[PATCH v2 10/24] kvm: arm64: Support per_cpu_ptr in nVHE hyp code

David Brazdil
2020-11-16T20:44:11Z

When compiling with __KVM_NVHE_HYPERVISOR__ redefine per_cpu_offset() to
__hyp_per_cpu_offset() which looks up the base of the nVHE per-CPU
region of the given cpu and computes its offset from the
.hyp.data..percpu section.

This enables use of per_cpu_ptr() helpers in nVHE hyp code. Until now
only this_cpu_ptr() was supported by setting TPIDR_EL2.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
arch/arm64/include/asm/percpu.h | 6 ++++++
arch/arm64/kernel/image-vars.h | 3 +++
arch/arm64/kvm/hyp/nvhe/Makefile | 3 ++-
arch/arm64/kvm/hyp/nvhe/hyp-smp.c | 24 ++++++++++++++++++++++++
4 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 arch/arm64/kvm/hyp/nvhe/hyp-smp.c

diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 1599e17379d8..8f1661603b78 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -239,6 +239,12 @@ PERCPU_RET_OP(add, add, ldadd)
#define this_cpu_cmpxchg_8(pcp, o, n) \
_pcp_protect_return(cmpxchg_relaxed, pcp, o, n)

+#ifdef __KVM_NVHE_HYPERVISOR__
+extern unsigned long __hyp_per_cpu_offset(unsigned int cpu);
+#define __per_cpu_offset
+#define per_cpu_offset(cpu) __hyp_per_cpu_offset((cpu))
+#endif
+
#include <asm-generic/percpu.h>

/* Redefine macros for nVHE hyp under DEBUG_PREEMPT to avoid its dependencies. */
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index c615b285ff5b..78a42a7cdb72 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -103,6 +103,9 @@ KVM_NVHE_ALIAS(gic_nonsecure_priorities);
KVM_NVHE_ALIAS(__start___kvm_ex_table);
KVM_NVHE_ALIAS(__stop___kvm_ex_table);

+/* Array containing bases of nVHE per-CPU memory regions. */
+KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
+
#endif /* CONFIG_KVM */

#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index ddde15fe85f2..2d842e009a40 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -6,7 +6,8 @@
asflags-y := -D__KVM_NVHE_HYPERVISOR__
ccflags-y := -D__KVM_NVHE_HYPERVISOR__

-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o hyp-main.o
+obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
+ hyp-main.o hyp-smp.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-smp.c b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
new file mode 100644
index 000000000000..7b0363b4857f
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-smp.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 - Google LLC
+ * Author: David Brazdil <dbrazdil@google.com>
+ */
+
+#include <asm/kvm_asm.h>
+#include <asm/kvm_hyp.h>
+#include <asm/kvm_mmu.h>
+
+unsigned long __hyp_per_cpu_offset(unsigned int cpu)
+{
+ unsigned long *cpu_base_array;
+ unsigned long this_cpu_base;
+ unsigned long elf_base;
+
+ if (cpu >= ARRAY_SIZE(kvm_arm_hyp_percpu_base))
+ hyp_panic();
+
+ cpu_base_array = (unsigned long *)hyp_symbol_addr(kvm_arm_hyp_percpu_base);
+ this_cpu_base = kern_hyp_va(cpu_base_array[cpu]);
+ elf_base = (unsigned long)hyp_symbol_addr(__per_cpu_start);
+ return this_cpu_base - elf_base;
+}
--
2.29.2.299.gdc1121823c-goog