Re: [kvm-unit-tests PATCH v2 1/4] lib: s390x: add support for SCLP console read

Thomas Huth
2022-04-13T15:43:05Z

On 13/04/2022 17.26, Nico Boehr wrote:
> Add a basic implementation for reading from the SCLP ASCII console. The goal of
> this is to support migration tests on s390x. To know when the migration has been
> finished, we need to listen for a newline on our console.
>
> Hence, this implementation is focused on the SCLP ASCII console of QEMU and
> currently won't work under e.g. LPAR.
>
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
> lib/s390x/sclp-console.c | 79 +++++++++++++++++++++++++++++++++++++---
> lib/s390x/sclp.h | 8 ++++
> s390x/Makefile | 1 +
> 3 files changed, 82 insertions(+), 6 deletions(-)
>
> diff --git a/lib/s390x/sclp-console.c b/lib/s390x/sclp-console.c
> index fa36a6a42381..e580de6830d6 100644
> --- a/lib/s390x/sclp-console.c
> +++ b/lib/s390x/sclp-console.c
> @@ -89,6 +89,10 @@ static char lm_buff[120];
> static unsigned char lm_buff_off;
> static struct spinlock lm_buff_lock;
>
> +static char read_buf[4096];
> +static int read_index = sizeof(read_buf) - 1;
> +static int read_buf_end = 0;
> +
> static void sclp_print_ascii(const char *str)
> {
> int len = strlen(str);
> @@ -185,7 +189,7 @@ static void sclp_print_lm(const char *str)
> * indicating which messages the control program (we) want(s) to
> * send/receive.
> */
> -static void sclp_set_write_mask(void)
> +static void sclp_write_event_mask(int receive_mask, int send_mask)
> {
> WriteEventMask *sccb = (void *)_sccb;
>
> @@ -195,18 +199,27 @@ static void sclp_set_write_mask(void)
> sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
> sccb->mask_length = sizeof(sccb_mask_t);
>
> - /* For now we don't process sclp input. */
> - sccb->cp_receive_mask = 0;
> - /* We send ASCII and line mode. */
> - sccb->cp_send_mask = SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG;
> + sccb->cp_receive_mask = receive_mask;
> + sccb->cp_send_mask = send_mask;
>
> sclp_service_call(SCLP_CMD_WRITE_EVENT_MASK, sccb);
> assert(sccb->h.response_code == SCLP_RC_NORMAL_COMPLETION);
> }
>
> +static void sclp_console_enable_read(void)
> +{
> + sclp_write_event_mask(SCLP_EVENT_MASK_MSG_ASCII, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
> +}
> +
> +static void sclp_console_disable_read(void)
> +{
> + sclp_write_event_mask(0, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
> +}
> +
> void sclp_console_setup(void)
> {
> - sclp_set_write_mask();
> + /* We send ASCII and line mode. */
> + sclp_write_event_mask(0, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
> }
>
> void sclp_print(const char *str)
> @@ -227,3 +240,57 @@ void sclp_print(const char *str)
> sclp_print_ascii(str);
> sclp_print_lm(str);
> }
> +
> +static int console_refill_read_buffer(void)
> +{
> + const int max_event_buffer_len = SCCB_SIZE - offsetof(ReadEventDataAsciiConsole, ebh);
> + ReadEventDataAsciiConsole *sccb = (void *)_sccb;
> + const int event_buffer_ascii_recv_header_len = sizeof(sccb->ebh) + sizeof(sccb->type);
> + int ret = -1;
> +
> + sclp_console_enable_read();
> +
> + sclp_mark_busy();
> + memset(sccb, 0, SCCB_SIZE);
> + sccb->h.length = PAGE_SIZE;
> + sccb->h.function_code = SCLP_UNCONDITIONAL_READ;
> + sccb->h.control_mask[2] = SCLP_CM2_VARIABLE_LENGTH_RESPONSE;
> +
> + sclp_service_call(SCLP_CMD_READ_EVENT_DATA, sccb);
> +
> + if ((sccb->h.response_code == SCLP_RC_NO_EVENT_BUFFERS_STORED) ||
> + (sccb->ebh.type != SCLP_EVENT_ASCII_CONSOLE_DATA) ||
> + (sccb->type != SCLP_EVENT_ASCII_TYPE_DATA_STREAM_FOLLOWS)) {

Cosmetic nit: You could drop the innermost braces.

> + ret = -1;
> + goto out;
> + }
> +
> + assert(sccb->ebh.length <= max_event_buffer_len);
> + assert(sccb->ebh.length > event_buffer_ascii_recv_header_len);
> +
> + read_buf_end = sccb->ebh.length - event_buffer_ascii_recv_header_len;
> +
> + assert(read_buf_end <= sizeof(read_buf));
> + memcpy(read_buf, sccb->data, read_buf_end);
> +
> + read_index = 0;
> + ret = 0;
> +
> +out:
> + sclp_console_disable_read();
> +
> + return ret;
> +}
> +
> +int __getchar(void)
> +{
> + int ret;
> +
> + if (read_index >= read_buf_end) {
> + ret = console_refill_read_buffer();
> + if (ret < 0)
> + return ret;
> + }
> +
> + return read_buf[read_index++];
> +}
> diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
> index fead007a6037..e48a5a3df20b 100644
> --- a/lib/s390x/sclp.h
> +++ b/lib/s390x/sclp.h
> @@ -313,6 +313,14 @@ typedef struct ReadEventData {
> uint32_t mask;
> } __attribute__((packed)) ReadEventData;
>
> +#define SCLP_EVENT_ASCII_TYPE_DATA_STREAM_FOLLOWS 0
> +typedef struct ReadEventDataAsciiConsole {
> + SCCBHeader h;
> + EventBufferHeader ebh;
> + uint8_t type;
> + char data[];
> +} __attribute__((packed)) ReadEventDataAsciiConsole;
> +
> extern char _sccb[];
> void sclp_setup_int(void);
> void sclp_handle_ext(void);
> diff --git a/s390x/Makefile b/s390x/Makefile
> index c11f6efbd767..f38f442b9cb1 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -75,6 +75,7 @@ cflatobjs += lib/alloc_phys.o
> cflatobjs += lib/alloc_page.o
> cflatobjs += lib/vmalloc.o
> cflatobjs += lib/alloc_phys.o
> +cflatobjs += lib/getchar.o
> cflatobjs += lib/s390x/io.o
> cflatobjs += lib/s390x/stack.o
> cflatobjs += lib/s390x/sclp.o

Reviewed-by: Thomas Huth <thuth@redhat.com>