x86/tdx: Add trace point for tdx fuzzer

This will allow generating coverage using the ftrace hist triggers,
and also in general is useful for understanding what happened
on a failure.

Signed-off-by: Andi Kleen <[email protected]>

Author: Andi Kleen

arch/x86/include/asm/trace/tdx.h

@@ -148,6 +148,51 @@ TRACE_EVENT(tdx_hypercall_exit,
 
 #endif // CONFIG_INTEL_TDX_GUEST
 
+#ifdef CONFIG_TDX_FUZZ
+
+TRACE_EVENT(tdx_fuzz,
+
+	TP_PROTO(u64 rip, unsigned bits, u64 oldval, u64 newval, int loc),
+
+	TP_ARGS(rip, bits, oldval, newval, loc),
+
+	TP_STRUCT__entry(
+		__field(u64, rip)
+		__field(unsigned, bits)
+		__field(u64, oldval)
+		__field(u64, newval)
+		__field(int, loc)
+	),
+
+	TP_fast_assign(
+		__entry->rip = rip;
+		__entry->bits = bits;
+		__entry->oldval = oldval;
+		__entry->newval = newval;
+		__entry->loc = loc;
+	),
+
+	TP_printk("rip %pF bits %u oldval %llx newval %llx loc %s",
+		(void *)__entry->rip,
+		__entry->bits,
+		__entry->oldval,
+		__entry->newval,
+		__print_symbolic(__entry->loc,
+				   { TDX_FUZZ_MSR_READ, "msr_read" },
+				   { TDX_FUZZ_MMIO_READ, "mmio_read" },
+				   { TDX_FUZZ_MSR_READ_ERR, "msr_read_err" },
+				   { TDX_FUZZ_MSR_WRITE_ERR, "msr_write_err" },
+				   { TDX_FUZZ_PORT_IN, "port_in" },
+				   { TDX_FUZZ_PORT_IN_ERR, "port_in_err" },
+				   { TDX_FUZZ_CPUID1, "cpuid1" },
+				   { TDX_FUZZ_CPUID2, "cpuid2" },
+				   { TDX_FUZZ_CPUID3, "cpuid3" },
+				   { TDX_FUZZ_CPUID4, "cpuid4" })
+	)
+);
+
+#endif
+
 #undef TRACE_INCLUDE_PATH
 #define TRACE_INCLUDE_PATH asm/trace/
 #undef TRACE_INCLUDE_FILE

arch/x86/kernel/tdx-fuzz.c

@@ -13,6 +13,7 @@
 #include <linux/percpu.h>
 #include <linux/smp.h>
 #include <asm/tdx.h>
+#include <asm/trace/tdx.h>
 
 static DEFINE_PER_CPU(struct rnd_state, fuzz_rndstate);
 static DECLARE_FAULT_ATTR(tdx_fault);
@@ -39,6 +40,7 @@ static u64 __tdx_fuzz(u64 var, int bits, enum tdx_fuzz_loc loc)
 		for (i = 0; i < num_bits; i++)
 			var ^= 1ULL << (rnd[i] & (bits-1));
 	}
+	trace_tdx_fuzz((u64)__builtin_return_address(0), bits, oldvar, var, loc);
 	put_cpu();
 	return var;
 }
@@ -56,6 +58,7 @@ bool tdx_fuzz_err(enum tdx_fuzz_loc loc)
 	if (!fuzz_errors || !should_fail(&tdx_fault, 1))
 		return false;
 
+	trace_tdx_fuzz((u64)__builtin_return_address(0), 1, 0, 1, loc);
 	return true;
 }