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 <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-3-maz@kernel.org

diff --git a/arch/arm64/include/asm/stacktrace/nvhe.h b/arch/arm64/include/asm/stacktrace/nvhe.h
index 600dbc2..8a5cb96 100644 (file)
--- a/arch/arm64/include/asm/stacktrace/nvhe.h
+++ b/arch/arm64/include/asm/stacktrace/nvhe.h
@@ -172,5 +172,7 @@ static inline int notrace unwind_next(struct unwind_state *state)
 }
 NOKPROBE_SYMBOL(unwind_next);
 
+void kvm_nvhe_dump_backtrace(unsigned long hyp_offset);
+
 #endif /* __KVM_NVHE_HYPERVISOR__ */
 #endif /* __ASM_STACKTRACE_NVHE_H */

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index aa127ae..5e33c2d 100644 (file)
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -12,7 +12,7 @@ obj-$(CONFIG_KVM) += hyp/
 
 kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
         inject_fault.o va_layout.o handle_exit.o \
-        guest.o debug.o reset.o sys_regs.o \
+        guest.o debug.o reset.o sys_regs.o stacktrace.o \
         vgic-sys-reg-v3.o fpsimd.o pkvm.o \
         arch_timer.o trng.o vmid.o \
         vgic/vgic.o vgic/vgic-init.o \

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index c14fc4b..ef8b579 100644 (file)
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -319,104 +319,6 @@ void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index)
                kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu));
 }
 
-/*
- * 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 inline void kvm_nvhe_dump_backtrace_start(void)
-{
-       kvm_err("nVHE call trace:\n");
-}
-
-static inline 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.
- */
-static 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);
-}
-
 void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr,
                                              u64 elr_virt, u64 elr_phys,
                                              u64 par, uintptr_t vcpu,

diff --git a/arch/arm64/kvm/stacktrace.c b/arch/arm64/kvm/stacktrace.c
new file mode 100644 (file)
index 0000000..9812aef
--- /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 <linux/kvm.h>
+#include <linux/kvm_host.h>
+
+#include <asm/stacktrace/nvhe.h>
+
+/*
+ * 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);
+}