KVM: arm64: Move BP hardening helpers into spectre.h

The BP hardening helpers are an integral part of the Spectre-v2
mitigation, so move them into asm/spectre.h and inline the
arm64_get_bp_hardening_data() function at the same time.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20201113113847.21619-6-will@kernel.org

Author: willdeacon

arch/arm64/include/asm/mmu.h

@@ -12,9 +12,6 @@
 #define USER_ASID_FLAG	(UL(1) << USER_ASID_BIT)
 #define TTBR_ASID_MASK	(UL(0xffff) << 48)
 
-#define BP_HARDEN_EL2_SLOTS 4
-#define __BP_HARDEN_HYP_VECS_SZ (BP_HARDEN_EL2_SLOTS * SZ_2K)
-
 #ifndef __ASSEMBLY__
 
 #include <linux/refcount.h>
@@ -41,32 +38,6 @@ static inline bool arm64_kernel_unmapped_at_el0(void)
 	return cpus_have_const_cap(ARM64_UNMAP_KERNEL_AT_EL0);
 }
 
-typedef void (*bp_hardening_cb_t)(void);
-
-struct bp_hardening_data {
-	int			hyp_vectors_slot;
-	bp_hardening_cb_t	fn;
-};
-
-DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
-
-static inline struct bp_hardening_data *arm64_get_bp_hardening_data(void)
-{
-	return this_cpu_ptr(&bp_hardening_data);
-}
-
-static inline void arm64_apply_bp_hardening(void)
-{
-	struct bp_hardening_data *d;
-
-	if (!cpus_have_const_cap(ARM64_SPECTRE_V2))
-		return;
-
-	d = arm64_get_bp_hardening_data();
-	if (d->fn)
-		d->fn();
-}
-
 extern void arm64_memblock_init(void);
 extern void paging_init(void);
 extern void bootmem_init(void);

arch/arm64/include/asm/spectre.h

@@ -9,7 +9,15 @@
 #ifndef __ASM_SPECTRE_H
 #define __ASM_SPECTRE_H
 
+#define BP_HARDEN_EL2_SLOTS 4
+#define __BP_HARDEN_HYP_VECS_SZ (BP_HARDEN_EL2_SLOTS * SZ_2K)
+
+#ifndef __ASSEMBLY__
+
+#include <linux/percpu.h>
+
 #include <asm/cpufeature.h>
+#include <asm/virt.h>
 
 /* Watch out, ordering is important here. */
 enum mitigation_state {
@@ -20,6 +28,27 @@ enum mitigation_state {
 
 struct task_struct;
 
+typedef void (*bp_hardening_cb_t)(void);
+
+struct bp_hardening_data {
+	int			hyp_vectors_slot;
+	bp_hardening_cb_t	fn;
+};
+
+DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
+
+static inline void arm64_apply_bp_hardening(void)
+{
+	struct bp_hardening_data *d;
+
+	if (!cpus_have_const_cap(ARM64_SPECTRE_V2))
+		return;
+
+	d = this_cpu_ptr(&bp_hardening_data);
+	if (d->fn)
+		d->fn();
+}
+
 enum mitigation_state arm64_get_spectre_v2_state(void);
 bool has_spectre_v2(const struct arm64_cpu_capabilities *cap, int scope);
 void spectre_v2_enable_mitigation(const struct arm64_cpu_capabilities *__unused);
@@ -29,4 +58,5 @@ bool has_spectre_v4(const struct arm64_cpu_capabilities *cap, int scope);
 void spectre_v4_enable_mitigation(const struct arm64_cpu_capabilities *__unused);
 void spectre_v4_enable_task_mitigation(struct task_struct *tsk);
 
+#endif	/* __ASSEMBLY__ */
 #endif	/* __ASM_SPECTRE_H */

arch/arm64/kvm/arm.c

@@ -1405,7 +1405,7 @@ static void cpu_hyp_reset(void)
  */
 static void cpu_set_hyp_vector(void)
 {
-	struct bp_hardening_data *data = arm64_get_bp_hardening_data();
+	struct bp_hardening_data *data = this_cpu_ptr(&bp_hardening_data);
 	void *vect = kern_hyp_va(kvm_ksym_ref(__kvm_hyp_vector));
 	int slot = -1;
 

arch/arm64/kvm/hyp/hyp-entry.S

@@ -13,6 +13,7 @@
 #include <asm/kvm_arm.h>
 #include <asm/kvm_asm.h>
 #include <asm/mmu.h>
+#include <asm/spectre.h>
 
 .macro save_caller_saved_regs_vect
 	/* x0 and x1 were saved in the vector entry */