Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Merge speculative store buffer bypass fixes from Thomas Gleixner:

 - rework of the SPEC_CTRL MSR management to accomodate the new fancy
   SSBD (Speculative Store Bypass Disable) bit handling.

 - the CPU bug and sysfs infrastructure for the exciting new Speculative
   Store Bypass 'feature'.

 - support for disabling SSB via LS_CFG MSR on AMD CPUs including
   Hyperthread synchronization on ZEN.

 - PRCTL support for dynamic runtime control of SSB

 - SECCOMP integration to automatically disable SSB for sandboxed
   processes with a filter flag for opt-out.

 - KVM integration to allow guests fiddling with SSBD including the new
   software MSR VIRT_SPEC_CTRL to handle the LS_CFG based oddities on
   AMD.

 - BPF protection against SSB

.. this is just the core and x86 side, other architecture support will
come separately.

* 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits)
  bpf: Prevent memory disambiguation attack
  x86/bugs: Rename SSBD_NO to SSB_NO
  KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
  x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
  x86/bugs: Rework spec_ctrl base and mask logic
  x86/bugs: Remove x86_spec_ctrl_set()
  x86/bugs: Expose x86_spec_ctrl_base directly
  x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
  x86/speculation: Rework speculative_store_bypass_update()
  x86/speculation: Add virtualized speculative store bypass disable support
  x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
  x86/speculation: Handle HT correctly on AMD
  x86/cpufeatures: Add FEATURE_ZEN
  x86/cpufeatures: Disentangle SSBD enumeration
  x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
  x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
  KVM: SVM: Move spec control call after restore of GS
  x86/cpu: Make alternative_msr_write work for 32-bit code
  x86/bugs: Fix the parameters alignment and missing void
  x86/bugs: Make cpu_show_common() static
  ...

7 files changed, 40 insertions, 5 deletions

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 7e61c395fddf..65cfc2f59db9 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -146,6 +146,7 @@ struct bpf_insn_aux_data {
 		s32 call_imm;			/* saved imm field of call insn */
 	};
 	int ctx_field_size; /* the ctx field size for load insn, maybe 0 */
+	int sanitize_stack_off; /* stack slot to be cleared */
 	bool seen; /* this insn was processed by the verifier */
 };
 
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 7b01bc11c692..a97a63eef59f 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -53,6 +53,8 @@ extern ssize_t cpu_show_spectre_v1(struct device *dev,
 				   struct device_attribute *attr, char *buf);
 extern ssize_t cpu_show_spectre_v2(struct device *dev,
 				   struct device_attribute *attr, char *buf);
+extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
+					  struct device_attribute *attr, char *buf);
 
 extern __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,
diff --git a/include/linux/nospec.h b/include/linux/nospec.h
index e791ebc65c9c..0c5ef54fd416 100644
--- a/include/linux/nospec.h
+++ b/include/linux/nospec.h
@@ -7,6 +7,8 @@
 #define _LINUX_NOSPEC_H
 #include <asm/barrier.h>
 
+struct task_struct;
+
 /**
  * array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise
  * @index: array element index
@@ -55,4 +57,12 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,
 									\
 	(typeof(_i)) (_i & _mask);					\
 })
+
+/* Speculation control prctl */
+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which);
+int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which,
+			     unsigned long ctrl);
+/* Speculation control for seccomp enforced mitigation */
+void arch_seccomp_spec_mitigate(struct task_struct *task);
+
 #endif /* _LINUX_NOSPEC_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c2413703f45d..ca3f3eae8980 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1433,7 +1433,8 @@ static inline bool is_percpu_thread(void)
 #define PFA_NO_NEW_PRIVS		0	/* May not gain new privileges. */
 #define PFA_SPREAD_PAGE			1	/* Spread page cache over cpuset */
 #define PFA_SPREAD_SLAB			2	/* Spread some slab caches over cpuset */
-
+#define PFA_SPEC_SSB_DISABLE		3	/* Speculative Store Bypass disabled */
+#define PFA_SPEC_SSB_FORCE_DISABLE	4	/* Speculative Store Bypass force disabled*/
 
 #define TASK_PFA_TEST(name, func)					\
 	static inline bool task_##func(struct task_struct *p)		\
@@ -1458,6 +1459,13 @@ TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
 TASK_PFA_SET(SPREAD_SLAB, spread_slab)
 TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
 
+TASK_PFA_TEST(SPEC_SSB_DISABLE, spec_ssb_disable)
+TASK_PFA_SET(SPEC_SSB_DISABLE, spec_ssb_disable)
+TASK_PFA_CLEAR(SPEC_SSB_DISABLE, spec_ssb_disable)
+
+TASK_PFA_TEST(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
+TASK_PFA_SET(SPEC_SSB_FORCE_DISABLE, spec_ssb_force_disable)
+
 static inline void
 current_restore_flags(unsigned long orig_flags, unsigned long flags)
 {
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index c723a5c4e3ff..e5320f6c8654 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -4,8 +4,9 @@
 
 #include <uapi/linux/seccomp.h>
 
-#define SECCOMP_FILTER_FLAG_MASK	(SECCOMP_FILTER_FLAG_TSYNC | \
-					 SECCOMP_FILTER_FLAG_LOG)
+#define SECCOMP_FILTER_FLAG_MASK	(SECCOMP_FILTER_FLAG_TSYNC	| \
+					 SECCOMP_FILTER_FLAG_LOG	| \
+					 SECCOMP_FILTER_FLAG_SPEC_ALLOW)
 
 #ifdef CONFIG_SECCOMP
 
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index af5f8c2df87a..db9f15f5db04 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -207,4 +207,16 @@ struct prctl_mm_map {
 # define PR_SVE_VL_LEN_MASK		0xffff
 # define PR_SVE_VL_INHERIT		(1 << 17) /* inherit across exec */
 
+/* Per task speculation control */
+#define PR_GET_SPECULATION_CTRL		52
+#define PR_SET_SPECULATION_CTRL		53
+/* Speculation control variants */
+# define PR_SPEC_STORE_BYPASS		0
+/* Return and control values for PR_SET/GET_SPECULATION_CTRL */
+# define PR_SPEC_NOT_AFFECTED		0
+# define PR_SPEC_PRCTL			(1UL << 0)
+# define PR_SPEC_ENABLE			(1UL << 1)
+# define PR_SPEC_DISABLE		(1UL << 2)
+# define PR_SPEC_FORCE_DISABLE		(1UL << 3)
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/include/uapi/linux/seccomp.h b/include/uapi/linux/seccomp.h
index 2a0bd9dd104d..9efc0e73d50b 100644
--- a/include/uapi/linux/seccomp.h
+++ b/include/uapi/linux/seccomp.h
@@ -17,8 +17,9 @@
 #define SECCOMP_GET_ACTION_AVAIL	2
 
 /* Valid flags for SECCOMP_SET_MODE_FILTER */
-#define SECCOMP_FILTER_FLAG_TSYNC	1
-#define SECCOMP_FILTER_FLAG_LOG		2
+#define SECCOMP_FILTER_FLAG_TSYNC	(1UL << 0)
+#define SECCOMP_FILTER_FLAG_LOG		(1UL << 1)
+#define SECCOMP_FILTER_FLAG_SPEC_ALLOW	(1UL << 2)
 
 /*
  * All BPF programs must return a 32-bit value.