[PATCH v4 06/15] arm64: kvm: Build hyp-entry.S separately for VHE/nVHE

David Brazdil
2020-06-25T13:15:43Z

hyp-entry.S contains implementation of KVM hyp vectors. This code is mostly
shared between VHE/nVHE, therefore compile it under both VHE and nVHE build
rules. nVHE-specific host HVC handler is hidden behind __KVM_NVHE_HYPERVISOR__.

Adjust code which selects which KVM hyp vecs to install to choose the correct
VHE/nVHE symbol.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
arch/arm64/include/asm/kvm_asm.h | 22 +++++++++++++++++-----
arch/arm64/include/asm/mmu.h | 7 -------
arch/arm64/kernel/image-vars.h | 24 ++++++++++++++++++++++++
arch/arm64/kvm/arm.c | 2 +-
arch/arm64/kvm/hyp/Makefile | 4 ++--
arch/arm64/kvm/hyp/hyp-entry.S | 2 ++
arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
arch/arm64/kvm/hyp/vhe/Makefile | 2 +-
8 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 6a682d66a640..6026cbd204ae 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -60,12 +60,17 @@
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) \
+#define CHOOSE_VHE_SYM(sym) sym
+#define CHOOSE_NVHE_SYM(sym) kvm_nvhe_sym(sym)
+#define CHOOSE_HYP_SYM(sym) (has_vhe() ? CHOOSE_VHE_SYM(sym) \
+ : CHOOSE_NVHE_SYM(sym))
+
+/* Translate a kernel address @ptr into its equivalent linear mapping */
+#define kvm_ksym_ref(ptr) \
({ \
- void *val = &sym; \
+ void *val = (ptr); \
if (!is_kernel_in_hyp_mode()) \
- val = lm_alias(&sym); \
+ val = lm_alias((ptr)); \
val; \
})
#define kvm_ksym_ref_nvhe(sym) kvm_ksym_ref(kvm_nvhe_sym(sym))
@@ -76,7 +81,14 @@ struct kvm_vcpu;
extern char __kvm_hyp_init[];
extern char __kvm_hyp_init_end[];

-extern char __kvm_hyp_vector[];
+DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
+#define __kvm_hyp_vector CHOOSE_HYP_SYM(__kvm_hyp_vector)
+
+#ifdef CONFIG_KVM_INDIRECT_VECTORS
+extern atomic_t arm64_el2_vector_last_slot;
+DECLARE_KVM_HYP_SYM(__bp_harden_hyp_vecs);
+#define __bp_harden_hyp_vecs CHOOSE_HYP_SYM(__bp_harden_hyp_vecs)
+#endif

extern void __kvm_flush_vm_context(void);
extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 68140fdd89d6..4d913f6dd366 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -42,13 +42,6 @@ struct bp_hardening_data {
bp_hardening_cb_t fn;
};

-#if (defined(CONFIG_HARDEN_BRANCH_PREDICTOR) || \
- defined(CONFIG_HARDEN_EL2_VECTORS))
-
-extern char __bp_harden_hyp_vecs[];
-extern atomic_t arm64_el2_vector_last_slot;
-#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR || CONFIG_HARDEN_EL2_VECTORS */
-
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
DECLARE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);

diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 36444bac6a05..f28da486b75a 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -66,8 +66,17 @@ __efistub__ctype = _ctype;
/* Symbols defined in debug-sr.c (not yet compiled with nVHE build rules). */
KVM_NVHE_ALIAS(__kvm_get_mdcr_el2);

+/* Symbols defined in entry.S (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__guest_exit);
+KVM_NVHE_ALIAS(abort_guest_exit_end);
+KVM_NVHE_ALIAS(abort_guest_exit_start);
+
+/* Symbols defined in hyp-init.S (not yet compiled with nVHE build rules). */
+KVM_NVHE_ALIAS(__kvm_handle_stub_hvc);
+
/* Symbols defined in switch.c (not yet compiled with nVHE build rules). */
KVM_NVHE_ALIAS(__kvm_vcpu_run_nvhe);
+KVM_NVHE_ALIAS(hyp_panic);

/* Symbols defined in sysreg-sr.c (not yet compiled with nVHE build rules). */
KVM_NVHE_ALIAS(__kvm_enable_ssbs);
@@ -89,6 +98,21 @@ KVM_NVHE_ALIAS(__vgic_v3_restore_aprs);
KVM_NVHE_ALIAS(__vgic_v3_save_aprs);
KVM_NVHE_ALIAS(__vgic_v3_write_vmcr);

+/* Alternative callbacks for init-time patching of nVHE hyp code. */
+KVM_NVHE_ALIAS(arm64_enable_wa2_handling);
+KVM_NVHE_ALIAS(kvm_patch_vector_branch);
+KVM_NVHE_ALIAS(kvm_update_va_mask);
+
+/* Global kernel state accessed by nVHE hyp code. */
+KVM_NVHE_ALIAS(arm64_ssbd_callback_required);
+KVM_NVHE_ALIAS(kvm_host_data);
+
+/* Kernel constant needed to compute idmap addresses. */
+KVM_NVHE_ALIAS(kimage_voffset);
+
+/* Kernel symbols used to call panic() from nVHE hyp code (via ERET). */
+KVM_NVHE_ALIAS(panic);
+
#endif /* CONFIG_KVM */

#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 90cb90561446..34b551385153 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1285,7 +1285,7 @@ static void cpu_init_hyp_mode(void)
* so that we can use adr_l to access per-cpu variables in EL2.
*/
tpidr_el2 = ((unsigned long)this_cpu_ptr(&kvm_host_data) -
- (unsigned long)kvm_ksym_ref(kvm_host_data));
+ (unsigned long)kvm_ksym_ref(&kvm_host_data));

pgd_ptr = kvm_mmu_get_httbr();
hyp_stack_ptr = __this_cpu_read(kvm_arm_hyp_stack_page) + PAGE_SIZE;
diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 9c5dfe6ff80b..8b0cf85080b5 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile
@@ -10,11 +10,11 @@ subdir-ccflags-y := -I$(incdir) \
-DDISABLE_BRANCH_PROFILING \
$(DISABLE_STACKLEAK_PLUGIN)

-obj-$(CONFIG_KVM) += hyp.o nvhe/
+obj-$(CONFIG_KVM) += hyp.o vhe/ nvhe/
obj-$(CONFIG_KVM_INDIRECT_VECTORS) += smccc_wa.o

hyp-y := vgic-v3-sr.o timer-sr.o aarch32.o vgic-v2-cpuif-proxy.o sysreg-sr.o \
- debug-sr.o entry.o switch.o fpsimd.o tlb.o hyp-entry.o
+ debug-sr.o entry.o switch.o fpsimd.o tlb.o

# KVM code is run at a different exception code with a different map, so
# compiler instrumentation that inserts callbacks or checks into the code may
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index d362fad97cc8..7e3c72fa634f 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -40,6 +40,7 @@ el1_sync: // Guest trapped into EL2
ccmp x0, #ESR_ELx_EC_HVC32, #4, ne
b.ne el1_trap

+#ifdef __KVM_NVHE_HYPERVISOR__
mrs x1, vttbr_el2 // If vttbr is valid, the guest
cbnz x1, el1_hvc_guest // called HVC

@@ -74,6 +75,7 @@ el1_sync: // Guest trapped into EL2

eret
sb
+#endif /* __KVM_NVHE_HYPERVISOR__ */

el1_hvc_guest:
/*
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 955f4188e00f..79eb8eed96a1 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -6,7 +6,7 @@
asflags-y := -D__KVM_NVHE_HYPERVISOR__
ccflags-y := -D__KVM_NVHE_HYPERVISOR__

-obj-y :=
+obj-y := ../hyp-entry.o

obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
diff --git a/arch/arm64/kvm/hyp/vhe/Makefile b/arch/arm64/kvm/hyp/vhe/Makefile
index e04375546081..323029e02b4e 100644
--- a/arch/arm64/kvm/hyp/vhe/Makefile
+++ b/arch/arm64/kvm/hyp/vhe/Makefile
@@ -6,7 +6,7 @@
asflags-y := -D__KVM_VHE_HYPERVISOR__
ccflags-y := -D__KVM_VHE_HYPERVISOR__

-obj-y :=
+obj-y := ../hyp-entry.o

# KVM code is run at a different exception code with a different map, so
# compiler instrumentation that inserts callbacks or checks into the code may
--
2.27.0