From 9f5fee05f6897d0fe0e3a44ade71bb85cd97b2ef Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Wed, 27 Jul 2022 15:29:02 +0100 Subject: KVM: arm64: Move nVHE stacktrace unwinding into its own compilation unit The unwinding code doesn't really belong to the exit handling code. Instead, move it to a file (conveniently named stacktrace.c to confuse the reviewer), and move all the stacktrace-related stuff there. It will be joined by more code very soon. Signed-off-by: Marc Zyngier Reviewed-by: Kalesh Singh Tested-by: Kalesh Singh Reviewed-by: Oliver Upton Link: https://lore.kernel.org/r/20220727142906.1856759-3-maz@kernel.org --- arch/arm64/kvm/stacktrace.c | 120 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 120 insertions(+) create mode 100644 arch/arm64/kvm/stacktrace.c (limited to 'arch/arm64/kvm/stacktrace.c') diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c new file mode 100644 index 000000000000..9812aefdcfb4 --- /dev/null +++ b/arch/arm64/kvm/stacktrace.c @@ -0,0 +1,120 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * KVM nVHE hypervisor stack tracing support. + * + * The unwinder implementation depends on the nVHE mode: + * + * 1) Non-protected nVHE mode - the host can directly access the + * HYP stack pages and unwind the HYP stack in EL1. This saves having + * to allocate shared buffers for the host to read the unwinded + * stacktrace. + * + * 2) pKVM (protected nVHE) mode - the host cannot directly access + * the HYP memory. The stack is unwinded in EL2 and dumped to a shared + * buffer where the host can read and print the stacktrace. + * + * Copyright (C) 2022 Google LLC + */ + +#include +#include + +#include + +/* + * kvm_nvhe_dump_backtrace_entry - Symbolize and print an nVHE backtrace entry + * + * @arg : the hypervisor offset, used for address translation + * @where : the program counter corresponding to the stack frame + */ +static bool kvm_nvhe_dump_backtrace_entry(void *arg, unsigned long where) +{ + unsigned long va_mask = GENMASK_ULL(vabits_actual - 1, 0); + unsigned long hyp_offset = (unsigned long)arg; + + /* Mask tags and convert to kern addr */ + where = (where & va_mask) + hyp_offset; + kvm_err(" [<%016lx>] %pB\n", where, (void *)(where + kaslr_offset())); + + return true; +} + +static void kvm_nvhe_dump_backtrace_start(void) +{ + kvm_err("nVHE call trace:\n"); +} + +static void kvm_nvhe_dump_backtrace_end(void) +{ + kvm_err("---[ end nVHE call trace ]---\n"); +} + +/* + * hyp_dump_backtrace - Dump the non-protected nVHE backtrace. + * + * @hyp_offset: hypervisor offset, used for address translation. + * + * The host can directly access HYP stack pages in non-protected + * mode, so the unwinding is done directly from EL1. This removes + * the need for shared buffers between host and hypervisor for + * the stacktrace. + */ +static void hyp_dump_backtrace(unsigned long hyp_offset) +{ + struct kvm_nvhe_stacktrace_info *stacktrace_info; + struct unwind_state state; + + stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info); + + kvm_nvhe_unwind_init(&state, stacktrace_info->fp, stacktrace_info->pc); + + kvm_nvhe_dump_backtrace_start(); + unwind(&state, kvm_nvhe_dump_backtrace_entry, (void *)hyp_offset); + kvm_nvhe_dump_backtrace_end(); +} + +#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE +DECLARE_KVM_NVHE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], + pkvm_stacktrace); + +/* + * pkvm_dump_backtrace - Dump the protected nVHE HYP backtrace. + * + * @hyp_offset: hypervisor offset, used for address translation. + * + * Dumping of the pKVM HYP backtrace is done by reading the + * stack addresses from the shared stacktrace buffer, since the + * host cannot directly access hypervisor memory in protected + * mode. + */ +static void pkvm_dump_backtrace(unsigned long hyp_offset) +{ + unsigned long *stacktrace + = (unsigned long *) this_cpu_ptr_nvhe_sym(pkvm_stacktrace); + int i, size = NVHE_STACKTRACE_SIZE / sizeof(long); + + kvm_nvhe_dump_backtrace_start(); + /* The saved stacktrace is terminated by a null entry */ + for (i = 0; i < size && stacktrace[i]; i++) + kvm_nvhe_dump_backtrace_entry((void *)hyp_offset, stacktrace[i]); + kvm_nvhe_dump_backtrace_end(); +} +#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */ +static void pkvm_dump_backtrace(unsigned long hyp_offset) +{ + kvm_err("Cannot dump pKVM nVHE stacktrace: !CONFIG_PROTECTED_NVHE_STACKTRACE\n"); +} +#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */ + +/* + * kvm_nvhe_dump_backtrace - Dump KVM nVHE hypervisor backtrace. + * + * @hyp_offset: hypervisor offset, used for address translation. + */ +void kvm_nvhe_dump_backtrace(unsigned long hyp_offset) +{ + if (is_protected_kvm_enabled()) + pkvm_dump_backtrace(hyp_offset); + else + hyp_dump_backtrace(hyp_offset); +} -- cgit v1.2.3-59-g8ed1b