[PATCH 05/15] arm64: kvm: Build hyp-entry.S separately for VHE/nVHE

David Brazdil
2020-04-30T14:49:00Z

This patch is part of a series which builds KVM's non-VHE hyp code separately
from VHE and the rest of the kernel.

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, with small differences hidden behind '#ifdef __HYPERVISOR__'. These are:
* only nVHE should handle host HVCs, VHE will now panic,
* only nVHE needs kvm_hcall_table, so move host_hypcall.c to nvhe/,
* __smccc_workaround_1_smc is not needed by nVHE, only cpu_errata.c in
kernel proper.

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 | 7 +++++
arch/arm64/include/asm/kvm_mmu.h | 13 +++++----
arch/arm64/include/asm/mmu.h | 7 -----
arch/arm64/kernel/cpu_errata.c | 2 +-
arch/arm64/kernel/image-vars.h | 28 +++++++++++++++++++
arch/arm64/kvm/hyp/Makefile | 2 +-
arch/arm64/kvm/hyp/hyp-entry.S | 27 ++++++++++++------
arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
.../arm64/kvm/hyp/{ => nvhe}/host_hypercall.c | 0
arch/arm64/kvm/va_layout.c | 2 +-
10 files changed, 65 insertions(+), 25 deletions(-)
rename arch/arm64/kvm/hyp/{ => nvhe}/host_hypercall.c (100%)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 99ab204519ca..cdaf3df8085d 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -71,6 +71,13 @@ extern char __kvm_hyp_init[];
extern char __kvm_hyp_init_end[];

extern char __kvm_hyp_vector[];
+extern char kvm_nvhe_sym(__kvm_hyp_vector)[];
+
+#ifdef CONFIG_KVM_INDIRECT_VECTORS
+extern char __bp_harden_hyp_vecs[];
+extern char kvm_nvhe_sym(__bp_harden_hyp_vecs)[];
+extern atomic_t arm64_el2_vector_last_slot;
+#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/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index 30b0e8d6b895..0a5fa033422c 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -468,7 +468,7 @@ static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
* VHE, as we don't have hypervisor-specific mappings. If the system
* is VHE and yet selects this capability, it will be ignored.
*/
-#include <asm/mmu.h>
+#include <asm/kvm_asm.h>

extern void *__kvm_bp_vect_base;
extern int __kvm_harden_el2_vector_slot;
@@ -477,11 +477,11 @@ extern int __kvm_harden_el2_vector_slot;
static inline void *kvm_get_hyp_vector(void)
{
struct bp_hardening_data *data = arm64_get_bp_hardening_data();
- void *vect = kern_hyp_va(kvm_ksym_ref(__kvm_hyp_vector));
+ void *vect = kern_hyp_va(kvm_hyp_ref(__kvm_hyp_vector));
int slot = -1;

if (cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR) && data->fn) {
- vect = kern_hyp_va(kvm_ksym_ref(__bp_harden_hyp_vecs));
+ vect = kern_hyp_va(kvm_hyp_ref(__bp_harden_hyp_vecs));
slot = data->hyp_vectors_slot;
}

@@ -510,12 +510,13 @@ static inline int kvm_map_vectors(void)
* HBP + HEL2 -> use hardened vertors and use exec mapping
*/
if (cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR)) {
- __kvm_bp_vect_base = kvm_ksym_ref(__bp_harden_hyp_vecs);
+ __kvm_bp_vect_base = kvm_hyp_ref(__bp_harden_hyp_vecs);
__kvm_bp_vect_base = kern_hyp_va(__kvm_bp_vect_base);
}

if (cpus_have_const_cap(ARM64_HARDEN_EL2_VECTORS)) {
- phys_addr_t vect_pa = __pa_symbol(__bp_harden_hyp_vecs);
+ phys_addr_t vect_pa =
+ __pa_symbol(kvm_nvhe_sym(__bp_harden_hyp_vecs));
unsigned long size = __BP_HARDEN_HYP_VECS_SZ;

/*
@@ -534,7 +535,7 @@ static inline int kvm_map_vectors(void)
#else
static inline void *kvm_get_hyp_vector(void)
{
- return kern_hyp_va(kvm_ksym_ref(__kvm_hyp_vector));
+ return kern_hyp_va(kvm_hyp_ref(__kvm_hyp_vector));
}

static inline int kvm_map_vectors(void)
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/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index a102321fc8a2..b4b41552c6df 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -117,7 +117,7 @@ DEFINE_PER_CPU_READ_MOSTLY(struct bp_hardening_data, bp_hardening_data);
static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start,
const char *hyp_vecs_end)
{
- void *dst = lm_alias(__bp_harden_hyp_vecs + slot * SZ_2K);
+ void *dst = lm_alias(kvm_hyp_sym(__bp_harden_hyp_vecs) + slot * SZ_2K);
int i;

for (i = 0; i < SZ_2K; i += 0x80)
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 13850134fc28..59c53566eceb 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -61,6 +61,34 @@ __efistub__ctype = _ctype;
* memory mappings.
*/

+__hyp_text___guest_exit = __guest_exit;
+__hyp_text___kvm_enable_ssbs = __kvm_enable_ssbs;
+__hyp_text___kvm_flush_vm_context = __kvm_flush_vm_context;
+__hyp_text___kvm_get_mdcr_el2 = __kvm_get_mdcr_el2;
+__hyp_text___kvm_handle_stub_hvc = __kvm_handle_stub_hvc;
+__hyp_text___kvm_timer_set_cntvoff = __kvm_timer_set_cntvoff;
+__hyp_text___kvm_tlb_flush_local_vmid = __kvm_tlb_flush_local_vmid;
+__hyp_text___kvm_tlb_flush_vmid = __kvm_tlb_flush_vmid;
+__hyp_text___kvm_tlb_flush_vmid_ipa = __kvm_tlb_flush_vmid_ipa;
+__hyp_text___kvm_vcpu_run_nvhe = __kvm_vcpu_run_nvhe;
+__hyp_text___vgic_v3_get_ich_vtr_el2 = __vgic_v3_get_ich_vtr_el2;
+__hyp_text___vgic_v3_init_lrs = __vgic_v3_init_lrs;
+__hyp_text___vgic_v3_read_vmcr = __vgic_v3_read_vmcr;
+__hyp_text___vgic_v3_restore_aprs = __vgic_v3_restore_aprs;
+__hyp_text___vgic_v3_save_aprs = __vgic_v3_save_aprs;
+__hyp_text___vgic_v3_write_vmcr = __vgic_v3_write_vmcr;
+__hyp_text_abort_guest_exit_end = abort_guest_exit_end;
+__hyp_text_abort_guest_exit_start = abort_guest_exit_start;
+__hyp_text_arm64_enable_wa2_handling = arm64_enable_wa2_handling;
+__hyp_text_arm64_ssbd_callback_required = arm64_ssbd_callback_required;
+__hyp_text_hyp_panic = hyp_panic;
+__hyp_text_kimage_voffset = kimage_voffset;
+__hyp_text_kvm_host_data = kvm_host_data;
+__hyp_text_kvm_patch_vector_branch = kvm_patch_vector_branch;
+__hyp_text_kvm_update_va_mask = kvm_update_va_mask;
+__hyp_text_panic = panic;
+__hyp_text_physvirt_offset = physvirt_offset;
+
#endif /* CONFIG_KVM */

#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
index 79bf822a484b..a6883f4fed9e 100644
--- a/arch/arm64/kvm/hyp/Makefile
+++ b/arch/arm64/kvm/hyp/Makefile
@@ -9,7 +9,7 @@ ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \
obj-$(CONFIG_KVM) += vhe.o nvhe/

vhe-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 host_hypercall.o hyp-entry.o
+ debug-sr.o entry.o switch.o fpsimd.o tlb.o 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
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 1a51a0958504..5986e1d78d3f 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -36,12 +36,6 @@
ldr lr, [sp], #16
.endm

-/* kern_hyp_va(lm_alias(ksym)) */
-.macro ksym_hyp_va ksym, lm_offset
- sub \ksym, \ksym, \lm_offset
- kern_hyp_va \ksym
-.endm
-
el1_sync: // Guest trapped into EL2

mrs x0, esr_el2
@@ -53,7 +47,15 @@ el1_sync: // Guest trapped into EL2
mrs x1, vttbr_el2 // If vttbr is valid, the guest
cbnz x1, el1_hvc_guest // called HVC

- /* Here, we're pretty sure the host called HVC. */
+#ifdef __HYPERVISOR__
+
+/* kern_hyp_va(lm_alias(ksym)) */
+.macro ksym_hyp_va ksym, lm_offset
+ sub \ksym, \ksym, \lm_offset
+ kern_hyp_va \ksym
+.endm
+
+ /* nVHE: Here, we're pretty sure the host called HVC. */
ldp x0, x1, [sp], #16

/* Check for a stub HVC call */
@@ -107,6 +109,13 @@ el1_sync: // Guest trapped into EL2
eret
sb

+#else /* __HYPERVISOR__ */
+
+ /* VHE: Guest called HVC but vttbr is not valid. */
+ b __hyp_panic
+
+#endif /* __HYPERVISOR__ */
+
el1_hvc_guest:
/*
* Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.
@@ -354,6 +363,7 @@ SYM_CODE_END(__bp_harden_hyp_vecs)

.popsection

+#ifndef __HYPERVISOR__
SYM_CODE_START(__smccc_workaround_1_smc)
esb
sub sp, sp, #(8 * 4)
@@ -367,4 +377,5 @@ SYM_CODE_START(__smccc_workaround_1_smc)
1: .org __smccc_workaround_1_smc + __SMCCC_WORKAROUND_1_SMC_SZ
.org 1b
SYM_CODE_END(__smccc_workaround_1_smc)
-#endif
+#endif /* __HYPERVISOR__ */
+#endif /* CONFIG_KVM_INDIRECT_VECTORS */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 873d3ab0fd68..fa20b2723652 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -7,7 +7,7 @@ asflags-y := -D__HYPERVISOR__
ccflags-y := -D__HYPERVISOR__ -fno-stack-protector -DDISABLE_BRANCH_PROFILING \
$(DISABLE_STACKLEAK_PLUGIN)

-obj-y :=
+obj-y := host_hypercall.o ../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/host_hypercall.c b/arch/arm64/kvm/hyp/nvhe/host_hypercall.c
similarity index 100%
rename from arch/arm64/kvm/hyp/host_hypercall.c
rename to arch/arm64/kvm/hyp/nvhe/host_hypercall.c
diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index a4f48c1ac28c..8d941d19085d 100644
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -150,7 +150,7 @@ void kvm_patch_vector_branch(struct alt_instr *alt,
/*
* Compute HYP VA by using the same computation as kern_hyp_va()
*/
- addr = (uintptr_t)kvm_ksym_ref(__kvm_hyp_vector);
+ addr = (uintptr_t)kvm_hyp_ref(__kvm_hyp_vector);
addr &= va_mask;
addr |= tag_val << tag_lsb;

--
2.26.1