kvm tools: Allow remapping guest TTY into host PTS

This patch adds the '-tty' option to 'kvm run' which allows the user to
remap a guest TTY into a PTS on the host.

Usage:
        'kvm run --tty [id]'

The tty will be mapped to a pts and will be printed on the screen:
        '  Info: Assigned terminal 1 to pty /dev/pts/X'

At this point, it is possible to communicate with the guest using that pty.

This is useful for debugging guest kernel using KGDB:

1. Run the guest:
        'kvm run -k [vmlinuz] -p "kgdboc=ttyS1 kgdbwait" --tty 1'

And see which PTY got assigned to ttyS1.

2. Run GDB on the host:
        'gdb [vmlinuz]'

3. Connect to the guest (from within GDB):
        'target remote /dev/pty/X'

4. Start debugging! (enter 'continue' to continue boot).

Cc: David Evensky <evensky@dancer.ca.sandia.gov>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index efa032d6ad9de39f8634c07c9444ce37f8fb93af..fef624dfa351a91227e7dd35abdca31ecef483b0 100644 (file)
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -115,6 +115,7 @@ OBJS        += bios/bios-rom.o
 
 LIBS   += -lrt
 LIBS   += -lpthread
+LIBS   += -lutil
 
 # Additional ARCH settings for x86
 ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \

diff --git a/tools/kvm/builtin-run.c b/tools/kvm/builtin-run.c
index 5dafb15b429b6550acdcf29fab5ea82666218a23..b5c63cab2e7b05da4434be634495dccd8adfc394 100644 (file)
--- a/tools/kvm/builtin-run.c
+++ b/tools/kvm/builtin-run.c
@@ -172,6 +172,15 @@ static int virtio_9p_rootdir_parser(const struct option *opt, const char *arg, i
        return 0;
 }
 
+static int tty_parser(const struct option *opt, const char *arg, int unset)
+{
+       int tty = atoi(arg);
+
+       term_set_tty(tty);
+
+       return 0;
+}
+
 static int shmem_parser(const struct option *opt, const char *arg, int unset)
 {
        const u64 default_size = SHMEM_DEFAULT_SIZE;
@@ -316,6 +325,9 @@ static const struct option options[] = {
        OPT_STRING('\0', "console", &console, "serial or virtio",
                        "Console to use"),
        OPT_STRING('\0', "dev", &dev, "device_file", "KVM device file"),
+       OPT_CALLBACK('\0', "tty", NULL, "tty id",
+                    "Remap guest TTY into a pty on the host",
+                    tty_parser),
 
        OPT_GROUP("Kernel options:"),
        OPT_STRING('k', "kernel", &kernel_filename, "kernel",

diff --git a/tools/kvm/hw/serial.c b/tools/kvm/hw/serial.c
index b3b233ff186a9f32949e6b9bae6ab4b77683e29d..11fa5d47df3611610ed83971b24f8a5dff37ed1e 100644 (file)
--- a/tools/kvm/hw/serial.c
+++ b/tools/kvm/hw/serial.c
@@ -14,6 +14,7 @@
 
 struct serial8250_device {
        pthread_mutex_t         mutex;
+       u8                      id;
 
        u16                     iobase;
        u8                      irq;
@@ -42,6 +43,7 @@ static struct serial8250_device devices[] = {
        [0]     = {
                .mutex                  = PTHREAD_MUTEX_INITIALIZER,
 
+               .id                     = 0,
                .iobase                 = 0x3f8,
                .irq                    = 4,
 
@@ -51,6 +53,7 @@ static struct serial8250_device devices[] = {
        [1]     = {
                .mutex                  = PTHREAD_MUTEX_INITIALIZER,
 
+               .id                     = 1,
                .iobase                 = 0x2f8,
                .irq                    = 3,
 
@@ -60,6 +63,7 @@ static struct serial8250_device devices[] = {
        [2]     = {
                .mutex                  = PTHREAD_MUTEX_INITIALIZER,
 
+               .id                     = 2,
                .iobase                 = 0x3e8,
                .irq                    = 4,
 
@@ -69,6 +73,7 @@ static struct serial8250_device devices[] = {
        [3]     = {
                .mutex                  = PTHREAD_MUTEX_INITIALIZER,
 
+               .id                     = 3,
                .iobase                 = 0x2e8,
                .irq                    = 3,
 
@@ -111,10 +116,10 @@ static void serial8250__receive(struct kvm *kvm, struct serial8250_device *dev)
                return;
        }
 
-       if (!term_readable(CONSOLE_8250))
+       if (!term_readable(CONSOLE_8250, dev->id))
                return;
 
-       c               = term_getc(CONSOLE_8250);
+       c = term_getc(CONSOLE_8250, dev->id);
 
        if (c < 0)
                return;
@@ -123,30 +128,31 @@ static void serial8250__receive(struct kvm *kvm, struct serial8250_device *dev)
        dev->lsr        |= UART_LSR_DR;
 }
 
-/*
- * Interrupts are injected for ttyS0 only.
- */
 void serial8250__inject_interrupt(struct kvm *kvm)
 {
-       struct serial8250_device *dev = &devices[0];
+       int i;
 
-       mutex_lock(&dev->mutex);
+       for (i = 0; i < 4; i++) {
+               struct serial8250_device *dev = &devices[i];
 
-       serial8250__receive(kvm, dev);
+               mutex_lock(&dev->mutex);
 
-       if (dev->ier & UART_IER_RDI && dev->lsr & UART_LSR_DR)
-               dev->iir                = UART_IIR_RDI;
-       else if (dev->ier & UART_IER_THRI)
-               dev->iir                = UART_IIR_THRI;
-       else
-               dev->iir                = UART_IIR_NO_INT;
+               serial8250__receive(kvm, dev);
 
-       if (dev->iir != UART_IIR_NO_INT) {
-               kvm__irq_line(kvm, dev->irq, 0);
-               kvm__irq_line(kvm, dev->irq, 1);
-       }
+               if (dev->ier & UART_IER_RDI && dev->lsr & UART_LSR_DR)
+                       dev->iir                = UART_IIR_RDI;
+               else if (dev->ier & UART_IER_THRI)
+                       dev->iir                = UART_IIR_THRI;
+               else
+                       dev->iir                = UART_IIR_NO_INT;
 
-       mutex_unlock(&dev->mutex);
+               if (dev->iir != UART_IIR_NO_INT) {
+                       kvm__irq_line(kvm, dev->irq, 0);
+                       kvm__irq_line(kvm, dev->irq, 1);
+               }
+
+               mutex_unlock(&dev->mutex);
+       }
 }
 
 void serial8250__inject_sysrq(struct kvm *kvm)
@@ -217,7 +223,7 @@ static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, voi
                        char *addr = data;
 
                        if (!(dev->mcr & UART_MCR_LOOP))
-                               term_putc(CONSOLE_8250, addr, size);
+                               term_putc(CONSOLE_8250, addr, size, dev->id);
 
                        dev->iir                = UART_IIR_NO_INT;
                        break;

diff --git a/tools/kvm/include/kvm/term.h b/tools/kvm/include/kvm/term.h
index 4d580e1c5d5ffa21092fb55fbdba8e4457c635bd..37ec731aa1cfa5c8e42a3a81528f7ede9687deac 100644 (file)
--- a/tools/kvm/include/kvm/term.h
+++ b/tools/kvm/include/kvm/term.h
@@ -6,12 +6,13 @@
 #define CONSOLE_8250   1
 #define CONSOLE_VIRTIO 2
 
-int term_putc_iov(int who, struct iovec *iov, int iovcnt);
-int term_getc_iov(int who, struct iovec *iov, int iovcnt);
-int term_putc(int who, char *addr, int cnt);
-int term_getc(int who);
+int term_putc_iov(int who, struct iovec *iov, int iovcnt, int term);
+int term_getc_iov(int who, struct iovec *iov, int iovcnt, int term);
+int term_putc(int who, char *addr, int cnt, int term);
+int term_getc(int who, int term);
 
-bool term_readable(int who);
+bool term_readable(int who, int term);
+void term_set_tty(int term);
 void term_init(void);
 
 #endif /* KVM__TERM_H */

diff --git a/tools/kvm/term.c b/tools/kvm/term.c
index fa4382dde7642b9f14213555b5d37a5cccb8d92c..fb5d71c7fc575344ba7c21a9f5a00ff10033f1b4 100644 (file)
--- a/tools/kvm/term.c
+++ b/tools/kvm/term.c
@@ -5,6 +5,8 @@
 #include <unistd.h>
 #include <sys/uio.h>
 #include <signal.h>
+#include <pty.h>
+#include <utmp.h>
 
 #include "kvm/read-write.h"
 #include "kvm/term.h"
@@ -12,6 +14,10 @@
 #include "kvm/kvm.h"
 #include "kvm/kvm-cpu.h"
 
+
+#define TERM_FD_IN      0
+#define TERM_FD_OUT     1
+
 extern struct kvm *kvm;
 static struct termios  orig_term;
 
@@ -20,14 +26,16 @@ bool term_got_escape        = false;
 
 int active_console;
 
-int term_getc(int who)
+int term_fds[4][2];
+
+int term_getc(int who, int term)
 {
        int c;
 
        if (who != active_console)
                return -1;
 
-       if (read_in_full(STDIN_FILENO, &c, 1) < 0)
+       if (read_in_full(term_fds[term][TERM_FD_IN], &c, 1) < 0)
                return -1;
 
        c &= 0xff;
@@ -48,47 +56,51 @@ int term_getc(int who)
        return c;
 }
 
-int term_putc(int who, char *addr, int cnt)
+int term_putc(int who, char *addr, int cnt, int term)
 {
+       int ret;
+
        if (who != active_console)
                return -1;
 
-       while (cnt--)
-               fprintf(stdout, "%c", *addr++);
+       while (cnt--) {
+               ret = write(term_fds[term][TERM_FD_OUT], addr++, 1);
+               if (ret < 0)
+                       return 0;
+       }
 
-       fflush(stdout);
        return cnt;
 }
 
-int term_getc_iov(int who, struct iovec *iov, int iovcnt)
+int term_getc_iov(int who, struct iovec *iov, int iovcnt, int term)
 {
        int c;
 
        if (who != active_console)
                return 0;
 
-       c = term_getc(who);
+       c = term_getc(who, term);
 
        if (c < 0)
                return 0;
 
-       *((int *)iov[0].iov_base)       = c;
+       *((int *)iov[TERM_FD_IN].iov_base)      = c;
 
        return sizeof(char);
 }
 
-int term_putc_iov(int who, struct iovec *iov, int iovcnt)
+int term_putc_iov(int who, struct iovec *iov, int iovcnt, int term)
 {
        if (who != active_console)
                return 0;
 
-       return writev(STDOUT_FILENO, iov, iovcnt);
+       return writev(term_fds[term][TERM_FD_OUT], iov, iovcnt);
 }
 
-bool term_readable(int who)
+bool term_readable(int who, int term)
 {
        struct pollfd pollfd = (struct pollfd) {
-               .fd     = STDIN_FILENO,
+               .fd     = term_fds[term][TERM_FD_IN],
                .events = POLLIN,
                .revents = 0,
        };
@@ -101,7 +113,10 @@ bool term_readable(int who)
 
 static void term_cleanup(void)
 {
-       tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
+       int i;
+
+       for (i = 0; i < 4; i++)
+               tcsetattr(term_fds[i][TERM_FD_IN], TCSANOW, &orig_term);
 }
 
 static void term_sig_cleanup(int sig)
@@ -111,9 +126,31 @@ static void term_sig_cleanup(int sig)
        raise(sig);
 }
 
+void term_set_tty(int term)
+{
+       struct termios orig_term;
+       int master, slave;
+       char new_pty[PATH_MAX];
+
+       if (tcgetattr(STDIN_FILENO, &orig_term) < 0)
+               die("unable to save initial standard input settings");
+
+       orig_term.c_lflag &= ~(ICANON | ECHO | ISIG);
+
+       if (openpty(&master, &slave, new_pty, &orig_term, NULL) < 0)
+               return;
+
+       close(slave);
+
+       pr_info("Assigned terminal %d to pty %s\n", term, new_pty);
+
+       term_fds[term][TERM_FD_IN] = term_fds[term][TERM_FD_OUT] = master;
+}
+
 void term_init(void)
 {
        struct termios term;
+       int i;
 
        if (tcgetattr(STDIN_FILENO, &orig_term) < 0)
                die("unable to save initial standard input settings");
@@ -122,6 +159,12 @@ void term_init(void)
        term.c_lflag &= ~(ICANON | ECHO | ISIG);
        tcsetattr(STDIN_FILENO, TCSANOW, &term);
 
+       for (i = 0; i < 4; i++)
+               if (term_fds[i][TERM_FD_IN] == 0) {
+                       term_fds[i][TERM_FD_IN] = STDIN_FILENO;
+                       term_fds[i][TERM_FD_OUT] = STDOUT_FILENO;
+               }
+
        signal(SIGTERM, term_sig_cleanup);
        atexit(term_cleanup);
 }

diff --git a/tools/kvm/virtio/console.c b/tools/kvm/virtio/console.c
index c0ccd6c0a5ed97345270577cd201e84bb8044c10..b8801622669b4565eac63a39e7abb6ffc9c6d548 100644 (file)
--- a/tools/kvm/virtio/console.c
+++ b/tools/kvm/virtio/console.c
@@ -67,9 +67,9 @@ static void virtio_console__inject_interrupt_callback(struct kvm *kvm, void *par
 
        vq = param;
 
-       if (term_readable(CONSOLE_VIRTIO) && virt_queue__available(vq)) {
+       if (term_readable(CONSOLE_VIRTIO, 0) && virt_queue__available(vq)) {
                head = virt_queue__get_iov(vq, iov, &out, &in, kvm);
-               len = term_getc_iov(CONSOLE_VIRTIO, iov, in);
+               len = term_getc_iov(CONSOLE_VIRTIO, iov, in, 0);
                virt_queue__set_used_elem(vq, head, len);
                virtio_pci__signal_vq(kvm, &cdev.vpci, vq - cdev.vqs);
        }
@@ -100,7 +100,7 @@ static void virtio_console_handle_callback(struct kvm *kvm, void *param)
 
        while (virt_queue__available(vq)) {
                head = virt_queue__get_iov(vq, iov, &out, &in, kvm);
-               len = term_putc_iov(CONSOLE_VIRTIO, iov, out);
+               len = term_putc_iov(CONSOLE_VIRTIO, iov, out, 0);
                virt_queue__set_used_elem(vq, head, len);
        }