
 arch/x86/include/asm/intel-family.h                |  11 +
 arch/x86/include/asm/msr-index.h                   |  25 +++
 arch/x86/include/asm/nospec-branch.h               |   2 +
 arch/x86/kernel/cpu/bugs.c                         | 235 +++++++++++++++++---
 arch/x86/kernel/cpu/common.c                       |  52 ++++-
 arch/x86/kvm/vmx.c                                 |  77 ++++++-
 arch/x86/kvm/x86.c                                 |   4 +
 drivers/base/cpu.c                                 |   8 +
 include/linux/cpu.h                                |   4 +
 15 files changed, 665 insertions(+), 42 deletions(-)

[PATCH 4.19 01/16] x86/cpu: Add Elkhart Lake to Intel family

[Greg Kroah-Hartman]

From: Gayatri Kammela <gayatri.kammela@intel.com>

commit 0f65605a8d744b3a205d0a2cd8f20707e31fc023 upstream.

Add the model number/CPUID of atom based Elkhart Lake to the Intel
family.

Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rahul Tanwar <rahul.tanwar@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190905193020.14707-3-tony.luck@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/intel-family.h |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -83,7 +83,9 @@
 #define INTEL_FAM6_ATOM_GOLDMONT	0x5C /* Apollo Lake */
 #define INTEL_FAM6_ATOM_GOLDMONT_X	0x5F /* Denverton */
 #define INTEL_FAM6_ATOM_GOLDMONT_PLUS	0x7A /* Gemini Lake */
+
 #define INTEL_FAM6_ATOM_TREMONT_X	0x86 /* Jacobsville */
+#define INTEL_FAM6_ATOM_TREMONT		0x96 /* Elkhart Lake */
 
 /* Xeon Phi */
 

[PATCH 4.19 02/16] cpu/speculation: Add prototype for cpu_show_srbds()

[Greg Kroah-Hartman]

From: Guenter Roeck <linux@roeck-us.net>

commit 2accfa69050c2a0d6fc6106f609208b3e9622b26 upstream.

0-day is not happy that there is no prototype for cpu_show_srbds():

drivers/base/cpu.c:565:16: error: no previous prototype for 'cpu_show_srbds'

Fixes: 7e5b3c267d25 ("x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200617141410.93338-1-linux@roeck-us.net
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/cpu.h |    1 +
 1 file changed, 1 insertion(+)

--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -64,6 +64,7 @@ extern ssize_t cpu_show_tsx_async_abort(
 					char *buf);
 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 __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,

[PATCH 4.19 03/16] x86/cpu: Add Jasper Lake to Intel family

[Greg Kroah-Hartman]

From: Zhang Rui <rui.zhang@intel.com>

commit b2d32af0bff402b4c1fce28311759dd1f6af058a upstream.

Japser Lake is an Atom family processor.
It uses Tremont cores and is targeted at mobile platforms.

Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/intel-family.h |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -86,6 +86,7 @@
 
 #define INTEL_FAM6_ATOM_TREMONT_X	0x86 /* Jacobsville */
 #define INTEL_FAM6_ATOM_TREMONT		0x96 /* Elkhart Lake */
+#define INTEL_FAM6_ATOM_TREMONT_L	0x9C /* Jasper Lake */
 
 /* Xeon Phi */
 

[PATCH 4.19 04/16] x86/cpu: Add Lakefield, Alder Lake and Rocket Lake models to the to Intel CPU family

[Greg Kroah-Hartman]

From: Tony Luck <tony.luck@intel.com>

commit e00b62f0b06d0ae2b844049f216807617aff0cdb upstream.

Add three new Intel CPU models.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20200721043749.31567-1-tony.luck@intel.com
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/intel-family.h |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -64,6 +64,13 @@
 #define INTEL_FAM6_COMETLAKE		0xA5
 #define INTEL_FAM6_COMETLAKE_L		0xA6
 
+#define INTEL_FAM6_ROCKETLAKE		0xA7
+
+/* Hybrid Core/Atom Processors */
+
+#define	INTEL_FAM6_LAKEFIELD		0x8A
+#define INTEL_FAM6_ALDERLAKE		0x97
+
 /* "Small Core" Processors (Atom) */
 
 #define INTEL_FAM6_ATOM_BONNELL		0x1C /* Diamondville, Pineview */

[PATCH 4.19 05/16] x86/cpu: Add another Alder Lake CPU to the Intel family

[Greg Kroah-Hartman]

From: Gayatri Kammela <gayatri.kammela@intel.com>

commit 6e1239c13953f3c2a76e70031f74ddca9ae57cd3 upstream.

Add Alder Lake mobile CPU model number to Intel family.

Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20210121215004.11618-1-tony.luck@intel.com
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/intel-family.h |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/x86/include/asm/intel-family.h
+++ b/arch/x86/include/asm/intel-family.h
@@ -70,6 +70,7 @@
 
 #define	INTEL_FAM6_LAKEFIELD		0x8A
 #define INTEL_FAM6_ALDERLAKE		0x97
+#define INTEL_FAM6_ALDERLAKE_L		0x9A
 
 /* "Small Core" Processors (Atom) */
 

[PATCH 4.19 06/16] Documentation: Add documentation for Processor MMIO Stale Data

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 4419470191386456e0b8ed4eb06a70b0021798a6 upstream

Add the admin guide for Processor MMIO stale data vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/admin-guide/hw-vuln/index.rst                     |    1 
 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst |  246 ++++++++++
 2 files changed, 247 insertions(+)
 create mode 100644 Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst

--- a/Documentation/admin-guide/hw-vuln/index.rst
+++ b/Documentation/admin-guide/hw-vuln/index.rst
@@ -15,3 +15,4 @@ are configurable at compile, boot or run
    tsx_async_abort
    multihit.rst
    special-register-buffer-data-sampling.rst
+   processor_mmio_stale_data.rst
--- /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

[PATCH 4.19 07/16] x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 51802186158c74a0304f51ab963e7c2b3a2b046f upstream

Processor MMIO Stale Data is a class of vulnerabilities that may
expose data after an MMIO operation. For more details please refer to
Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst

Add the Processor MMIO Stale Data bug enumeration. A microcode update
adds new bits to the MSR IA32_ARCH_CAPABILITIES, define them.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[cascardo: adapted family names to the ones in v4.19]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/cpufeatures.h |    1 
 arch/x86/include/asm/msr-index.h   |   19 ++++++++++++++++
 arch/x86/kernel/cpu/common.c       |   43 +++++++++++++++++++++++++++++++++++--
 3 files changed, 61 insertions(+), 2 deletions(-)

--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -394,5 +394,6 @@
 #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 */
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -96,6 +96,25 @@
 						 * 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 MSR_IA32_FLUSH_CMD		0x0000010b
 #define L1D_FLUSH			BIT(0)	/*
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1019,18 +1019,39 @@ static const __initconst struct x86_cpu_
 					    X86_FEATURE_ANY, issues)
 
 #define SRBDS		BIT(0)
+/* CPU is affected by X86_BUG_MMIO_STALE_DATA */
+#define MMIO		BIT(1)
 
 static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
 	VULNBL_INTEL_STEPPINGS(IVYBRIDGE,	X86_STEPPING_ANY,		SRBDS),
 	VULNBL_INTEL_STEPPINGS(HASWELL_CORE,	X86_STEPPING_ANY,		SRBDS),
 	VULNBL_INTEL_STEPPINGS(HASWELL_ULT,	X86_STEPPING_ANY,		SRBDS),
 	VULNBL_INTEL_STEPPINGS(HASWELL_GT3E,	X86_STEPPING_ANY,		SRBDS),
+	VULNBL_INTEL_STEPPINGS(HASWELL_X,	BIT(2) | BIT(4),		MMIO),
+	VULNBL_INTEL_STEPPINGS(BROADWELL_XEON_D,X86_STEPPINGS(0x3, 0x5),	MMIO),
 	VULNBL_INTEL_STEPPINGS(BROADWELL_GT3E,	X86_STEPPING_ANY,		SRBDS),
+	VULNBL_INTEL_STEPPINGS(BROADWELL_X,	X86_STEPPING_ANY,		MMIO),
 	VULNBL_INTEL_STEPPINGS(BROADWELL_CORE,	X86_STEPPING_ANY,		SRBDS),
+	VULNBL_INTEL_STEPPINGS(SKYLAKE_MOBILE,	X86_STEPPINGS(0x3, 0x3),	SRBDS | MMIO),
 	VULNBL_INTEL_STEPPINGS(SKYLAKE_MOBILE,	X86_STEPPING_ANY,		SRBDS),
+	VULNBL_INTEL_STEPPINGS(SKYLAKE_X,	BIT(3) | BIT(4) | BIT(6) |
+						BIT(7) | BIT(0xB),              MMIO),
+	VULNBL_INTEL_STEPPINGS(SKYLAKE_DESKTOP,	X86_STEPPINGS(0x3, 0x3),	SRBDS | MMIO),
 	VULNBL_INTEL_STEPPINGS(SKYLAKE_DESKTOP,	X86_STEPPING_ANY,		SRBDS),
-	VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE,	X86_STEPPINGS(0x0, 0xC),	SRBDS),
-	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x0, 0xD),	SRBDS),
+	VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE,	X86_STEPPINGS(0x9, 0xC),	SRBDS | MMIO),
+	VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE,	X86_STEPPINGS(0x0, 0x8),	SRBDS),
+	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x9, 0xD),	SRBDS | MMIO),
+	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x0, 0x8),	SRBDS),
+	VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE,	X86_STEPPINGS(0x5, 0x5),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ICELAKE_XEON_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),
+	VULNBL_INTEL_STEPPINGS(COMETLAKE_L,	X86_STEPPINGS(0x0, 0x1),	MMIO),
+	VULNBL_INTEL_STEPPINGS(LAKEFIELD,	X86_STEPPINGS(0x1, 0x1),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ROCKETLAKE,	X86_STEPPINGS(0x1, 0x1),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT,	X86_STEPPINGS(0x1, 0x1),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_X,	X86_STEPPING_ANY,		MMIO),
+	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L,	X86_STEPPINGS(0x0, 0x0),	MMIO),
 	{}
 };
 
@@ -1051,6 +1072,13 @@ 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();
@@ -1108,6 +1136,17 @@ static void __init cpu_set_bug_bits(stru
 	    cpu_matches(cpu_vuln_blacklist, SRBDS))
 		    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;
 

[PATCH 4.19 08/16] x86/speculation: Add a common function for MD_CLEAR mitigation update

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit f52ea6c26953fed339aa4eae717ee5c2133c7ff2 upstream

Processor MMIO Stale Data mitigation uses similar mitigation as MDS and
TAA. In preparation for adding its mitigation, add a common function to
update all mitigations that depend on MD_CLEAR.

  [ bp: Add a newline in md_clear_update_mitigation() to separate
    statements better. ]

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |   59 +++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 26 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -40,7 +40,7 @@ static void __init spectre_v2_select_mit
 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 taa_select_mitigation(void);
 static void __init srbds_select_mitigation(void);
 
@@ -113,10 +113,10 @@ void __init check_bugs(void)
 	srbds_select_mitigation();
 
 	/*
-	 * As MDS and TAA mitigations are inter-related, print MDS
-	 * mitigation until after TAA mitigation selection is done.
+	 * As MDS and TAA mitigations are inter-related, update and print their
+	 * mitigation after TAA mitigation selection is done.
 	 */
-	mds_print_mitigation();
+	md_clear_update_mitigation();
 
 	arch_smt_update();
 
@@ -257,14 +257,6 @@ static void __init mds_select_mitigation
 	}
 }
 
-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))
@@ -312,7 +304,7 @@ static void __init taa_select_mitigation
 	/* 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()) {
@@ -326,7 +318,7 @@ static void __init taa_select_mitigation
 	 */
 	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;
@@ -358,18 +350,6 @@ static void __init taa_select_mitigation
 
 	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)
@@ -394,6 +374,33 @@ static int __init tsx_async_abort_parse_
 early_param("tsx_async_abort", tsx_async_abort_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 mitigation, if
+	 * necessary.
+	 */
+	if (mds_mitigation == MDS_MITIGATION_OFF &&
+	    boot_cpu_has_bug(X86_BUG_MDS)) {
+		mds_mitigation = MDS_MITIGATION_FULL;
+		mds_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]);
+}
+
+#undef pr_fmt
 #define pr_fmt(fmt)	"SRBDS: " fmt
 
 enum srbds_mitigations {

[PATCH 4.19 09/16] x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 8cb861e9e3c9a55099ad3d08e1a3b653d29c33ca upstream

Processor MMIO Stale Data is a class of vulnerabilities that may
expose data after an MMIO operation. For details please refer to
Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst.

These vulnerabilities are broadly categorized as:

Device Register Partial Write (DRPW):
  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 some processors, this may expose stale
  data from the fill buffers of the core that created the write
  transaction.

Shared Buffers Data Sampling (SBDS):
  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.

Shared Buffers Data Read (SBDR):
  It is similar to Shared Buffer Data Sampling (SBDS) except that the
  data is directly read into the architectural software-visible state.

An attacker can use these vulnerabilities to extract data from CPU fill
buffers using MDS and TAA methods. Mitigate it by clearing the CPU fill
buffers using the VERW instruction before returning to a user or a
guest.

On CPUs not affected by MDS and TAA, user application cannot sample data
from CPU fill buffers using MDS or TAA. A guest with MMIO access can
still use DRPW or SBDR to extract data architecturally. Mitigate it with
VERW instruction to clear fill buffers before VMENTER for MMIO capable
guests.

Add a kernel parameter mmio_stale_data={off|full|full,nosmt} to control
the mitigation.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[cascardo: arch/x86/kvm/vmx.c has been moved]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/admin-guide/kernel-parameters.txt |   36 +++++++
 arch/x86/include/asm/nospec-branch.h            |    2 
 arch/x86/kernel/cpu/bugs.c                      |  111 +++++++++++++++++++++++-
 arch/x86/kvm/vmx.c                              |    3 
 4 files changed, 148 insertions(+), 4 deletions(-)

--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2574,6 +2574,7 @@
 					       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
@@ -2595,6 +2596,7 @@
 				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
@@ -2604,6 +2606,40 @@
 			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.
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -323,6 +323,8 @@ DECLARE_STATIC_KEY_FALSE(switch_mm_alway
 DECLARE_STATIC_KEY_FALSE(mds_user_clear);
 DECLARE_STATIC_KEY_FALSE(mds_idle_clear);
 
+DECLARE_STATIC_KEY_FALSE(mmio_stale_data_clear);
+
 #include <asm/segment.h>
 
 /**
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -42,6 +42,7 @@ static void __init l1tf_select_mitigatio
 static void __init mds_select_mitigation(void);
 static void __init md_clear_update_mitigation(void);
 static void __init taa_select_mitigation(void);
+static void __init mmio_select_mitigation(void);
 static void __init srbds_select_mitigation(void);
 
 /* The base value of the SPEC_CTRL MSR that always has to be preserved. */
@@ -76,6 +77,10 @@ EXPORT_SYMBOL_GPL(mds_user_clear);
 DEFINE_STATIC_KEY_FALSE(mds_idle_clear);
 EXPORT_SYMBOL_GPL(mds_idle_clear);
 
+/* 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();
@@ -110,11 +115,13 @@ void __init check_bugs(void)
 	l1tf_select_mitigation();
 	mds_select_mitigation();
 	taa_select_mitigation();
+	mmio_select_mitigation();
 	srbds_select_mitigation();
 
 	/*
-	 * As MDS and TAA mitigations are inter-related, update and print their
-	 * mitigation after TAA mitigation selection is done.
+	 * 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();
 
@@ -374,6 +381,90 @@ static int __init tsx_async_abort_parse_
 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);
+
+	/*
+	 * 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)
@@ -385,19 +476,31 @@ static void __init md_clear_update_mitig
 		goto out;
 
 	/*
-	 * mds_user_clear is now enabled. Update MDS mitigation, if
-	 * necessary.
+	 * 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]);
 }
 
 #undef pr_fmt
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -10773,6 +10773,9 @@ static void __noclone vmx_vcpu_run(struc
 		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();
 
 	asm volatile (
 		/* Store host registers */

[PATCH 4.19 10/16] x86/bugs: Group MDS, TAA & Processor MMIO Stale Data mitigations

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit e5925fb867290ee924fcf2fe3ca887b792714366 upstream

MDS, TAA and Processor MMIO Stale Data mitigations rely on clearing CPU
buffers. Moreover, status of these mitigations affects each other.
During boot, it is important to maintain the order in which these
mitigations are selected. This is especially true for
md_clear_update_mitigation() that needs to be called after MDS, TAA and
Processor MMIO Stale Data mitigation selection is done.

Introduce md_clear_select_mitigation(), and select all these mitigations
from there. This reflects relationships between these mitigations and
ensures proper ordering.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |   26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -41,6 +41,7 @@ static void __init ssb_select_mitigation
 static void __init l1tf_select_mitigation(void);
 static void __init mds_select_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);
@@ -113,18 +114,9 @@ void __init check_bugs(void)
 	spectre_v2_select_mitigation();
 	ssb_select_mitigation();
 	l1tf_select_mitigation();
-	mds_select_mitigation();
-	taa_select_mitigation();
-	mmio_select_mitigation();
+	md_clear_select_mitigation();
 	srbds_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();
-
 	arch_smt_update();
 
 #ifdef CONFIG_X86_32
@@ -503,6 +495,20 @@ out:
 		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
 

[PATCH 4.19 11/16] x86/speculation/mmio: Enable CPU Fill buffer clearing on idle

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 99a83db5a605137424e1efe29dc0573d6a5b6316 upstream

When the CPU is affected by Processor MMIO Stale Data vulnerabilities,
Fill Buffer Stale Data Propagator (FBSDP) can propagate stale data out
of Fill buffer to uncore buffer when CPU goes idle. Stale data can then
be exploited with other variants using MMIO operations.

Mitigate it by clearing the Fill buffer before entering idle state.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -417,6 +417,14 @@ static void __init mmio_select_mitigatio
 		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
@@ -1182,6 +1190,8 @@ static void update_indir_branch_cond(voi
 /* 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.
@@ -1193,10 +1203,12 @@ 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"

[PATCH 4.19 12/16] x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 8d50cdf8b8341770bc6367bce40c0c1bb0e1d5b3 upstream

Add the sysfs reporting file for Processor MMIO Stale Data
vulnerability. It exposes the vulnerability and mitigation state similar
to the existing files for the other hardware vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 Documentation/ABI/testing/sysfs-devices-system-cpu |    1 
 arch/x86/kernel/cpu/bugs.c                         |   22 +++++++++++++++++++++
 drivers/base/cpu.c                                 |    8 +++++++
 include/linux/cpu.h                                |    3 ++
 4 files changed, 34 insertions(+)

--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -481,6 +481,7 @@ What:		/sys/devices/system/cpu/vulnerabi
 		/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
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1808,6 +1808,20 @@ static ssize_t tsx_async_abort_show_stat
 		       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))
@@ -1908,6 +1922,9 @@ static ssize_t cpu_show_common(struct de
 	case X86_BUG_SRBDS:
 		return srbds_show_state(buf);
 
+	case X86_BUG_MMIO_STALE_DATA:
+		return mmio_stale_data_show_state(buf);
+
 	default:
 		break;
 	}
@@ -1959,4 +1976,9 @@ ssize_t cpu_show_srbds(struct device *de
 {
 	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
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -571,6 +571,12 @@ ssize_t __weak cpu_show_srbds(struct dev
 	return sprintf(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);
@@ -580,6 +586,7 @@ static DEVICE_ATTR(mds, 0444, cpu_show_m
 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,
@@ -591,6 +598,7 @@ static struct attribute *cpu_root_vulner
 	&dev_attr_tsx_async_abort.attr,
 	&dev_attr_itlb_multihit.attr,
 	&dev_attr_srbds.attr,
+	&dev_attr_mmio_stale_data.attr,
 	NULL
 };
 
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -65,6 +65,9 @@ extern ssize_t cpu_show_tsx_async_abort(
 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,

[PATCH 4.19 13/16] x86/speculation/srbds: Update SRBDS mitigation selection

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 22cac9c677c95f3ac5c9244f8ca0afdc7c8afb19 upstream

Currently, Linux disables SRBDS mitigation on CPUs not affected by
MDS and have the TSX feature disabled. On such CPUs, secrets cannot
be extracted from CPU fill buffers using MDS or TAA. Without SRBDS
mitigation, Processor MMIO Stale Data vulnerabilities can be used to
extract RDRAND, RDSEED, and EGETKEY data.

Do not disable SRBDS mitigation by default when CPU is also affected by
Processor MMIO Stale Data vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -578,11 +578,13 @@ static void __init srbds_select_mitigati
 		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;

[PATCH 4.19 14/16] x86/speculation/mmio: Reuse SRBDS mitigation for SBDS

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit a992b8a4682f119ae035a01b40d4d0665c4a2875 upstream

The Shared Buffers Data Sampling (SBDS) variant of Processor MMIO Stale
Data vulnerabilities may expose RDRAND, RDSEED and SGX EGETKEY data.
Mitigation for this is added by a microcode update.

As some of the implications of SBDS are similar to SRBDS, SRBDS mitigation
infrastructure can be leveraged by SBDS. Set X86_BUG_SRBDS and use SRBDS
mitigation.

Mitigation is enabled by default; use srbds=off to opt-out. Mitigation
status can be checked from below file:

  /sys/devices/system/cpu/vulnerabilities/srbds

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[cascardo: adjust for processor model names]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/common.c |   21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1021,6 +1021,8 @@ static const __initconst struct x86_cpu_
 #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),
@@ -1042,16 +1044,17 @@ static const struct x86_cpu_id cpu_vuln_
 	VULNBL_INTEL_STEPPINGS(KABYLAKE_MOBILE,	X86_STEPPINGS(0x0, 0x8),	SRBDS),
 	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x9, 0xD),	SRBDS | MMIO),
 	VULNBL_INTEL_STEPPINGS(KABYLAKE_DESKTOP,X86_STEPPINGS(0x0, 0x8),	SRBDS),
-	VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE,	X86_STEPPINGS(0x5, 0x5),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ICELAKE_MOBILE,	X86_STEPPINGS(0x5, 0x5),	MMIO | MMIO_SBDS),
 	VULNBL_INTEL_STEPPINGS(ICELAKE_XEON_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),
-	VULNBL_INTEL_STEPPINGS(COMETLAKE_L,	X86_STEPPINGS(0x0, 0x1),	MMIO),
-	VULNBL_INTEL_STEPPINGS(LAKEFIELD,	X86_STEPPINGS(0x1, 0x1),	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),
+	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT,	X86_STEPPINGS(0x1, 0x1),	MMIO | MMIO_SBDS),
 	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_X,	X86_STEPPING_ANY,		MMIO),
-	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L,	X86_STEPPINGS(0x0, 0x0),	MMIO),
+	VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L,	X86_STEPPINGS(0x0, 0x0),	MMIO | MMIO_SBDS),
 	{}
 };
 
@@ -1130,10 +1133,14 @@ static void __init cpu_set_bug_bits(stru
 	/*
 	 * 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);
 
 	/*

[PATCH 4.19 15/16] KVM: x86/speculation: Disable Fill buffer clear within guests

[Greg Kroah-Hartman]

From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>

commit 027bbb884be006b05d9c577d6401686053aa789e upstream

The enumeration of MD_CLEAR in CPUID(EAX=7,ECX=0).EDX{bit 10} is not an
accurate indicator on all CPUs of whether the VERW instruction will
overwrite fill buffers. FB_CLEAR enumeration in
IA32_ARCH_CAPABILITIES{bit 17} covers the case of CPUs that are not
vulnerable to MDS/TAA, indicating that microcode does overwrite fill
buffers.

Guests running in VMM environments may not be aware of all the
capabilities/vulnerabilities of the host CPU. Specifically, a guest may
apply MDS/TAA mitigations when a virtual CPU is enumerated as vulnerable
to MDS/TAA even when the physical CPU is not. On CPUs that enumerate
FB_CLEAR_CTRL the VMM may set FB_CLEAR_DIS to skip overwriting of fill
buffers by the VERW instruction. This is done by setting FB_CLEAR_DIS
during VMENTER and resetting on VMEXIT. For guests that enumerate
FB_CLEAR (explicitly asking for fill buffer clear capability) the VMM
will not use FB_CLEAR_DIS.

Irrespective of guest state, host overwrites CPU buffers before VMENTER
to protect itself from an MMIO capable guest, as part of mitigation for
MMIO Stale Data vulnerabilities.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[cascardo: arch/x86/kvm/vmx.c has been split and context adjustment at
 vmx_vcpu_run]
[cascardo: moved functions so they are after struct vcpu_vmx definition]
[cascardo: fb_clear is disabled/enabled around __vmx_vcpu_run]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/include/asm/msr-index.h |    6 +++
 arch/x86/kvm/vmx.c               |   74 ++++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c               |    4 ++
 3 files changed, 83 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -115,6 +115,11 @@
 						 * 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)	/*
@@ -132,6 +137,7 @@
 /* SRBDS support */
 #define MSR_IA32_MCU_OPT_CTRL		0x00000123
 #define RNGDS_MITG_DIS			BIT(0)
+#define FB_CLEAR_DIS			BIT(3)	/* CPU Fill buffer clear disable */
 
 #define MSR_IA32_SYSENTER_CS		0x00000174
 #define MSR_IA32_SYSENTER_ESP		0x00000175
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -212,6 +212,9 @@ 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;
@@ -1045,6 +1048,8 @@ struct vcpu_vmx {
 	u64 msr_ia32_feature_control;
 	u64 msr_ia32_feature_control_valid_bits;
 	u64 ept_pointer;
+	u64 msr_ia32_mcu_opt_ctrl;
+	bool disable_fb_clear;
 };
 
 enum segment_cache_field {
@@ -2107,6 +2112,60 @@ static inline void __invept(unsigned lon
 	BUG_ON(error);
 }
 
+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 struct shared_msr_entry *find_msr_entry(struct vcpu_vmx *vmx, u32 msr)
 {
 	int i;
@@ -4314,9 +4373,13 @@ static int vmx_set_msr(struct kvm_vcpu *
 			}
 			break;
 		}
-		ret = kvm_set_msr_common(vcpu, 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;
 }
 
@@ -6761,6 +6824,8 @@ static void vmx_vcpu_reset(struct kvm_vc
 	vpid_sync_context(vmx->vpid);
 	if (init_event)
 		vmx_clear_hlt(vcpu);
+
+	vmx_update_fb_clear_dis(vcpu, vmx);
 }
 
 /*
@@ -10777,6 +10842,8 @@ static void __noclone vmx_vcpu_run(struc
 		 kvm_arch_has_assigned_device(vcpu->kvm))
 		mds_clear_cpu_buffers();
 
+	vmx_disable_fb_clear(vmx);
+
 	asm volatile (
 		/* Store host registers */
 		"push %%" _ASM_DX "; push %%" _ASM_BP ";"
@@ -10921,6 +10988,8 @@ static void __noclone vmx_vcpu_run(struc
 #endif
 	      );
 
+	vmx_enable_fb_clear(vmx);
+
 	/*
 	 * We do not use IBRS in the kernel. If this vCPU has used the
 	 * SPEC_CTRL MSR it may have left it on; save the value and
@@ -14626,8 +14695,11 @@ static int __init vmx_init(void)
 		}
 	}
 
+	vmx_setup_fb_clear_ctrl();
+
 	for_each_possible_cpu(cpu) {
 		INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
+
 		INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
 		spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
 	}
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1220,6 +1220,10 @@ u64 kvm_get_arch_capabilities(void)
 
 	/* KVM does not emulate MSR_IA32_TSX_CTRL.  */
 	data &= ~ARCH_CAP_TSX_CTRL_MSR;
+
+	/* Guests don't need to know "Fill buffer clear control" exists */
+	data &= ~ARCH_CAP_FB_CLEAR_CTRL;
+
 	return data;
 }
 

[PATCH 4.19 16/16] x86/speculation/mmio: Print SMT warning

[Greg Kroah-Hartman]

From: Josh Poimboeuf <jpoimboe@kernel.org>

commit 1dc6ff02c8bf77d71b9b5d11cbc9df77cfb28626 upstream

Similar to MDS and TAA, print a warning if SMT is enabled for the MMIO
Stale Data vulnerability.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1215,6 +1215,7 @@ static void update_mds_branch_idle(void)
 
 #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 arch_smt_update(void)
 {
@@ -1259,6 +1260,16 @@ void arch_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);
 }
 

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Shuah Khan]

On 6/14/22 12:40 PM, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.
> 
> The whole patch series can be found in one patch at:
> 	https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.248-rc1.gz
> or in the git tree and branch at:
> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
> and the diffstat can be found below.
> 
> thanks,
> 
> greg k-h
> 

Compiled and booted on my test system. No dmesg regressions.

Tested-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Sudip Mukherjee]

Hi Greg,

On Tue, Jun 14, 2022 at 08:40:01PM +0200, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.

Build test (gcc version 11.3.1 20220612):
mips: 63 configs -> no  failure
arm: 115 configs -> no failure
arm64: 2 configs -> no failure
x86_64: 4 configs -> no failure
alpha allmodconfig -> no failure
s390 allmodconfig -> no failure
xtensa allmodconfig -> no failure

Boot test:
x86_64: Booted on my test laptop. No regression.
x86_64: Booted on qemu. No regression. [1]

[1]. https://openqa.qa.codethink.co.uk/tests/1338


Tested-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>

--
Regards
Sudip

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Naresh Kamboju]

On Wed, 15 Jun 2022 at 00:12, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
>
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.
>
> The whole patch series can be found in one patch at:
>         https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.248-rc1.gz
> or in the git tree and branch at:
>         git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
> and the diffstat can be found below.
>
> thanks,
>
> greg k-h

Results from Linaro’s test farm.
No regressions on arm64, arm, x86_64, and i386.

Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>

## Build
* kernel: 4.19.248-rc1
* git: https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc
* git branch: linux-4.19.y
* git commit: 3a3ddc084a29f6b9346b3f7de410b1c5353cbcd0
* git describe: v4.19.247-17-g3a3ddc084a29
* test details:
https://qa-reports.linaro.org/lkft/linux-stable-rc-linux-4.19.y/build/v4.19.247-17-g3a3ddc084a29

## Test Regressions (compared to v4.19.247)
No test regressions found.

## Metric Regressions (compared to v4.19.247)
No metric regressions found.

## Test Fixes (compared to v4.19.247)
No test fixes found.

## Metric Fixes (compared to v4.19.247)
No metric fixes found.

## Test result summary
total: 103967, pass: 92252, fail: 235, skip: 10777, xfail: 703

## Build Summary
* arc: 10 total, 10 passed, 0 failed
* arm: 298 total, 292 passed, 6 failed
* arm64: 56 total, 54 passed, 2 failed
* i386: 27 total, 23 passed, 4 failed
* mips: 27 total, 27 passed, 0 failed
* parisc: 12 total, 12 passed, 0 failed
* powerpc: 55 total, 54 passed, 1 failed
* s390: 12 total, 12 passed, 0 failed
* sh: 24 total, 24 passed, 0 failed
* sparc: 12 total, 12 passed, 0 failed
* x86_64: 53 total, 51 passed, 2 failed

## Test suites summary
* fwts
* igt-gpu-tools
* kunit
* kvm-unit-tests
* libhugetlbfs
* log-parser-boot
* log-parser-test
* ltp-cap_bounds
* ltp-cap_bounds-tests
* ltp-commands
* ltp-commands-tests
* ltp-containers
* ltp-containers-tests
* ltp-controllers-tests
* ltp-cpuhotplug-tests
* ltp-crypto
* ltp-crypto-tests
* ltp-cve-tests
* ltp-dio-tests
* ltp-fcntl-locktests
* ltp-fcntl-locktests-tests
* ltp-filecaps
* ltp-filecaps-tests
* ltp-fs
* ltp-fs-tests
* ltp-fs_bind
* ltp-fs_bind-tests
* ltp-fs_perms_simple
* ltp-fs_perms_simple-tests
* ltp-fsx
* ltp-fsx-tests
* ltp-hugetlb
* ltp-hugetlb-tests
* ltp-io
* ltp-io-tests
* ltp-ipc
* ltp-ipc-tests
* ltp-math-tests
* ltp-mm-tests
* ltp-nptl
* ltp-nptl-tests
* ltp-open-posix-tests
* ltp-pty
* ltp-pty-tests
* ltp-sched
* ltp-sched-tests
* ltp-securebits
* ltp-securebits-tests
* ltp-smoke
* ltp-syscalls-tests
* ltp-tracing-tests
* network-basic-tests
* packetdrill
* rcutorture
* ssuite
* v4l2-compliance
* vdso

--
Linaro LKFT
https://lkft.linaro.org

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Guenter Roeck]

On Tue, Jun 14, 2022 at 08:40:01PM +0200, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.
> 

Build results:
	total: 157 pass: 157 fail: 0
Qemu test results:
	total: 425 pass: 425 fail: 0

Tested-by: Guenter Roeck <linux@roeck-us.net>

Guenter

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Samuel Zou]

On 2022/6/15 2:40, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.
> 
> The whole patch series can be found in one patch at:
> 	https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.248-rc1.gz
> or in the git tree and branch at:
> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
> and the diffstat can be found below.
> 
> thanks,
> 
> greg k-h
> 

Tested on arm64 and x86 for 4.19.248-rc1,

Kernel repo:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
Branch: linux-4.19.y
Version: 4.19.248-rc1
Commit: 3a3ddc084a29f6b9346b3f7de410b1c5353cbcd0
Compiler: gcc version 7.3.0 (GCC)

arm64:
--------------------------------------------------------------------
Testcase Result Summary:
total: 8956
passed: 8956
failed: 0
timeout: 0
--------------------------------------------------------------------

x86:
--------------------------------------------------------------------
Testcase Result Summary:
total: 8956
passed: 8956
failed: 0
timeout: 0
--------------------------------------------------------------------

Tested-by: Hulk Robot <hulkrobot@huawei.com>

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Jon Hunter]

On 14/06/2022 19:40, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Thu, 16 Jun 2022 18:37:02 +0000.
> Anything received after that time might be too late.
> 
> The whole patch series can be found in one patch at:
> 	https://www.kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.19.248-rc1.gz
> or in the git tree and branch at:
> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-4.19.y
> and the diffstat can be found below.
> 
> thanks,
> 
> greg k-h

All tests passing for Tegra ...

Test results for stable-v4.19:
     10 builds:	10 pass, 0 fail
     22 boots:	22 pass, 0 fail
     40 tests:	40 pass, 0 fail

Linux version:	4.19.248-rc1-g3a3ddc084a29
Boards tested:	tegra124-jetson-tk1, tegra186-p2771-0000,
                 tegra194-p2972-0000, tegra20-ventana,
                 tegra210-p2371-2180, tegra30-cardhu-a04

Tested-by: Jon Hunter <jonathanh@nvidia.com>

Jon

-- 
nvpublic

Re: [PATCH 4.19 00/16] 4.19.248-rc1 review

[Pavel Machek]

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Hi!

> This is the start of the stable review cycle for the 4.19.248 release.
> There are 16 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.

CIP testing did not find any problems here:

https://gitlab.com/cip-project/cip-testing/linux-stable-rc-ci/-/tree/linux-4.19.y

Tested-by: Pavel Machek (CIP) <pavel@denx.de>

Best regards,
                                                                Pavel


-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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