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

[Mostafa Saleh]

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 at google.com>
---
 arch/arm64/include/asm/traps.h |  1 +
 arch/arm64/kernel/traps.c      | 20 +++++++++++++-------
 arch/arm64/kvm/handle_exit.c   |  5 +++++
 3 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 82cf1f879c61..0d7e86a95d62 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -30,6 +30,7 @@ void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *
 void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str);
 
 int early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs);
+void dump_instr(unsigned long addr);
 
 /*
  * 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 9bfa5c944379..d692c05e3686 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -149,15 +149,11 @@ 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_instr(unsigned long addr)
 {
-	unsigned long addr = instruction_pointer(regs);
 	char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 	int i;
 
-	if (user_mode(regs))
-		return;
-
 	for (i = -4; i < 1; i++) {
 		unsigned int val, bad;
 
@@ -169,7 +165,17 @@ 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);
+}
+
+static void dump_kernel_instr(struct pt_regs *regs)
+{
+	unsigned long addr = instruction_pointer(regs);
+
+	if (user_mode(regs))
+		return;
+
+	dump_instr(addr);
 }
 
 #define S_SMP " SMP"
@@ -190,7 +196,7 @@ static int __die(const char *str, long err, struct pt_regs *regs)
 	print_modules();
 	show_regs(regs);
 
-	dump_kernel_instr(KERN_EMERG, regs);
+	dump_kernel_instr(regs);
 
 	return ret;
 }
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 453266c96481..de12b4d4bccd 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -565,6 +565,11 @@ 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_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
-- 
2.50.0.727.gbf7dc18ff4-goog