This is a note to let you know that I've just added the patch titled
KVM: VMX: Fix IBRS handling after vmexit
to the 5.18-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:
kvm-vmx-fix-ibrs-handling-after-vmexit.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue Jul 12 05:03:58 PM CEST 2022
From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Date: Tue, 14 Jun 2022 23:16:14 +0200
Subject: KVM: VMX: Fix IBRS handling after vmexit
From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
commit bea7e31a5caccb6fe8ed989c065072354f0ecb52 upstream.
For legacy IBRS to work, the IBRS bit needs to be always re-written
after vmexit, even if it's already on.
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6845,8 +6845,13 @@ void noinstr vmx_spec_ctrl_restore_host(
/*
* If the guest/host SPEC_CTRL values differ, restore the host value.
+ *
+ * For legacy IBRS, the IBRS bit always needs to be written after
+ * transitioning from a less privileged predictor mode, regardless of
+ * whether the guest/host values differ.
*/
- if (vmx->spec_ctrl != hostval)
+ if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) ||
+ vmx->spec_ctrl != hostval)
native_wrmsrl(MSR_IA32_SPEC_CTRL, hostval);
barrier_nospec();
Patches currently in stable-queue which might be from jpoimboe@xxxxxxxxxx are
queue-5.18/x86-sev-avoid-using-__x86_return_thunk.patch
queue-5.18/kvm-vmx-prevent-rsb-underflow-before-vmenter.patch
queue-5.18/x86-ftrace-use-alternative-ret-encoding.patch
queue-5.18/objtool-re-add-unwind_hint_-save_restore.patch
queue-5.18/x86-bugs-add-retbleed-ibpb.patch
queue-5.18/x86-retpoline-cleanup-some-ifdefery.patch
queue-5.18/kvm-vmx-flatten-__vmx_vcpu_run.patch
queue-5.18/x86-cpu-amd-add-spectral-chicken.patch
queue-5.18/kvm-vmx-fix-ibrs-handling-after-vmexit.patch
queue-5.18/kvm-vmx-prevent-guest-rsb-poisoning-attacks-with-eibrs.patch
queue-5.18/x86-vsyscall_emu-64-don-t-use-ret-in-vsyscall-emulation.patch
queue-5.18/objtool-skip-non-text-sections-when-adding-return-thunk-sites.patch
queue-5.18/x86-bugs-do-ibpb-fallback-check-only-once.patch
queue-5.18/x86-add-magic-amd-return-thunk.patch
queue-5.18/x86-bugs-keep-a-per-cpu-ia32_spec_ctrl-value.patch
queue-5.18/x86-objtool-create-.return_sites.patch
queue-5.18/x86-kvm-fix-setcc-emulation-for-return-thunks.patch
queue-5.18/x86-retpoline-swizzle-retpoline-thunk.patch
queue-5.18/x86-speculation-fix-firmware-entry-spec_ctrl-handling.patch
queue-5.18/x86-speculation-add-spectre_v2-ibrs-option-to-support-kernel-ibrs.patch
queue-5.18/x86-xen-add-untrain_ret.patch
queue-5.18/x86-undo-return-thunk-damage.patch
queue-5.18/x86-speculation-remove-x86_spec_ctrl_mask.patch
queue-5.18/x86-entry-avoid-very-early-ret.patch
queue-5.18/x86-speculation-fill-rsb-on-vmexit-for-ibrs.patch
queue-5.18/objtool-add-entry-unret-validation.patch
queue-5.18/kvm-vmx-convert-launched-argument-to-flags.patch
queue-5.18/x86-bpf-use-alternative-ret-encoding.patch
queue-5.18/x86-bugs-split-spectre_v2_select_mitigation-and-spectre_v2_user_select_mitigation.patch
queue-5.18/x86-bugs-report-intel-retbleed-vulnerability.patch
queue-5.18/x86-cpufeatures-move-retpoline-flags-to-word-11.patch
queue-5.18/x86-speculation-fix-spec_ctrl-write-on-smt-state-change.patch
queue-5.18/x86-retpoline-use-mfunction-return.patch
queue-5.18/x86-xen-rename-sys-entry-points.patch
queue-5.18/x86-bugs-optimize-spec_ctrl-msr-writes.patch
queue-5.18/x86-bugs-report-amd-retbleed-vulnerability.patch
queue-5.18/x86-static_call-use-alternative-ret-encoding.patch
queue-5.18/x86-speculation-fix-rsb-filling-with-config_retpoline-n.patch
queue-5.18/x86-use-return-thunk-in-asm-code.patch
queue-5.18/intel_idle-disable-ibrs-during-long-idle.patch
queue-5.18/x86-speculation-use-cached-host-spec_ctrl-value-for-guest-entry-exit.patch
queue-5.18/x86-bugs-add-amd-retbleed-boot-parameter.patch
queue-5.18/x86-entry-add-kernel-ibrs-implementation.patch
queue-5.18/objtool-treat-.text.__x86.-as-noinstr.patch
queue-5.18/objtool-update-retpoline-validation.patch
