[PATCH v2 1/2] KVM: arm64: Dump instruction on hyp panic

[Mostafa Saleh <smostafa@google.com>]

Similar to the kernel panic, where the instruction code is printed,
we can do the same for hypervisor panics.

This patch does that only in case of “CONFIG_NVHE_EL2_DEBUG” or nvhe.

The next patch adds support for pKVM.

Also, remove the hardcoded argument dump_kernel_instr().

Signed-off-by: Mostafa Saleh <smostafa@google.com>
Tested-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: Kunwu Chan <chentao@kylinos.cn>
---
 arch/arm64/include/asm/traps.h |  1 +
 arch/arm64/kernel/traps.c      | 15 +++++++++------
 arch/arm64/kvm/handle_exit.c   |  5 +++++
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index e3e8944a71c3..e92e4a0e48fc 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -36,6 +36,7 @@ int kasan_brk_handler(struct pt_regs *regs, unsigned long esr);
 int ubsan_brk_handler(struct pt_regs *regs, unsigned long esr);
 
 int early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs);
+void dump_kernel_instr(unsigned long kaddr);
 
 /*
  * Move regs->pc to next instruction and do necessary setup before it
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index f528b6041f6a..83e6d1409e1f 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -149,19 +149,18 @@ pstate_check_t * const aarch32_opcode_cond_checks[16] = {
 
 int show_unhandled_signals = 0;
 
-static void dump_kernel_instr(const char *lvl, struct pt_regs *regs)
+void dump_kernel_instr(unsigned long kaddr)
 {
-	unsigned long addr = instruction_pointer(regs);
 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 	int i;
 
-	if (user_mode(regs))
+	if (!is_ttbr1_addr(kaddr))
 		return;
 
 	for (i = -4; i < 1; i++) {
 		unsigned int val, bad;
 
-		bad = aarch64_insn_read(&((u32 *)addr)[i], &val);
+		bad = aarch64_insn_read(&((u32 *)kaddr)[i], &val);
 
 		if (!bad)
 			p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
@@ -169,7 +168,7 @@ static void dump_kernel_instr(const char *lvl, struct pt_regs *regs)
 			p += sprintf(p, i == 0 ? "(????????) " : "???????? ");
 	}
 
-	printk("%sCode: %s\n", lvl, str);
+	printk(KERN_EMERG "Code: %s\n", str);
 }
 
 #define S_SMP " SMP"
@@ -178,6 +177,7 @@ static int __die(const char *str, long err, struct pt_regs *regs)
 {
 	static int die_counter;
 	int ret;
+	unsigned long addr = instruction_pointer(regs);
 
 	pr_emerg("Internal error: %s: %016lx [#%d] " S_SMP "\n",
 		 str, err, ++die_counter);
@@ -190,7 +190,10 @@ static int __die(const char *str, long err, struct pt_regs *regs)
 	print_modules();
 	show_regs(regs);
 
-	dump_kernel_instr(KERN_EMERG, regs);
+	if (user_mode(regs))
+		return ret;
+
+	dump_kernel_instr(addr);
 
 	return ret;
 }
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index a598072f36d2..99a8205fc104 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -559,6 +559,11 @@ void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr,
 	/* Dump the nVHE hypervisor backtrace */
 	kvm_nvhe_dump_backtrace(hyp_offset);
 
+	/* Dump the faulting instruction */
+	if (!is_protected_kvm_enabled() ||
+	    IS_ENABLED(CONFIG_NVHE_EL2_DEBUG))
+		dump_kernel_instr(panic_addr + kaslr_offset());
+
 	/*
 	 * Hyp has panicked and we're going to handle that by panicking the
 	 * kernel. The kernel offset will be revealed in the panic so we're
-- 
2.51.0.384.g4c02a37b29-goog