On Thu, Apr 04, 2019 at 11:44:12AM -0500, Josh Poimboeuf wrote: > Configure x86 runtime CPU speculation bug mitigations in accordance with > the 'cpu_spec_mitigations=' cmdline options. This affects Meltdown, > Spectre v2, Speculative Store Bypass, and L1TF. > > The default behavior is unchanged. > > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > --- > .../admin-guide/kernel-parameters.txt | 15 +++++++++ > arch/x86/include/asm/processor.h | 1 + > arch/x86/kernel/cpu/bugs.c | 32 ++++++++++++++++--- > arch/x86/kvm/vmx/vmx.c | 2 ++ > arch/x86/mm/pti.c | 4 ++- > 5 files changed, 49 insertions(+), 5 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index ac42e510bd6e..29dc03971630 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -2552,6 +2552,11 @@ > > off > Disable all speculative CPU mitigations. > + Equivalent to: nopti [x86] > + nospectre_v2 [x86] > + spectre_v2_user=off [x86] > + spec_store_bypass_disable=off [x86] > + l1tf=off [x86] > > auto (default) > Mitigate all speculative CPU vulnerabilities, > @@ -2560,12 +2565,22 @@ > surprised by SMT getting disabled across kernel > upgrades, or who have other ways of avoiding > SMT-based attacks. > + Equivalent to: pti=auto [x86] > + spectre_v2=auto [x86] > + spectre_v2_user=auto [x86] > + spec_store_bypass_disable=auto [x86] > + l1tf=flush [x86] > > auto,nosmt > Mitigate all speculative CPU vulnerabilities, > disabling SMT if needed. This is for users who > always want to be fully mitigated, even if it > means losing SMT. > + Equivalent to: pti=auto [x86] > + spectre_v2=auto [x86] > + spectre_v2_user=auto [x86] > + spec_store_bypass_disable=auto [x86] > + l1tf=flush,nosmt [x86] > > mminit_loglevel= > [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this Yap, those sets look ok. > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index 2bb3a648fc12..7e95b310f869 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -982,6 +982,7 @@ void microcode_check(void); > > enum l1tf_mitigations { > L1TF_MITIGATION_OFF, > + L1TF_MITIGATION_DEFAULT, > L1TF_MITIGATION_FLUSH_NOWARN, > L1TF_MITIGATION_FLUSH, > L1TF_MITIGATION_FLUSH_NOSMT, > diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c > index 2da82eff0eb4..65b95fb95ba5 100644 > --- a/arch/x86/kernel/cpu/bugs.c > +++ b/arch/x86/kernel/cpu/bugs.c > @@ -308,8 +308,11 @@ spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd) > > ret = cmdline_find_option(boot_command_line, "spectre_v2_user", > arg, sizeof(arg)); > - if (ret < 0) > + if (ret < 0) { > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > + return SPECTRE_V2_USER_CMD_NONE; Instead of sprinkling that test in those three functions, just do it once above in check_bugs(), before those *_select_mitigation() functions get to run and depending on the value, you either run them or use the default settings, for the OFF case, for example. > return SPECTRE_V2_USER_CMD_AUTO; > + } > > for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { > if (match_option(arg, ret, v2_user_options[i].option)) { > @@ -444,8 +447,11 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) > return SPECTRE_V2_CMD_NONE; > > ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg)); > - if (ret < 0) > + if (ret < 0) { > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > + return SPECTRE_V2_CMD_NONE; > return SPECTRE_V2_CMD_AUTO; > + } > > for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) { > if (!match_option(arg, ret, mitigation_options[i].option)) > @@ -677,8 +683,11 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) > } else { > ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable", > arg, sizeof(arg)); > - if (ret < 0) > + if (ret < 0) { > + if (cpu_spec_mitigations == CPU_SPEC_MITIGATIONS_OFF) > + return SPEC_STORE_BYPASS_CMD_NONE; > return SPEC_STORE_BYPASS_CMD_AUTO; > + } > > for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) { > if (!match_option(arg, ret, ssb_mitigation_options[i].option)) > @@ -955,7 +964,7 @@ void x86_spec_ctrl_setup_ap(void) > #define pr_fmt(fmt) "L1TF: " fmt > > /* Default mitigation for L1TF-affected CPUs */ > -enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH; > +enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_DEFAULT; > #if IS_ENABLED(CONFIG_KVM_INTEL) > EXPORT_SYMBOL_GPL(l1tf_mitigation); > #endif > @@ -1010,8 +1019,23 @@ static void __init l1tf_select_mitigation(void) > > override_cache_bits(&boot_cpu_data); > > + if (l1tf_mitigation == L1TF_MITIGATION_DEFAULT) { > + switch (cpu_spec_mitigations) { > + case CPU_SPEC_MITIGATIONS_OFF: > + l1tf_mitigation = L1TF_MITIGATION_OFF; > + break; > + case CPU_SPEC_MITIGATIONS_AUTO: > + l1tf_mitigation = L1TF_MITIGATION_FLUSH; > + break; > + case CPU_SPEC_MITIGATIONS_AUTO_NOSMT: > + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; > + break; > + } > + } > + > switch (l1tf_mitigation) { > case L1TF_MITIGATION_OFF: > + case L1TF_MITIGATION_DEFAULT: > case L1TF_MITIGATION_FLUSH_NOWARN: > case L1TF_MITIGATION_FLUSH: > break; > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index ab432a930ae8..83b5bdc3c777 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -233,6 +233,7 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) > case L1TF_MITIGATION_FLUSH_NOWARN: > case L1TF_MITIGATION_FLUSH: > case L1TF_MITIGATION_FLUSH_NOSMT: > + case L1TF_MITIGATION_DEFAULT: > l1tf = VMENTER_L1D_FLUSH_COND; > break; > case L1TF_MITIGATION_FULL: > @@ -6686,6 +6687,7 @@ static int vmx_vm_init(struct kvm *kvm) > case L1TF_MITIGATION_FLUSH: > case L1TF_MITIGATION_FLUSH_NOSMT: > case L1TF_MITIGATION_FULL: > + case L1TF_MITIGATION_DEFAULT: > /* > * Warn upon starting the first VM in a potentially > * insecure environment. The L1TF bits need to be a separate patch. Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.