kvm: decode data written to and read from I/O ports

With the "-e kvm=vcpu+" option, strace now decodes data written to and read
from I/O ports.

* src/kvm.c (kvm_run_structure_decode_io): Decode data written to
or read from I/O ports as a byte array.
(kvm_run_structure_decode_main): Add struct vcpu_info as a new
parameter and pass it down to kvm_run_structure_decode_io().
(kvm_run_structure_decode): Pass a struct vcpu_info object to
kvm_run_structure_decode_main.
* tests/ioctl_kvm_run_common.c (run_kvm): Allocate buffer for run_before
dynamically and copy entire mmap'ed region to the buffer.
* tests/ioctl_kvm_run_auxstr_vcpu_more.c (print_kvm_run_more): Print
data written to or read from I/O ports.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

Author: masatake

src/kvm.c

@@ -454,7 +454,7 @@ kvm_ioctl(struct tcb *const tcp, const unsigned int code, const kernel_ulong_t a
 
 static void
 kvm_run_structure_decode_io(struct tcb *tcp,
-			      struct kvm_run *state)
+			      struct kvm_run *state, struct vcpu_info *info)
 {
 	tprints_field_name("io");
 	tprint_struct_begin();
@@ -467,6 +467,18 @@ kvm_run_structure_decode_io(struct tcb *tcp,
 	PRINT_FIELD_U(state->io, count);
 	tprint_struct_next();
 	PRINT_FIELD_0X(state->io, data_offset);
+
+	if (info) {
+		unsigned long data = info->mmap_addr + state->io.data_offset;
+		unsigned long data_len = state->io.size * state->io.count;
+		unsigned char buf;
+
+		tprint_struct_next();
+		tprints_field_name("data");
+		print_array(tcp, data, data_len, &buf, sizeof(buf), tfetch_mem,
+			    print_xint_array_member, NULL);
+	}
+
 	tprint_struct_end();
 }
 
@@ -489,6 +501,7 @@ kvm_run_structure_decode_mmio(struct tcb *tcp,
 static void
 kvm_run_structure_decode_main(struct tcb *tcp,
 			      struct kvm_run *state,
+			      struct vcpu_info *info,
 			      const char *auxstr)
 {
 	tprint_struct_begin();
@@ -527,7 +540,7 @@ kvm_run_structure_decode_main(struct tcb *tcp,
 
 	switch (state->exit_reason) {
 	case KVM_EXIT_IO:
-		DECODE_UNION(kvm_run_structure_decode_io(tcp, state));
+		DECODE_UNION(kvm_run_structure_decode_io(tcp, state, info));
 		break;
 	case KVM_EXIT_MMIO:
 		DECODE_UNION(kvm_run_structure_decode_mmio(tcp, state));
@@ -552,7 +565,7 @@ kvm_run_structure_decode(struct tcb * tcp)
 			tprints_string(" VCPU< ");
 		const char *auxstr = xlookup(kvm_exit_reason,
 					     tcp->vcpu_entering->exit_reason);
-		kvm_run_structure_decode_main(tcp, tcp->vcpu_entering,
+		kvm_run_structure_decode_main(tcp, tcp->vcpu_entering, info,
 					      auxstr);
 	}
 
@@ -567,7 +580,7 @@ kvm_run_structure_decode(struct tcb * tcp)
 			tprintf_string(" VCPU:%d> ", info->cpuid);
 		else
 			tprints_string(" VCPU> ");
-		kvm_run_structure_decode_main(tcp, tcp->vcpu_leaving,
+		kvm_run_structure_decode_main(tcp, tcp->vcpu_leaving, info,
 					      tcp->auxstr);
 	}
 

tests/ioctl_kvm_run_auxstr_vcpu_more.c

@@ -36,11 +36,16 @@ print_kvm_run_more(const char *prefix, const char *reason_str, const struct kvm_
 	switch (run->exit_reason) {
 	case KVM_EXIT_IO:
 		printf(", {io={direction=%s"
-		       ", size=%u, port=%#04x, count=%u, data_offset=%#016llx}}",
+		       ", size=%u, port=%#04x, count=%u, data_offset=%#016llx",
 		       run->io.direction == KVM_EXIT_IO_IN
 		       ? "KVM_EXIT_IO_IN" : "KVM_EXIT_IO_OUT",
 		       run->io.size, run->io.port,
 		       run->io.count, run->io.data_offset);
+		fputs(", data=[", stdout);
+		for (unsigned long i = 0; i < (run->io.size * run->io.count); ++i)
+			printf("%s0x%x", i == 0?  "" : ", ",
+			       ((unsigned char *)run + run->io.data_offset)[i]);
+		fputs("]}}", stdout);
 		break;
 	case KVM_EXIT_MMIO:
 		printf(", {mmio={phys_addr=%#016llx"

tests/ioctl_kvm_run_common.c

@@ -226,10 +226,11 @@ run_kvm(const int vcpu_fd, struct kvm_run *const run, const size_t mmap_size,
 	const char *p = "\n";
 
 	/* Repeatedly run code and handle VM exits. */
+	struct kvm_run *run_before = tail_alloc(mmap_size);
 	for (;;) {
-		const struct kvm_run run_before = *run;
+		memcpy(run_before, run, mmap_size);
 		KVM_IOCTL(vcpu_fd, KVM_RUN, NULL);
-		print_KVM_RUN(vcpu_fd, vcpu_dev, &run_before, run);
+		print_KVM_RUN(vcpu_fd, vcpu_dev, run_before, run);
 
 		switch (run->exit_reason) {
 		case KVM_EXIT_HLT: