This patch makes SIGQUIT to the host hypervisor send 'SysRq-P' to the guest kernel via 8250 serial console to make debugging stuck guests easier.
Cc: Asias He <[email protected]> Cc: Cyrill Gorcunov <[email protected]> Cc: Ingo Molnar <[email protected]> Signed-off-by: Pekka Enberg <[email protected]> --- tools/kvm/8250-serial.c | 33 +++++++++++++++++++++++++++++++++ tools/kvm/include/kvm/8250-serial.h | 1 + tools/kvm/main.c | 1 + 3 files changed, 35 insertions(+), 0 deletions(-) diff --git a/tools/kvm/8250-serial.c b/tools/kvm/8250-serial.c index e92ff89..639afb2 100644 --- a/tools/kvm/8250-serial.c +++ b/tools/kvm/8250-serial.c @@ -53,6 +53,29 @@ static struct serial8250_device devices[] = { }, }; +#define SYSRQ_PENDING_NONE 0 +#define SYSRQ_PENDING_BREAK 1 +#define SYSRQ_PENDING_CMD 2 + +static int sysrq_pending; + +static void serial8250__sysrq(struct kvm *self, struct serial8250_device *dev) +{ + switch (sysrq_pending) { + case SYSRQ_PENDING_BREAK: + dev->lsr |= UART_LSR_DR | UART_LSR_BI; + + sysrq_pending = SYSRQ_PENDING_CMD; + break; + case SYSRQ_PENDING_CMD: + dev->rbr = 'p'; + dev->lsr |= UART_LSR_DR; + + sysrq_pending = SYSRQ_PENDING_NONE; + break; + } +} + static void serial8250__receive(struct kvm *self, struct serial8250_device *dev) { int c; @@ -60,6 +83,11 @@ static void serial8250__receive(struct kvm *self, struct serial8250_device *dev) if (dev->lsr & UART_LSR_DR) return; + if (sysrq_pending) { + serial8250__sysrq(self, dev); + return; + } + if (!term_readable(CONSOLE_8250)) return; @@ -94,6 +122,11 @@ void serial8250__inject_interrupt(struct kvm *self) } } +void serial8250__inject_sysrq(struct kvm *self) +{ + sysrq_pending = SYSRQ_PENDING_BREAK; +} + static struct serial8250_device *find_device(uint16_t port) { unsigned int i; diff --git a/tools/kvm/include/kvm/8250-serial.h b/tools/kvm/include/kvm/8250-serial.h index 73ed078..7a6d3f3 100644 --- a/tools/kvm/include/kvm/8250-serial.h +++ b/tools/kvm/include/kvm/8250-serial.h @@ -5,5 +5,6 @@ struct kvm; void serial8250__init(struct kvm *kvm); void serial8250__inject_interrupt(struct kvm *kvm); +void serial8250__inject_sysrq(struct kvm *kvm); #endif /* KVM__8250_SERIAL_H */ diff --git a/tools/kvm/main.c b/tools/kvm/main.c index 6aa2534..d8f0c09 100644 --- a/tools/kvm/main.c +++ b/tools/kvm/main.c @@ -38,6 +38,7 @@ static void handle_sigint(int sig) static void handle_sigquit(int sig) { + serial8250__inject_sysrq(kvm); kvm__show_registers(kvm); kvm__show_code(kvm); kvm__show_page_tables(kvm); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
