arm64: kvm: deal with kernel symbols outside of linear mapping

KVM on arm64 uses a fixed offset between the linear mapping at EL1 and
the HYP mapping at EL2. Before we can move the kernel virtual mapping
out of the linear mapping, we have to make sure that references to kernel
symbols that are accessed via the HYP mapping are translated to their
linear equivalent.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm/include/asm/kvm_asm.h b/arch/arm/include/asm/kvm_asm.h
index 194c91b610ffecfd4071da89d16b923c614bf68d..c35c349da06983b5eee05bc8bca52e526ed1bc52 100644 (file)
--- a/arch/arm/include/asm/kvm_asm.h
+++ b/arch/arm/include/asm/kvm_asm.h
@@ -79,6 +79,8 @@
 #define rr_lo_hi(a1, a2) a1, a2
 #endif
 
+#define kvm_ksym_ref(kva)      (kva)
+
 #ifndef __ASSEMBLY__
 struct kvm;
 struct kvm_vcpu;

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index dda1959f0ddeb947e8a8020d7da0b02bb19f89cc..975da6cfbf5917e604b576027189469d95cd4a52 100644 (file)
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -982,7 +982,7 @@ static void cpu_init_hyp_mode(void *dummy)
        pgd_ptr = kvm_mmu_get_httbr();
        stack_page = __this_cpu_read(kvm_arm_hyp_stack_page);
        hyp_stack_ptr = stack_page + PAGE_SIZE;
-       vector_ptr = (unsigned long)__kvm_hyp_vector;
+       vector_ptr = (unsigned long)kvm_ksym_ref(__kvm_hyp_vector);
 
        __cpu_init_hyp_mode(boot_pgd_ptr, pgd_ptr, hyp_stack_ptr, vector_ptr);
 
@@ -1074,13 +1074,15 @@ static int init_hyp_mode(void)
        /*
         * Map the Hyp-code called directly from the host
         */
-       err = create_hyp_mappings(__kvm_hyp_code_start, __kvm_hyp_code_end);
+       err = create_hyp_mappings(kvm_ksym_ref(__kvm_hyp_code_start),
+                                 kvm_ksym_ref(__kvm_hyp_code_end));
        if (err) {
                kvm_err("Cannot map world-switch code\n");
                goto out_free_mappings;
        }
 
-       err = create_hyp_mappings(__start_rodata, __end_rodata);
+       err = create_hyp_mappings(kvm_ksym_ref(__start_rodata),
+                                 kvm_ksym_ref(__end_rodata));
        if (err) {
                kvm_err("Cannot map rodata section\n");
                goto out_free_mappings;

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 52b777b7d407cfd9c2fe5036c1c7ae96bf025c0b..31b56008f412d8e61c6c4c2be7d24f2fc23136f6 100644 (file)
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -26,7 +26,24 @@
 #define KVM_ARM64_DEBUG_DIRTY_SHIFT    0
 #define KVM_ARM64_DEBUG_DIRTY          (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
 
+#define kvm_ksym_ref(sym)              ((void *)&sym + kvm_ksym_shift)
+
 #ifndef __ASSEMBLY__
+#if __GNUC__ > 4
+#define kvm_ksym_shift                 (PAGE_OFFSET - KIMAGE_VADDR)
+#else
+/*
+ * GCC versions 4.9 and older will fold the constant below into the addend of
+ * the reference to 'sym' above if kvm_ksym_shift is declared static or if the
+ * constant is used directly. However, since we use the small code model for
+ * the core kernel, the reference to 'sym' will be emitted as a adrp/add pair,
+ * with a +/- 4 GB range, resulting in linker relocation errors if the shift
+ * is sufficiently large. So prevent the compiler from folding the shift into
+ * the addend, by making the shift a variable with external linkage.
+ */
+__weak u64 kvm_ksym_shift = PAGE_OFFSET - KIMAGE_VADDR;
+#endif
+
 struct kvm;
 struct kvm_vcpu;
 

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 689d4c95e12fbd0dd7c1cf7ca9521918f37aaab0..e3d67ff8798bec6f5c773ad34c5f1edc67898d8c 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -307,7 +307,7 @@ static inline void kvm_arch_mmu_notifier_invalidate_page(struct kvm *kvm,
 struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
 
-u64 kvm_call_hyp(void *hypfn, ...);
+u64 __kvm_call_hyp(void *hypfn, ...);
 void force_vm_exit(const cpumask_t *mask);
 void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);
 
@@ -328,8 +328,8 @@ static inline void __cpu_init_hyp_mode(phys_addr_t boot_pgd_ptr,
         * Call initialization code, and switch to the full blown
         * HYP code.
         */
-       kvm_call_hyp((void *)boot_pgd_ptr, pgd_ptr,
-                    hyp_stack_ptr, vector_ptr);
+       __kvm_call_hyp((void *)boot_pgd_ptr, pgd_ptr,
+                      hyp_stack_ptr, vector_ptr);
 }
 
 static inline void kvm_arch_hardware_disable(void) {}
@@ -343,4 +343,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
 void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
 void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu);
 
+#define kvm_call_hyp(f, ...) __kvm_call_hyp(kvm_ksym_ref(f), ##__VA_ARGS__)
+
 #endif /* __ARM64_KVM_HOST_H__ */

diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 0ccdcbbef3c20ce0b4afa9874eb128cf55beb683..870578f84b1ca8940d47a9ea2a90b1600a1148e1 100644 (file)
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -20,7 +20,7 @@
 #include <asm/assembler.h>
 
 /*
- * u64 kvm_call_hyp(void *hypfn, ...);
+ * u64 __kvm_call_hyp(void *hypfn, ...);
  *
  * This is not really a variadic function in the classic C-way and care must
  * be taken when calling this to ensure parameters are passed in registers
@@ -37,7 +37,7 @@
  * used to implement __hyp_get_vectors in the same way as in
  * arch/arm64/kernel/hyp_stub.S.
  */
-ENTRY(kvm_call_hyp)
+ENTRY(__kvm_call_hyp)
        hvc     #0
        ret
-ENDPROC(kvm_call_hyp)
+ENDPROC(__kvm_call_hyp)