Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 pti updates from Thomas Gleixner:
 "No point in speculating what's in this parcel:

   - Drop the swap storage limit when L1TF is disabled so the full space
     is available

   - Add support for the new AMD STIBP always on mitigation mode

   - Fix a bunch of STIPB typos"

* 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Add support for STIBP always-on preferred mode
  x86/speculation/l1tf: Drop the swap storage limit restriction when l1tf=off
  x86/speculation: Change misspelled STIPB to STIBP
This commit is contained in:
Linus Torvalds 2018-12-25 16:26:42 -08:00
commit 13e1ad2be3
7 changed files with 39 additions and 13 deletions

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@ -2099,6 +2099,9 @@
off
Disables hypervisor mitigations and doesn't
emit any warnings.
It also drops the swap size and available
RAM limit restriction on both hypervisor and
bare metal.
Default is 'flush'.

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@ -405,6 +405,9 @@ time with the option "l1tf=". The valid arguments for this option are:
off Disables hypervisor mitigations and doesn't emit any
warnings.
It also drops the swap size and available RAM limit restrictions
on both hypervisor and bare metal.
============ =============================================================
The default is 'flush'. For details about L1D flushing see :ref:`l1d_flush`.
@ -576,7 +579,8 @@ Default mitigations
The kernel default mitigations for vulnerable processors are:
- PTE inversion to protect against malicious user space. This is done
unconditionally and cannot be controlled.
unconditionally and cannot be controlled. The swap storage is limited
to ~16TB.
- L1D conditional flushing on VMENTER when EPT is enabled for
a guest.

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@ -284,6 +284,7 @@
#define X86_FEATURE_AMD_IBPB (13*32+12) /* "" Indirect Branch Prediction Barrier */
#define X86_FEATURE_AMD_IBRS (13*32+14) /* "" Indirect Branch Restricted Speculation */
#define X86_FEATURE_AMD_STIBP (13*32+15) /* "" Single Thread Indirect Branch Predictors */
#define X86_FEATURE_AMD_STIBP_ALWAYS_ON (13*32+17) /* "" Single Thread Indirect Branch Predictors always-on preferred */
#define X86_FEATURE_AMD_SSBD (13*32+24) /* "" Speculative Store Bypass Disable */
#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
#define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */

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@ -232,6 +232,7 @@ enum spectre_v2_mitigation {
enum spectre_v2_user_mitigation {
SPECTRE_V2_USER_NONE,
SPECTRE_V2_USER_STRICT,
SPECTRE_V2_USER_STRICT_PREFERRED,
SPECTRE_V2_USER_PRCTL,
SPECTRE_V2_USER_SECCOMP,
};

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@ -54,7 +54,7 @@ static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
u64 __ro_after_init x86_amd_ls_cfg_base;
u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
/* Control conditional STIPB in switch_to() */
/* Control conditional STIBP in switch_to() */
DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
/* Control conditional IBPB in switch_mm() */
DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
@ -262,10 +262,11 @@ enum spectre_v2_user_cmd {
};
static const char * const spectre_v2_user_strings[] = {
[SPECTRE_V2_USER_NONE] = "User space: Vulnerable",
[SPECTRE_V2_USER_STRICT] = "User space: Mitigation: STIBP protection",
[SPECTRE_V2_USER_PRCTL] = "User space: Mitigation: STIBP via prctl",
[SPECTRE_V2_USER_SECCOMP] = "User space: Mitigation: STIBP via seccomp and prctl",
[SPECTRE_V2_USER_NONE] = "User space: Vulnerable",
[SPECTRE_V2_USER_STRICT] = "User space: Mitigation: STIBP protection",
[SPECTRE_V2_USER_STRICT_PREFERRED] = "User space: Mitigation: STIBP always-on protection",
[SPECTRE_V2_USER_PRCTL] = "User space: Mitigation: STIBP via prctl",
[SPECTRE_V2_USER_SECCOMP] = "User space: Mitigation: STIBP via seccomp and prctl",
};
static const struct {
@ -355,6 +356,15 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
break;
}
/*
* At this point, an STIBP mode other than "off" has been set.
* If STIBP support is not being forced, check if STIBP always-on
* is preferred.
*/
if (mode != SPECTRE_V2_USER_STRICT &&
boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
mode = SPECTRE_V2_USER_STRICT_PREFERRED;
/* Initialize Indirect Branch Prediction Barrier */
if (boot_cpu_has(X86_FEATURE_IBPB)) {
setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
@ -379,12 +389,12 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
"always-on" : "conditional");
}
/* If enhanced IBRS is enabled no STIPB required */
/* If enhanced IBRS is enabled no STIBP required */
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
/*
* If SMT is not possible or STIBP is not available clear the STIPB
* If SMT is not possible or STIBP is not available clear the STIBP
* mode.
*/
if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
@ -610,6 +620,7 @@ void arch_smt_update(void)
case SPECTRE_V2_USER_NONE:
break;
case SPECTRE_V2_USER_STRICT:
case SPECTRE_V2_USER_STRICT_PREFERRED:
update_stibp_strict();
break;
case SPECTRE_V2_USER_PRCTL:
@ -812,7 +823,8 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
* Indirect branch speculation is always disabled in strict
* mode.
*/
if (spectre_v2_user == SPECTRE_V2_USER_STRICT)
if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
return -EPERM;
task_clear_spec_ib_disable(task);
task_update_spec_tif(task);
@ -825,7 +837,8 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
*/
if (spectre_v2_user == SPECTRE_V2_USER_NONE)
return -EPERM;
if (spectre_v2_user == SPECTRE_V2_USER_STRICT)
if (spectre_v2_user == SPECTRE_V2_USER_STRICT ||
spectre_v2_user == SPECTRE_V2_USER_STRICT_PREFERRED)
return 0;
task_set_spec_ib_disable(task);
if (ctrl == PR_SPEC_FORCE_DISABLE)
@ -896,6 +909,7 @@ static int ib_prctl_get(struct task_struct *task)
return PR_SPEC_PRCTL | PR_SPEC_DISABLE;
return PR_SPEC_PRCTL | PR_SPEC_ENABLE;
case SPECTRE_V2_USER_STRICT:
case SPECTRE_V2_USER_STRICT_PREFERRED:
return PR_SPEC_DISABLE;
default:
return PR_SPEC_NOT_AFFECTED;
@ -1002,7 +1016,8 @@ static void __init l1tf_select_mitigation(void)
#endif
half_pa = (u64)l1tf_pfn_limit() << PAGE_SHIFT;
if (e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
if (l1tf_mitigation != L1TF_MITIGATION_OFF &&
e820__mapped_any(half_pa, ULLONG_MAX - half_pa, E820_TYPE_RAM)) {
pr_warn("System has more than MAX_PA/2 memory. L1TF mitigation not effective.\n");
pr_info("You may make it effective by booting the kernel with mem=%llu parameter.\n",
half_pa);
@ -1088,6 +1103,8 @@ static char *stibp_state(void)
return ", STIBP: disabled";
case SPECTRE_V2_USER_STRICT:
return ", STIBP: forced";
case SPECTRE_V2_USER_STRICT_PREFERRED:
return ", STIBP: always-on";
case SPECTRE_V2_USER_PRCTL:
case SPECTRE_V2_USER_SECCOMP:
if (static_key_enabled(&switch_to_cond_stibp))

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@ -19,7 +19,7 @@ static inline void switch_to_extra(struct task_struct *prev,
if (IS_ENABLED(CONFIG_SMP)) {
/*
* Avoid __switch_to_xtra() invocation when conditional
* STIPB is disabled and the only different bit is
* STIBP is disabled and the only different bit is
* TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
* in the TIF_WORK_CTXSW masks.
*/

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@ -931,7 +931,7 @@ unsigned long max_swapfile_size(void)
pages = generic_max_swapfile_size();
if (boot_cpu_has_bug(X86_BUG_L1TF)) {
if (boot_cpu_has_bug(X86_BUG_L1TF) && l1tf_mitigation != L1TF_MITIGATION_OFF) {
/* Limit the swap file size to MAX_PA/2 for L1TF workaround */
unsigned long long l1tf_limit = l1tf_pfn_limit();
/*