This is a note to let you know that I've just added the patch titled x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit 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: x86-speculation-use-cached-host-spec_ctrl-value-for-guest-entry-exit.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 23:16:08 +0200 Subject: x86/speculation: Use cached host SPEC_CTRL value for guest entry/exit From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> commit bbb69e8bee1bd882784947095ffb2bfe0f7c9470 upstream. There's no need to recalculate the host value for every entry/exit. Just use the cached value in spec_ctrl_current(). 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/kernel/cpu/bugs.c | 12 +----------- 1 file changed, 1 insertion(+), 11 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -208,7 +208,7 @@ void __init check_bugs(void) void x86_virt_spec_ctrl(u64 guest_spec_ctrl, u64 guest_virt_spec_ctrl, bool setguest) { - u64 msrval, guestval, hostval = x86_spec_ctrl_base; + u64 msrval, guestval, hostval = spec_ctrl_current(); struct thread_info *ti = current_thread_info(); /* Is MSR_SPEC_CTRL implemented ? */ @@ -221,15 +221,6 @@ x86_virt_spec_ctrl(u64 guest_spec_ctrl, guestval = hostval & ~x86_spec_ctrl_mask; guestval |= guest_spec_ctrl & x86_spec_ctrl_mask; - /* SSBD controlled in MSR_SPEC_CTRL */ - if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || - static_cpu_has(X86_FEATURE_AMD_SSBD)) - hostval |= ssbd_tif_to_spec_ctrl(ti->flags); - - /* Conditional STIBP enabled? */ - if (static_branch_unlikely(&switch_to_cond_stibp)) - hostval |= stibp_tif_to_spec_ctrl(ti->flags); - if (hostval != guestval) { msrval = setguest ? guestval : hostval; wrmsrl(MSR_IA32_SPEC_CTRL, msrval); @@ -1390,7 +1381,6 @@ static void __init spectre_v2_select_mit pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); if (spectre_v2_in_ibrs_mode(mode)) { - /* Force it so VMEXIT will restore correctly */ x86_spec_ctrl_base |= SPEC_CTRL_IBRS; write_spec_ctrl_current(x86_spec_ctrl_base, true); } 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