Revert "x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature"

CVE-2017-5753 (revert embargoed)
CVE-2017-5715 (revert embargoed)

This reverts commit 23225db7b02c7f8b94e5d5050987430089e6f7cc.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1738d820c56f99d20c776e6ccc1019552cd0b909..4dcf1b7f84fc9c88fc2bb2bbd57308fdbaee6536 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2566,16 +2566,6 @@
                        noexec=on: enable non-executable mappings (default)
                        noexec=off: disable non-executable mappings
 
-       noibrs          [X86]
-                       Don't use indirect branch restricted speculation (IBRS)
-                       feature when running in secure environment,
-                       to avoid performance overhead.
-
-       noibpb          [X86]
-                       Don't use indirect branch prediction barrier (IBPB)
-                       feature when running in secure environment,
-                       to avoid performance overhead.
-
        nosmap          [X86]
                        Disable SMAP (Supervisor Mode Access Prevention)
                        even if it is supported by processor.

diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index d665daab3f849434237569299ccb0c8cc7f5bce3..f15120ada161641cc4d0cd02896eabe06b13e6a3 100644 (file)
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -107,14 +107,14 @@ static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
                        mb();
                }
 
-               if (ibrs_inuse)
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                        native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
                __monitor((void *)&current_thread_info()->flags, 0, 0);
                if (!need_resched())
                        __mwait(eax, ecx);
 
-               if (ibrs_inuse)
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                        native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
        }
        current_clr_polling();

diff --git a/arch/x86/include/asm/spec_ctrl.h b/arch/x86/include/asm/spec_ctrl.h
index 4c69e51261cc581f0f0542555310512e6fdc148b..55ee1f36bda2e080da48b1ffd52c597a42cfdd65 100644 (file)
--- a/arch/x86/include/asm/spec_ctrl.h
+++ b/arch/x86/include/asm/spec_ctrl.h
@@ -8,9 +8,6 @@
 
 #ifdef __ASSEMBLY__
 
-.extern use_ibrs
-.extern use_ibpb
-
 #define __ASM_ENABLE_IBRS                      \
        pushq %rax;                             \
        pushq %rcx;                             \
@@ -107,30 +104,15 @@
        add $(32*8), %rsp;
 
 .macro ENABLE_IBRS
-       testl   $1, use_ibrs
-       jz      10f
-       __ASM_ENABLE_IBRS
-       jmp 20f
-10:
-       lfence
-20:
+ALTERNATIVE "", __stringify(__ASM_ENABLE_IBRS), X86_FEATURE_SPEC_CTRL
 .endm
 
 .macro ENABLE_IBRS_CLOBBER
-       testl   $1, use_ibrs
-       jz      11f
-       __ASM_ENABLE_IBRS_CLOBBER
-       jmp 21f
-11:
-       lfence
-21:
+ALTERNATIVE "", __stringify(__ASM_ENABLE_IBRS_CLOBBER), X86_FEATURE_SPEC_CTRL
 .endm
 
 .macro DISABLE_IBRS
-       testl   $1, use_ibrs
-       jz      9f
-       __ASM_DISABLE_IBRS
-9:
+ALTERNATIVE "", __stringify(__ASM_DISABLE_IBRS), X86_FEATURE_SPEC_CTRL
 .endm
 
 .macro STUFF_RSB

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index c69ea2efbed1a01df32ba12ccafd8d82b5e6e7cb..f1d94c73625adc3231827c116815ca3322d97627 100644 (file)
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -628,17 +628,10 @@ static void init_intel(struct cpuinfo_x86 *c)
 
        init_intel_misc_features(c);
 
-       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
+       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                 printk_once(KERN_INFO "FEATURE SPEC_CTRL Present\n");
-               set_ibrs_supported();
-               set_ibpb_supported();
-               if (ibrs_inuse)
-                       sysctl_ibrs_enabled = 1;
-               if (ibpb_inuse)
-                       sysctl_ibpb_enabled = 1;
-        } else {
+        else
                 printk_once(KERN_INFO "FEATURE SPEC_CTRL Not Present\n");
-       }
 }
 
 #ifdef CONFIG_X86_32

diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 6450aeda72fcf6d8d21ad3874c2de9774dccb047..c4fa4a85d4cb6f4e0cb4b34cd20467879167463d 100644 (file)
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -535,17 +535,6 @@ static ssize_t reload_store(struct device *dev,
        }
        if (!ret)
                perf_check_microcode();
-
-       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL)) {
-               printk_once(KERN_INFO "FEATURE SPEC_CTRL Present\n");
-               set_ibrs_supported();
-               set_ibpb_supported();
-               if (ibrs_inuse)
-                       sysctl_ibrs_enabled = 1;
-               if (ibpb_inuse)
-                       sysctl_ibpb_enabled = 1;
-       }
-
        mutex_unlock(&microcode_mutex);
        put_online_cpus();
 

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 3fdf5358998e3a0b57b3b1996a37317117c73a92..3adb3806a28495fcd5a27fabf52cfae17a8cbaea 100644 (file)
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -447,16 +447,16 @@ static __cpuidle void mwait_idle(void)
                        mb(); /* quirk */
                }
 
-               if (ibrs_inuse)
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                         native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
                __monitor((void *)&current_thread_info()->flags, 0, 0);
                if (!need_resched()) {
                        __sti_mwait(0, 0);
-                       if (ibrs_inuse)
+                       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                                native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
                } else {
-                       if (ibrs_inuse)
+                       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                                native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
                        local_irq_enable();
                }

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9317aa4a74464fbede48fc4c7339a68de71c323d..a652bff7add4349092ba0e63bb9f1fa0979cb6a9 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1693,14 +1693,14 @@ void native_play_dead(void)
        play_dead_common();
        tboot_shutdown(TB_SHUTDOWN_WFS);
 
-       if (ibrs_inuse)
+       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
        mwait_play_dead();      /* Only returns on failure */
        if (cpuidle_play_dead())
                hlt_play_dead();
 
-       if (ibrs_inuse)
+       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
 }
 

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 9de0cc22eb110cef5c9afaeeb862be4e4e236470..0315e04da49b751ea0e0681970a1a09a02e3b52d 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2265,7 +2265,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
        if (per_cpu(current_vmcs, cpu) != vmx->loaded_vmcs->vmcs) {
                per_cpu(current_vmcs, cpu) = vmx->loaded_vmcs->vmcs;
                vmcs_load(vmx->loaded_vmcs->vmcs);
-               if (ibpb_inuse)
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                        native_wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB);
        }
 
@@ -9040,7 +9040,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 
        atomic_switch_perf_msrs(vmx);
 
-       if (ibrs_inuse)
+       if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
                add_atomic_switch_msr(vmx, MSR_IA32_SPEC_CTRL,
                        vcpu->arch.spec_ctrl, FEATURE_ENABLE_IBRS);
 

diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c
index 72a17464255081b8e45149a8b93499fd0d3b5046..b088463973e4b2fc4d6589dbf0913e4a2fac41fc 100644 (file)
--- a/arch/x86/lib/delay.c
+++ b/arch/x86/lib/delay.c
@@ -107,7 +107,8 @@ static void delay_mwaitx(unsigned long __loops)
        for (;;) {
                delay = min_t(u64, MWAITX_MAX_LOOPS, loops);
 
-               if (ibrs_inuse && (delay > IBRS_DISABLE_THRESHOLD))
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) &&
+                       (delay > IBRS_DISABLE_THRESHOLD))
                        native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
 
                /*
@@ -123,7 +124,8 @@ static void delay_mwaitx(unsigned long __loops)
                 */
                __mwaitx(MWAITX_DISABLE_CSTATES, delay, MWAITX_ECX_TIMER_ENABLE);
 
-               if (ibrs_inuse && (delay > IBRS_DISABLE_THRESHOLD))
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) &&
+                       (delay > IBRS_DISABLE_THRESHOLD))
                        native_wrmsrl(MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
 
                end = rdtsc_ordered();

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 6365f769de3d28f34f58bcf805481fd7be6916f2..301e6efbc5141dc903812b60a72887ca5e16a5ca 100644 (file)
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -221,7 +221,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
                bool need_flush;
 
                /* Null tsk means switching to kernel, so that's safe */
-               if (ibpb_inuse && tsk &&
+               if (boot_cpu_has(X86_FEATURE_SPEC_CTRL) && tsk &&
                        ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB))
                        native_wrmsrl(MSR_IA32_PRED_CMD, FEATURE_SET_IBPB);
 

diff --git a/include/linux/smp.h b/include/linux/smp.h
index e2935c0a1bb4448d1e1dcb1c53b83fa2841cc1a4..68123c1fe54918c051292eb5ba3427df09f31c2f 100644 (file)
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -50,93 +50,6 @@ void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info),
 
 int smp_call_function_single_async(int cpu, struct call_single_data *csd);
 
-#ifdef CONFIG_X86
-/* indicate usage of IBRS to control execution speculation */
-extern int use_ibrs;
-extern u32 sysctl_ibrs_enabled;
-extern struct mutex spec_ctrl_mutex;
-#define ibrs_supported         (use_ibrs & 0x2)
-#define ibrs_disabled          (use_ibrs & 0x4)
-static inline void set_ibrs_inuse(void)
-{
-       if (ibrs_supported)
-               use_ibrs |= 0x1;
-}
-static inline void clear_ibrs_inuse(void)
-{
-       use_ibrs &= ~0x1;
-}
-static inline int check_ibrs_inuse(void)
-{
-       if (use_ibrs & 0x1)
-               return 1;
-       else
-               /* rmb to prevent wrong speculation for security */
-               rmb();
-       return 0;
-}
-static inline void set_ibrs_supported(void)
-{
-       use_ibrs |= 0x2;
-       if (!ibrs_disabled)
-               set_ibrs_inuse();
-}
-static inline void set_ibrs_disabled(void)
-{
-       use_ibrs |= 0x4;
-       if (check_ibrs_inuse())
-               clear_ibrs_inuse();
-}
-static inline void clear_ibrs_disabled(void)
-{
-       use_ibrs &= ~0x4;
-       set_ibrs_inuse();
-}
-#define ibrs_inuse             (check_ibrs_inuse())
-
-/* indicate usage of IBPB to control execution speculation */
-extern int use_ibpb;
-extern u32 sysctl_ibpb_enabled;
-#define ibpb_supported         (use_ibpb & 0x2)
-#define ibpb_disabled          (use_ibpb & 0x4)
-static inline void set_ibpb_inuse(void)
-{
-       if (ibpb_supported)
-               use_ibpb |= 0x1;
-}
-static inline void clear_ibpb_inuse(void)
-{
-       use_ibpb &= ~0x1;
-}
-static inline int check_ibpb_inuse(void)
-{
-       if (use_ibpb & 0x1)
-               return 1;
-       else
-               /* rmb to prevent wrong speculation for security */
-               rmb();
-       return 0;
-}
-static inline void set_ibpb_supported(void)
-{
-       use_ibpb |= 0x2;
-       if (!ibpb_disabled)
-               set_ibpb_inuse();
-}
-static inline void set_ibpb_disabled(void)
-{
-       use_ibpb |= 0x4;
-       if (check_ibpb_inuse())
-               clear_ibpb_inuse();
-}
-static inline void clear_ibpb_disabled(void)
-{
-       use_ibpb &= ~0x4;
-       set_ibpb_inuse();
-}
-#define ibpb_inuse             (check_ibpb_inuse())
-#endif
-
 #ifdef CONFIG_SMP
 
 #include <linux/preempt.h>

diff --git a/kernel/smp.c b/kernel/smp.c
index 3bece045f4a40c8375e867b818393fa97b53da2f..3061483cb3ad3eac437046eda0634f8a152e07f2 100644 (file)
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -498,26 +498,6 @@ EXPORT_SYMBOL(smp_call_function);
 unsigned int setup_max_cpus = NR_CPUS;
 EXPORT_SYMBOL(setup_max_cpus);
 
-#ifdef CONFIG_X86
-/*
- * use IBRS
- * bit 0 = indicate if ibrs is currently in use
- * bit 1 = indicate if system supports ibrs
- * bit 2 = indicate if admin disables ibrs
-*/
-
-int use_ibrs;
-EXPORT_SYMBOL(use_ibrs);
-
-/*
- * use IBRS
- * bit 0 = indicate if ibpb is currently in use
- * bit 1 = indicate if system supports ibpb
- * bit 2 = indicate if admin disables ibpb
-*/
-int use_ibpb;
-EXPORT_SYMBOL(use_ibpb);
-#endif
 
 /*
  * Setup routine for controlling SMP activation
@@ -542,27 +522,6 @@ static int __init nosmp(char *str)
 
 early_param("nosmp", nosmp);
 
-#ifdef CONFIG_X86
-static int __init noibrs(char *str)
-{
-       set_ibrs_disabled();
-
-       return 0;
-}
-
-early_param("noibrs", noibrs);
-
-static int __init noibpb(char *str)
-{
-       set_ibpb_disabled();
-
-       return 0;
-}
-
-early_param("noibpb", noibpb);
-#endif
-
-
 /* this is hard limit */
 static int __init nrcpus(char *str)
 {

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 69c37bd6251a625fd4475352506eb91f0ef38261..7ab08d5728e65dbf0997d5f0b01e2a5a845f565d 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -72,7 +72,6 @@
 #include <asm/processor.h>
 
 #ifdef CONFIG_X86
-#include <asm/msr.h>
 #include <asm/nmi.h>
 #include <asm/stacktrace.h>
 #include <asm/io.h>
@@ -223,15 +222,6 @@ static int proc_dostring_coredump(struct ctl_table *table, int write,
                void __user *buffer, size_t *lenp, loff_t *ppos);
 #endif
 
-#ifdef CONFIG_X86
-int proc_dointvec_ibrs_ctrl(struct ctl_table *table, int write,
-                 void __user *buffer, size_t *lenp, loff_t *ppos);
-int proc_dointvec_ibpb_ctrl(struct ctl_table *table, int write,
-                 void __user *buffer, size_t *lenp, loff_t *ppos);
-int proc_dointvec_ibrs_dump(struct ctl_table *table, int write,
-                 void __user *buffer, size_t *lenp, loff_t *ppos);
-#endif
-
 #ifdef CONFIG_MAGIC_SYSRQ
 /* Note: sysrq code uses it's own private copy */
 static int __sysrq_enabled = CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE;
@@ -268,12 +258,6 @@ extern struct ctl_table epoll_table[];
 int sysctl_legacy_va_layout;
 #endif
 
-u32 sysctl_ibrs_dump = 0;
-u32 sysctl_ibrs_enabled = 0;
-EXPORT_SYMBOL(sysctl_ibrs_enabled);
-u32 sysctl_ibpb_enabled = 0;
-EXPORT_SYMBOL(sysctl_ibpb_enabled);
-
 /* The default sysctl tables: */
 
 static struct ctl_table sysctl_base_table[] = {
@@ -1257,35 +1241,6 @@ static struct ctl_table kern_table[] = {
                .extra1         = &zero,
                .extra2         = &one,
        },
-#endif
-#ifdef CONFIG_X86
-       {
-               .procname       = "ibrs_enabled",
-               .data           = &sysctl_ibrs_enabled,
-               .maxlen         = sizeof(unsigned int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_ibrs_ctrl,
-               .extra1         = &zero,
-               .extra2         = &two,
-       },
-       {
-               .procname       = "ibpb_enabled",
-               .data           = &sysctl_ibpb_enabled,
-               .maxlen         = sizeof(unsigned int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_ibpb_ctrl,
-               .extra1         = &zero,
-               .extra2         = &one,
-       },
-       {
-               .procname       = "ibrs_dump",
-               .data           = &sysctl_ibrs_dump,
-               .maxlen         = sizeof(unsigned int),
-               .mode           = 0644,
-               .proc_handler   = proc_dointvec_ibrs_dump,
-               .extra1         = &zero,
-               .extra2         = &one,
-       },
 #endif
        { }
 };
@@ -2630,86 +2585,6 @@ int proc_dointvec_minmax(struct ctl_table *table, int write,
                                do_proc_dointvec_minmax_conv, &param);
 }
 
-#ifdef CONFIG_X86
-int proc_dointvec_ibrs_dump(struct ctl_table *table, int write,
-       void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-       int ret;
-       unsigned int cpu;
-
-       ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-       printk("sysctl_ibrs_enabled = %u, sysctl_ibpb_enabled = %u\n", sysctl_ibrs_enabled, sysctl_ibpb_enabled);
-       printk("use_ibrs = %d, use_ibpb = %d\n", use_ibrs, use_ibpb);
-       for_each_online_cpu(cpu) {
-              u64 val;
-
-              if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
-                      rdmsrl_on_cpu(cpu, MSR_IA32_SPEC_CTRL, &val);
-              else
-                      val = 0;
-              printk("read cpu %d ibrs val %lu\n", cpu, (unsigned long) val);
-       }
-       return ret;
-}
-
-int proc_dointvec_ibrs_ctrl(struct ctl_table *table, int write,
-       void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-       int ret;
-       unsigned int cpu;
-
-       ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-       pr_debug("sysctl_ibrs_enabled = %u, sysctl_ibpb_enabled = %u\n", sysctl_ibrs_enabled, sysctl_ibpb_enabled);
-       pr_debug("before:use_ibrs = %d, use_ibpb = %d\n", use_ibrs, use_ibpb);
-       if (sysctl_ibrs_enabled == 0) {
-               /* always set IBRS off */
-               set_ibrs_disabled();
-               if (ibrs_supported) {
-                       for_each_online_cpu(cpu)
-                               wrmsrl_on_cpu(cpu, MSR_IA32_SPEC_CTRL, 0x0);
-               }
-       } else if (sysctl_ibrs_enabled == 2) {
-               /* always set IBRS on, even in user space */
-               clear_ibrs_disabled();
-               if (ibrs_supported) {
-                       for_each_online_cpu(cpu)
-                               wrmsrl_on_cpu(cpu, MSR_IA32_SPEC_CTRL, FEATURE_ENABLE_IBRS);
-               } else {
-                       sysctl_ibrs_enabled = 0;
-               }
-       } else if (sysctl_ibrs_enabled == 1) {
-               /* use IBRS in kernel */
-               clear_ibrs_disabled();
-               if (!ibrs_inuse)
-                       /* platform don't support ibrs */
-                       sysctl_ibrs_enabled = 0;
-       }
-       pr_debug("after:use_ibrs = %d, use_ibpb = %d\n", use_ibrs, use_ibpb);
-       return ret;
-}
-
-int proc_dointvec_ibpb_ctrl(struct ctl_table *table, int write,
-       void __user *buffer, size_t *lenp, loff_t *ppos)
-{
-       int ret;
-
-       ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-       pr_debug("sysctl_ibrs_enabled = %u, sysctl_ibpb_enabled = %u\n", sysctl_ibrs_enabled, sysctl_ibpb_enabled);
-       pr_debug("before:use_ibrs = %d, use_ibpb = %d\n", use_ibrs, use_ibpb);
-       if (sysctl_ibpb_enabled == 0)
-               set_ibpb_disabled();
-       else if (sysctl_ibpb_enabled == 1) {
-               clear_ibpb_disabled();
-               if (!ibpb_inuse)
-                       /* platform don't support ibpb */
-                       sysctl_ibpb_enabled = 0;
-       }
-       pr_debug("after:use_ibrs = %d, use_ibpb = %d\n", use_ibrs, use_ibpb);
-       return ret;
-}
-#endif
-
-
 struct do_proc_douintvec_minmax_conv_param {
        unsigned int *min;
        unsigned int *max;