Commit 9f5fee05 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

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: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarKalesh Singh <kaleshsingh@google.com>
Tested-by: default avatarKalesh Singh <kaleshsingh@google.com>
Reviewed-by: default avatarOliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-3-maz@kernel.org
parent 03fe9cd0

arch/arm64/include/asm/stacktrace/nvhe.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/kvm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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 \

arch/arm64/kvm/handle_exit.c

+0 −98
Original line number Diff line number Diff line
@@ -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,

arch/arm64/kvm/stacktrace.c

0 → 100644
+120 −0
Original line number Diff line number Diff line 
/* 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);

}