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KVM: arm64: Support per_cpu_ptr in nVHE hyp code
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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>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-14-dbrazdil@google.com
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David Brazdil authored and Marc Zyngier committed Dec 4, 2020
1 parent 2d7bf21 commit 687413d
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Showing 4 changed files with 35 additions and 1 deletion.
6 changes: 6 additions & 0 deletions arch/arm64/include/asm/percpu.h
Original file line number Diff line number Diff line change
Expand Up @@ -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. */
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3 changes: 3 additions & 0 deletions arch/arm64/kernel/image-vars.h
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Expand Up @@ -99,6 +99,9 @@ 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 */
3 changes: 2 additions & 1 deletion arch/arm64/kvm/hyp/nvhe/Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -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

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24 changes: 24 additions & 0 deletions arch/arm64/kvm/hyp/nvhe/hyp-smp.c
Original file line number Diff line number Diff line change
@@ -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;
}

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