KVM: arm64: Handle calls to prefixed hyp functions

Once hyp functions are moved to a hyp object, they will have prefixed symbols.
This change declares and gets the address of the prefixed version for calls to
the hyp functions.

To aid migration, the hyp functions that have not yet moved have their prefixed
versions aliased to their non-prefixed version. This begins with all the hyp
functions being listed and will reduce to none of them once the migration is
complete.
Signed-off-by: Andrew Scull <ascull@google.com>

[David: Extracted kvm_call_hyp nVHE branches into own helper macros, added
        comments around symbol aliases.]
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-6-dbrazdil@google.com

arch/arm64/include/asm/kvm_asm.h

@@ -42,6 +42,24 @@
 
 #include <linux/mm.h>
 
+/*
+ * Translate name of a symbol defined in nVHE hyp to the name seen
+ * by kernel proper. All nVHE symbols are prefixed by the build system
+ * to avoid clashes with the VHE variants.
+ */
+#define kvm_nvhe_sym(sym)	__kvm_nvhe_##sym
+
+#define DECLARE_KVM_VHE_SYM(sym)	extern char sym[]
+#define DECLARE_KVM_NVHE_SYM(sym)	extern char kvm_nvhe_sym(sym)[]
+
+/*
+ * Define a pair of symbols sharing the same name but one defined in
+ * VHE and the other in nVHE hyp implementations.
+ */
+#define DECLARE_KVM_HYP_SYM(sym)		\
+	DECLARE_KVM_VHE_SYM(sym);		\
+	DECLARE_KVM_NVHE_SYM(sym)
+
 /* Translate a kernel address of @sym into its equivalent linear mapping */
 #define kvm_ksym_ref(sym)						\
 	({								\
@@ -50,6 +68,7 @@
 			val = lm_alias(&sym);				\
 		val;							\
 	 })
+#define kvm_ksym_ref_nvhe(sym)	kvm_ksym_ref(kvm_nvhe_sym(sym))
 
 struct kvm;
 struct kvm_vcpu;

arch/arm64/include/asm/kvm_host.h

@@ -448,6 +448,18 @@ void kvm_arm_resume_guest(struct kvm *kvm);
 
 u64 __kvm_call_hyp(void *hypfn, ...);
 
+#define kvm_call_hyp_nvhe(f, ...)					\
+	do {								\
+		DECLARE_KVM_NVHE_SYM(f);				\
+		__kvm_call_hyp(kvm_ksym_ref_nvhe(f), ##__VA_ARGS__);	\
+	} while(0)
+
+#define kvm_call_hyp_nvhe_ret(f, ...)					\
+	({								\
+		DECLARE_KVM_NVHE_SYM(f);				\
+		__kvm_call_hyp(kvm_ksym_ref_nvhe(f), ##__VA_ARGS__);	\
+	})
+
 /*
  * The couple of isb() below are there to guarantee the same behaviour
  * on VHE as on !VHE, where the eret to EL1 acts as a context
@@ -459,7 +471,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);
 			f(__VA_ARGS__);					\
 			isb();						\
 		} else {						\
-			__kvm_call_hyp(kvm_ksym_ref(f), ##__VA_ARGS__); \
+			kvm_call_hyp_nvhe(f, ##__VA_ARGS__);		\
 		}							\
 	} while(0)
 
@@ -471,8 +483,7 @@ u64 __kvm_call_hyp(void *hypfn, ...);
 			ret = f(__VA_ARGS__);				\
 			isb();						\
 		} else {						\
-			ret = __kvm_call_hyp(kvm_ksym_ref(f),		\
-					     ##__VA_ARGS__);		\
+			ret = kvm_call_hyp_nvhe_ret(f, ##__VA_ARGS__);	\
 		}							\
 									\
 		ret;							\

arch/arm64/kernel/image-vars.h

@@ -63,6 +63,32 @@ __efistub__ctype		= _ctype;
 
 #define KVM_NVHE_ALIAS(sym) __kvm_nvhe_##sym = sym;
 
+/* Symbols defined in debug-sr.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_get_mdcr_el2);
+
+/* Symbols defined in switch.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_vcpu_run_nvhe);
+
+/* Symbols defined in sysreg-sr.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_enable_ssbs);
+
+/* Symbols defined in timer-sr.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_timer_set_cntvoff);
+
+/* Symbols defined in tlb.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_flush_vm_context);
+KVM_NVHE_ALIAS(__kvm_tlb_flush_local_vmid);
+KVM_NVHE_ALIAS(__kvm_tlb_flush_vmid);
+KVM_NVHE_ALIAS(__kvm_tlb_flush_vmid_ipa);
+
+/* Symbols defined in vgic-v3-sr.c (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__vgic_v3_get_ich_vtr_el2);
+KVM_NVHE_ALIAS(__vgic_v3_init_lrs);
+KVM_NVHE_ALIAS(__vgic_v3_read_vmcr);
+KVM_NVHE_ALIAS(__vgic_v3_restore_aprs);
+KVM_NVHE_ALIAS(__vgic_v3_save_aprs);
+KVM_NVHE_ALIAS(__vgic_v3_write_vmcr);
+
 #endif /* CONFIG_KVM */
 
 #endif /* __ARM64_KERNEL_IMAGE_VARS_H */