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 5.4-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: kvm-vmx-fix-ibrs-handling-after-vmexit.patch and it can be found in the queue-5.4 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 Wed Oct 5 12:28:43 PM CEST 2022 From: Thadeu Lima de Souza Cascardo <cascardo@xxxxxxxxxxxxx> Date: Mon, 3 Oct 2022 10:10:30 -0300 Subject: KVM: VMX: Fix IBRS handling after vmexit To: stable@xxxxxxxxxxxxxxx Cc: x86@xxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, bp@xxxxxxxxx, pbonzini@xxxxxxxxxx, peterz@xxxxxxxxxxxxx, jpoimboe@xxxxxxxxxx Message-ID: <20221003131038.12645-30-cascardo@xxxxxxxxxxxxx> 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 @@ -6571,8 +6571,13 @@ 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 cascardo@xxxxxxxxxxxxx are queue-5.4/x86-speculation-disable-rrsba-behavior.patch queue-5.4/kvm-vmx-flatten-__vmx_vcpu_run.patch queue-5.4/x86-kvm-vmx-make-noinstr-clean.patch queue-5.4/revert-x86-speculation-add-rsb-vm-exit-protections.patch queue-5.4/kvm-vmx-fix-ibrs-handling-after-vmexit.patch queue-5.4/kvm-vmx-prevent-guest-rsb-poisoning-attacks-with-eibrs.patch queue-5.4/kvm-nvmx-use-__vmx_vcpu_run-in-nested_vmx_check_vmentry_hw.patch queue-5.4/x86-bugs-keep-a-per-cpu-ia32_spec_ctrl-value.patch queue-5.4/x86-cpu-amd-enumerate-btc_no.patch queue-5.4/x86-speculation-fix-firmware-entry-spec_ctrl-handling.patch queue-5.4/x86-speculation-add-spectre_v2-ibrs-option-to-support-kernel-ibrs.patch queue-5.4/x86-cpu-add-consistent-cpu-match-macros.patch queue-5.4/x86-speculation-remove-x86_spec_ctrl_mask.patch queue-5.4/x86-bugs-add-cannon-lake-to-retbleed-affected-cpu-list.patch queue-5.4/x86-bugs-warn-when-ibrs-mitigation-is-selected-on-enhanced-ibrs-parts.patch queue-5.4/x86-speculation-fill-rsb-on-vmexit-for-ibrs.patch queue-5.4/x86-cpu-add-a-steppings-field-to-struct-x86_cpu_id.patch queue-5.4/kvm-vmx-convert-launched-argument-to-flags.patch queue-5.4/x86-common-stamp-out-the-stepping-madness.patch queue-5.4/x86-bugs-split-spectre_v2_select_mitigation-and-spectre_v2_user_select_mitigation.patch queue-5.4/x86-bugs-report-intel-retbleed-vulnerability.patch queue-5.4/x86-speculation-change-fill_return_buffer-to-work-with-objtool.patch queue-5.4/x86-cpufeatures-move-retpoline-flags-to-word-11.patch queue-5.4/x86-speculation-fix-spec_ctrl-write-on-smt-state-change.patch queue-5.4/kvm-vmx-use-test-reg-reg-instead-of-cmp-0-reg-in-vmenter.s.patch queue-5.4/x86-bugs-optimize-spec_ctrl-msr-writes.patch queue-5.4/x86-bugs-report-amd-retbleed-vulnerability.patch queue-5.4/x86-speculation-fix-rsb-filling-with-config_retpoline-n.patch queue-5.4/intel_idle-disable-ibrs-during-long-idle.patch queue-5.4/x86-speculation-use-declare_per_cpu-for-x86_spec_ctrl_current.patch queue-5.4/x86-entry-remove-skip_r11rcx.patch queue-5.4/x86-speculation-use-cached-host-spec_ctrl-value-for-guest-entry-exit.patch queue-5.4/x86-devicetable-move-x86-specific-macro-out-of-generic-code.patch queue-5.4/x86-bugs-add-amd-retbleed-boot-parameter.patch queue-5.4/x86-entry-add-kernel-ibrs-implementation.patch queue-5.4/revert-x86-cpu-add-a-steppings-field-to-struct-x86_cpu_id.patch queue-5.4/x86-speculation-add-rsb-vm-exit-protections.patch