Patch "x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-xen-zero-msr_ia32_spec_ctrl-before-suspend.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From foo@baz Mon Jul 23 10:04:05 CEST 2018
From: "Srivatsa S. Bhat" <srivatsa@csail.mit.edu>
Date: Sat, 14 Jul 2018 02:31:49 -0700
Subject: x86/xen: Zero MSR_IA32_SPEC_CTRL before suspend
To: gregkh@linuxfoundation.org, stable@vger.kernel.org
Cc: Juergen Gross <jgross@suse.com>, Thomas Gleixner <tglx@linutronix.de>, Jan Beulich <jbeulich@suse.com>, xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com, "Matt Helsley \(VMware\)" <matt.helsley@gmail.com>, Alexey Makhalov <amakhalov@vmware.com>, Bo Gan <ganb@vmware.com>, matt.helsley@gmail.com, rostedt@goodmis.org, amakhalov@vmware.com, ganb@vmware.com, srivatsa@csail.mit.edu, srivatsab@vmware.com
Message-ID: <153156070962.10043.13374276305669211495.stgit@srivatsa-ubuntu>

From: Juergen Gross <jgross@suse.com>

commit 71c208dd54ab971036d83ff6d9837bae4976e623 upstream.

Older Xen versions (4.5 and before) might have problems migrating pv
guests with MSR_IA32_SPEC_CTRL having a non-zero value. So before
suspending zero that MSR and restore it after being resumed.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Cc: stable@vger.kernel.org
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Link: https://lkml.kernel.org/r/20180226140818.4849-1-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

 arch/x86/xen/suspend.c |   16 ++++++++++++++++
 1 file changed, 16 insertions(+)

--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -1,11 +1,14 @@
 #include <linux/types.h>
 #include <linux/tick.h>
+#include <linux/percpu-defs.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
 #include <xen/grant_table.h>
 #include <xen/events.h>
 
+#include <asm/cpufeatures.h>
+#include <asm/msr-index.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/page.h>
 #include <asm/fixmap.h>
@@ -68,6 +71,8 @@ static void xen_pv_post_suspend(int susp
 	xen_mm_unpin_all();
 }
 
+static DEFINE_PER_CPU(u64, spec_ctrl);
+
 void xen_arch_pre_suspend(void)
 {
 	if (xen_pv_domain())
@@ -84,6 +89,9 @@ void xen_arch_post_suspend(int cancelled
 
 static void xen_vcpu_notify_restore(void *data)
 {
+	if (xen_pv_domain() && boot_cpu_has(X86_FEATURE_SPEC_CTRL))
+		wrmsrl(MSR_IA32_SPEC_CTRL, this_cpu_read(spec_ctrl));
+
 	/* Boot processor notified via generic timekeeping_resume() */
 	if (smp_processor_id() == 0)
 		return;
@@ -93,7 +101,15 @@ static void xen_vcpu_notify_restore(void
 
 static void xen_vcpu_notify_suspend(void *data)
 {
+	u64 tmp;
+
 	tick_suspend_local();
+
+	if (xen_pv_domain() && boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
+		rdmsrl(MSR_IA32_SPEC_CTRL, tmp);
+		this_cpu_write(spec_ctrl, tmp);
+		wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+	}
 }
 
 void xen_arch_resume(void)


Patches currently in stable-queue which might be from srivatsa@csail.mit.edu are

queue-4.4/x86-bugs-rename-_rds-to-_ssbd.patch
queue-4.4/x86-speculation-remove-skylake-c2-from-speculation-control-microcode-blacklist.patch
queue-4.4/documentation-spec_ctrl-do-some-minor-cleanups.patch
queue-4.4/x86-speculation-handle-ht-correctly-on-amd.patch
queue-4.4/x86-cpufeatures-add-x86_feature_rds.patch
queue-4.4/x86-speculation-fix-up-array_index_nospec_mask-asm-constraint.patch
queue-4.4/x86-bugs-remove-x86_spec_ctrl_set.patch
queue-4.4/x86-speculation-add-asm-msr-index.h-dependency.patch
queue-4.4/x86-cpu-intel-add-knights-mill-to-intel-family.patch
queue-4.4/x86-bugs-concentrate-bug-detection-into-a-separate-function.patch
queue-4.4/x86-bugs-fix-the-parameters-alignment-and-missing-void.patch
queue-4.4/x86-bugs-whitelist-allowed-spec_ctrl-msr-values.patch
queue-4.4/prctl-add-force-disable-speculation.patch
queue-4.4/x86-cpufeatures-add-intel-feature-bits-for-speculation-control.patch
queue-4.4/x86-speculation-use-synthetic-bits-for-ibrs-ibpb-stibp.patch
queue-4.4/x86-cpuid-fix-up-virtual-ibrs-ibpb-stibp-feature-bits-on-intel.patch
queue-4.4/x86-nospec-simplify-alternative_msr_write.patch
queue-4.4/x86-bugs-intel-set-proper-cpu-features-and-setup-rds.patch
queue-4.4/x86-speculation-use-indirect-branch-prediction-barrier-in-context-switch.patch
queue-4.4/x86-process-correct-and-optimize-tif_blockstep-switch.patch
queue-4.4/x86-speculation-use-ibrs-if-available-before-calling-into-firmware.patch
queue-4.4/x86-speculation-rework-speculative_store_bypass_update.patch
queue-4.4/x86-asm-entry-32-simplify-pushes-of-zeroed-pt_regs-regs.patch
queue-4.4/x86-bugs-make-cpu_show_common-static.patch
queue-4.4/seccomp-use-pr_spec_force_disable.patch
queue-4.4/x86-cpufeatures-disentangle-ssbd-enumeration.patch
queue-4.4/x86-cpu-amd-fix-erratum-1076-cpb-bit.patch
queue-4.4/x86-speculation-correct-speculation-control-microcode-blacklist-again.patch
queue-4.4/x86-cpu-rename-merrifield2-to-moorefield.patch
queue-4.4/x86-cpu-make-alternative_msr_write-work-for-32-bit-code.patch
queue-4.4/x86-cpufeatures-disentangle-msr_spec_ctrl-enumeration-from-ibrs.patch
queue-4.4/x86-cpufeatures-add-cpuid_7_edx-cpuid-leaf.patch
queue-4.4/x86-bugs-fix-__ssb_select_mitigation-return-type.patch
queue-4.4/x86-cpufeatures-add-feature_zen.patch
queue-4.4/xen-set-cpu-capabilities-from-xen_start_kernel.patch
queue-4.4/x86-bugs-rename-ssbd_no-to-ssb_no.patch
queue-4.4/x86-speculation-add-prctl-for-speculative-store-bypass-mitigation.patch
queue-4.4/x86-msr-add-definitions-for-new-speculation-control-msrs.patch
queue-4.4/seccomp-enable-speculation-flaw-mitigations.patch
queue-4.4/x86-spectre_v2-don-t-check-microcode-versions-when-running-under-hypervisors.patch
queue-4.4/selftest-seccomp-fix-the-seccomp-2-signature.patch
queue-4.4/proc-use-underscores-for-ssbd-in-status.patch
queue-4.4/x86-bugs-amd-add-support-to-disable-rds-on-famh-if-requested.patch
queue-4.4/x86-cpufeature-blacklist-spec_ctrl-pred_cmd-on-early-spectre-v2-microcodes.patch
queue-4.4/x86-bugs-rework-spec_ctrl-base-and-mask-logic.patch
queue-4.4/seccomp-add-filter-flag-to-opt-out-of-ssb-mitigation.patch
queue-4.4/x86-speculation-make-seccomp-the-default-mode-for-speculative-store-bypass.patch
queue-4.4/x86-bugs-kvm-support-the-combination-of-guest-and-host-ibrs.patch
queue-4.4/selftest-seccomp-fix-the-flag-name-seccomp_filter_flag_tsync.patch
queue-4.4/x86-mm-factor-out-ldt-init-from-context-init.patch
queue-4.4/x86-speculation-create-spec-ctrl.h-to-avoid-include-hell.patch
queue-4.4/x86-cpufeatures-clean-up-spectre-v2-related-cpuid-flags.patch
queue-4.4/x86-bugs-expose-sys-..-spec_store_bypass.patch
queue-4.4/nospec-allow-getting-setting-on-non-current-task.patch
queue-4.4/x86-speculation-clean-up-various-spectre-related-details.patch
queue-4.4/x86-bugs-concentrate-bug-reporting-into-a-separate-function.patch
queue-4.4/x86-pti-mark-constant-arrays-as-__initconst.patch
queue-4.4/x86-cpufeatures-add-amd-feature-bits-for-speculation-control.patch
queue-4.4/x86-pti-do-not-enable-pti-on-cpus-which-are-not-vulnerable-to-meltdown.patch
queue-4.4/x86-mm-give-each-mm-tlb-flush-generation-a-unique-id.patch
queue-4.4/seccomp-move-speculation-migitation-control-to-arch-code.patch
queue-4.4/x86-speculation-move-firmware_restrict_branch_speculation_-from-c-to-cpp.patch
queue-4.4/x86-xen-zero-msr_ia32_spec_ctrl-before-suspend.patch
queue-4.4/x86-amd-don-t-set-x86_bug_sysret_ss_attrs-when-running-under-xen.patch
queue-4.4/x86-bugs-kvm-extend-speculation-control-for-virt_spec_ctrl.patch
queue-4.4/prctl-add-speculation-control-prctls.patch
queue-4.4/x86-process-optimize-tif_notsc-switch.patch
queue-4.4/x86-process-allow-runtime-control-of-speculative-store-bypass.patch
queue-4.4/x86-bugs-unify-x86_spec_ctrl_-set_guest-restore_host.patch
queue-4.4/x86-bugs-expose-x86_spec_ctrl_base-directly.patch
queue-4.4/x86-bugs-provide-boot-parameters-for-the-spec_store_bypass_disable-mitigation.patch
queue-4.4/x86-speculation-update-speculation-control-microcode-blacklist.patch
queue-4.4/proc-provide-details-on-speculation-flaw-mitigations.patch
queue-4.4/x86-speculation-add-basic-ibpb-indirect-branch-prediction-barrier-support.patch
queue-4.4/x86-speculation-kvm-implement-support-for-virt_spec_ctrl-ls_cfg.patch
queue-4.4/x86-entry-64-compat-clear-registers-for-compat-syscalls-to-reduce-speculation-attack-surface.patch
queue-4.4/x86-process-optimize-tif-checks-in-__switch_to_xtra.patch
queue-4.4/x86-speculation-add-virtualized-speculative-store-bypass-disable-support.patch
queue-4.4/x86-bugs-read-spec_ctrl-msr-during-boot-and-re-use-reserved-bits.patch

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