diff mbox series

[kvm-unit-tests,v3,07/13] s390x: Use interrupts in SCLP

Message ID 20181218092657.46466-8-frankja@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series 390x: Add cross hypervisor and disk boot | expand

Commit Message

Janosch Frank Dec. 18, 2018, 9:26 a.m. UTC 
We need to properly implement interrupt handling for SCLP, because on
z/VM and LPAR SCLP calls are not synchronous!

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
 lib/s390x/asm/arch_def.h  |  1 +
 lib/s390x/asm/interrupt.h |  2 ++
 lib/s390x/interrupt.c     | 12 ++++++++++--
 lib/s390x/io.c            |  2 +-
 lib/s390x/sclp-console.c  |  3 +++
 lib/s390x/sclp.c          | 39 +++++++++++++++++++++++++++++++++++++--
 lib/s390x/sclp.h          |  4 ++++
 7 files changed, 58 insertions(+), 5 deletions(-)

Comments

Thomas Huth Dec. 18, 2018, 10:49 a.m. UTC | #1 
On 2018-12-18 10:26, Janosch Frank wrote:
> We need to properly implement interrupt handling for SCLP, because on
> z/VM and LPAR SCLP calls are not synchronous!
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  lib/s390x/asm/arch_def.h  |  1 +
>  lib/s390x/asm/interrupt.h |  2 ++
>  lib/s390x/interrupt.c     | 12 ++++++++++--
>  lib/s390x/io.c            |  2 +-
>  lib/s390x/sclp-console.c  |  3 +++
>  lib/s390x/sclp.c          | 39 +++++++++++++++++++++++++++++++++++++--
>  lib/s390x/sclp.h          |  4 ++++
>  7 files changed, 58 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
> index d2d6e02..27c6b85 100644
> --- a/lib/s390x/asm/arch_def.h
> +++ b/lib/s390x/asm/arch_def.h
> @@ -33,6 +33,7 @@ struct psw {
>  	uint64_t	addr;
>  };
>  
> +#define PSW_MASK_EXT			0x0100000000000000UL
>  #define PSW_MASK_DAT			0x0400000000000000UL
>  #define PSW_MASK_PSTATE			0x0001000000000000UL
>  
> diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
> index 013709f..f485e96 100644
> --- a/lib/s390x/asm/interrupt.h
> +++ b/lib/s390x/asm/interrupt.h
> @@ -11,6 +11,8 @@
>  #define _ASMS390X_IRQ_H_
>  #include <asm/arch_def.h>
>  
> +#define EXT_IRQ_SERVICE_SIG	0x2401
> +
>  void handle_pgm_int(void);
>  void handle_ext_int(void);
>  void handle_mcck_int(void);
> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
> index cf0a794..7118577 100644
> --- a/lib/s390x/interrupt.c
> +++ b/lib/s390x/interrupt.c
> @@ -12,6 +12,7 @@
>  #include <libcflat.h>
>  #include <asm/interrupt.h>
>  #include <asm/barrier.h>
> +#include <sclp.h>
>  
>  static bool pgm_int_expected;
>  static struct lowcore *lc;
> @@ -107,8 +108,15 @@ void handle_pgm_int(void)
>  
>  void handle_ext_int(void)
>  {
> -	report_abort("Unexpected external call interrupt: at %#lx",
> -		     lc->ext_old_psw.addr);
> +	if (lc->ext_int_code != EXT_IRQ_SERVICE_SIG)
> +		report_abort("Unexpected external call interrupt: at %#lx",
> +			     lc->ext_old_psw.addr);

Since we're (mostly) using kernel coding style, could you please add
curly braces around that report_abort() statement, too?

> +	else {
> +		lc->ext_old_psw.mask &= ~PSW_MASK_EXT;
> +		lc->sw_int_cr0 &= ~(1UL << 9);
> +		sclp_handle_ext();
> +		lc->ext_int_code = 0;
> +	}
>  }
>  
>  void handle_mcck_int(void)
> diff --git a/lib/s390x/io.c b/lib/s390x/io.c
> index 05a0765..7294165 100644
> --- a/lib/s390x/io.c
> +++ b/lib/s390x/io.c
> @@ -45,8 +45,8 @@ void setup(void)
>  {
>  	setup_args_progname(ipl_args);
>  	setup_facilities();
> -	sclp_console_setup();
>  	sclp_memory_setup();
> +	sclp_console_setup();

Why this change?

>  }
>  
>  void exit(int code)
> diff --git a/lib/s390x/sclp-console.c b/lib/s390x/sclp-console.c
> index bc01f41..2016ea0 100644
> --- a/lib/s390x/sclp-console.c
> +++ b/lib/s390x/sclp-console.c
> @@ -17,6 +17,7 @@ static void sclp_set_write_mask(void)
>  {
>  	WriteEventMask *sccb = (void *)_sccb;
>  
> +	sclp_mark_busy();
>  	sccb->h.length = sizeof(WriteEventMask);
>  	sccb->mask_length = sizeof(unsigned int);
>  	sccb->receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
> @@ -37,6 +38,7 @@ void sclp_print(const char *str)
>  	int len = strlen(str);
>  	WriteEventData *sccb = (void *)_sccb;
>  
> +	sclp_mark_busy();
>  	sccb->h.length = sizeof(WriteEventData) + len;
>  	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
>  	sccb->ebh.length = sizeof(EventBufferHeader) + len;
> @@ -45,4 +47,5 @@ void sclp_print(const char *str)
>  	memcpy(sccb->data, str, len);
>  
>  	sclp_service_call(SCLP_CMD_WRITE_EVENT_DATA, sccb);
> +	sclp_wait_busy();
>  }

I wonder whether it would be easier / less error prone if we'd do the
sclp_mark_busy() at the start of sclp_service_call() and then simply
always sclp_wait_busy() at the end of sclp_service_call() ?

> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 7f556e5..eed51ef 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -14,6 +14,7 @@
>  #include <asm/page.h>
>  #include <asm/arch_def.h>
>  #include <asm/interrupt.h>
> +#include <asm/barrier.h>
>  #include "sclp.h"
>  #include <alloc_phys.h>
>  
> @@ -24,6 +25,7 @@ static uint64_t max_ram_size;
>  static uint64_t ram_size;
>  
>  char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
> +volatile bool sclp_busy;
>  
>  static void mem_init(phys_addr_t mem_end)
>  {
> @@ -32,17 +34,49 @@ static void mem_init(phys_addr_t mem_end)
>  	phys_alloc_init(freemem_start, mem_end - freemem_start);
>  }
>  
> +static void sclp_setup_int(void)
> +{
> +	uint64_t mask;
> +
> +	ctl_set_bit(0, 9);
> +
> +	mask = extract_psw_mask();
> +	mask |= PSW_MASK_EXT;
> +	load_psw_mask(mask);
> +}
> +
> +void sclp_handle_ext(void)
> +{
> +	ctl_clear_bit(0, 9);
> +	sclp_busy = false;
> +}
> +
> +void sclp_wait_busy(void)
> +{
> +	mb();
> +	while (sclp_busy)
> +		/* Wait for SCLP request to complete */;
> +}

I'd maybe rather write this as:

	while (sclp_busy)
		mb();

... but it should not really matter.

 Thomas
Thomas Huth Dec. 18, 2018, 11:42 a.m. UTC | #2 
On 2018-12-18 10:26, Janosch Frank wrote:
> We need to properly implement interrupt handling for SCLP, because on
> z/VM and LPAR SCLP calls are not synchronous!
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  lib/s390x/asm/arch_def.h  |  1 +
>  lib/s390x/asm/interrupt.h |  2 ++
>  lib/s390x/interrupt.c     | 12 ++++++++++--
>  lib/s390x/io.c            |  2 +-
>  lib/s390x/sclp-console.c  |  3 +++
>  lib/s390x/sclp.c          | 39 +++++++++++++++++++++++++++++++++++++--
>  lib/s390x/sclp.h          |  4 ++++
>  7 files changed, 58 insertions(+), 5 deletions(-)
[...]
> diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
> index 7f556e5..eed51ef 100644
> --- a/lib/s390x/sclp.c
> +++ b/lib/s390x/sclp.c
> @@ -14,6 +14,7 @@
>  #include <asm/page.h>
>  #include <asm/arch_def.h>
>  #include <asm/interrupt.h>
> +#include <asm/barrier.h>
>  #include "sclp.h"
>  #include <alloc_phys.h>
>  
> @@ -24,6 +25,7 @@ static uint64_t max_ram_size;
>  static uint64_t ram_size;
>  
>  char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
> +volatile bool sclp_busy;

I think this should rather be static (since you provide a
"sclp_mark_busy" function to access it from other files

 Thomas
Janosch Frank Dec. 18, 2018, 11:57 a.m. UTC | #3 
On 18.12.18 11:49, Thomas Huth wrote:
> On 2018-12-18 10:26, Janosch Frank wrote:
>> We need to properly implement interrupt handling for SCLP, because on
>> z/VM and LPAR SCLP calls are not synchronous!
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---

[...]

> 
> I'd maybe rather write this as:
> 
> 	while (sclp_busy)
> 		mb();
> 
> ... but it should not really matter.
> 
>  Thomas
> 

All suggestions sound reasonable :)
diff mbox series

Patch

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index d2d6e02..27c6b85 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -33,6 +33,7 @@  struct psw {
 	uint64_t	addr;
 };
 
+#define PSW_MASK_EXT			0x0100000000000000UL
 #define PSW_MASK_DAT			0x0400000000000000UL
 #define PSW_MASK_PSTATE			0x0001000000000000UL
 
diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
index 013709f..f485e96 100644
--- a/lib/s390x/asm/interrupt.h
+++ b/lib/s390x/asm/interrupt.h
@@ -11,6 +11,8 @@ 
 #define _ASMS390X_IRQ_H_
 #include <asm/arch_def.h>
 
+#define EXT_IRQ_SERVICE_SIG	0x2401
+
 void handle_pgm_int(void);
 void handle_ext_int(void);
 void handle_mcck_int(void);
diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
index cf0a794..7118577 100644
--- a/lib/s390x/interrupt.c
+++ b/lib/s390x/interrupt.c
@@ -12,6 +12,7 @@ 
 #include <libcflat.h>
 #include <asm/interrupt.h>
 #include <asm/barrier.h>
+#include <sclp.h>
 
 static bool pgm_int_expected;
 static struct lowcore *lc;
@@ -107,8 +108,15 @@  void handle_pgm_int(void)
 
 void handle_ext_int(void)
 {
-	report_abort("Unexpected external call interrupt: at %#lx",
-		     lc->ext_old_psw.addr);
+	if (lc->ext_int_code != EXT_IRQ_SERVICE_SIG)
+		report_abort("Unexpected external call interrupt: at %#lx",
+			     lc->ext_old_psw.addr);
+	else {
+		lc->ext_old_psw.mask &= ~PSW_MASK_EXT;
+		lc->sw_int_cr0 &= ~(1UL << 9);
+		sclp_handle_ext();
+		lc->ext_int_code = 0;
+	}
 }
 
 void handle_mcck_int(void)
diff --git a/lib/s390x/io.c b/lib/s390x/io.c
index 05a0765..7294165 100644
--- a/lib/s390x/io.c
+++ b/lib/s390x/io.c
@@ -45,8 +45,8 @@  void setup(void)
 {
 	setup_args_progname(ipl_args);
 	setup_facilities();
-	sclp_console_setup();
 	sclp_memory_setup();
+	sclp_console_setup();
 }
 
 void exit(int code)
diff --git a/lib/s390x/sclp-console.c b/lib/s390x/sclp-console.c
index bc01f41..2016ea0 100644
--- a/lib/s390x/sclp-console.c
+++ b/lib/s390x/sclp-console.c
@@ -17,6 +17,7 @@  static void sclp_set_write_mask(void)
 {
 	WriteEventMask *sccb = (void *)_sccb;
 
+	sclp_mark_busy();
 	sccb->h.length = sizeof(WriteEventMask);
 	sccb->mask_length = sizeof(unsigned int);
 	sccb->receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
@@ -37,6 +38,7 @@  void sclp_print(const char *str)
 	int len = strlen(str);
 	WriteEventData *sccb = (void *)_sccb;
 
+	sclp_mark_busy();
 	sccb->h.length = sizeof(WriteEventData) + len;
 	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
 	sccb->ebh.length = sizeof(EventBufferHeader) + len;
@@ -45,4 +47,5 @@  void sclp_print(const char *str)
 	memcpy(sccb->data, str, len);
 
 	sclp_service_call(SCLP_CMD_WRITE_EVENT_DATA, sccb);
+	sclp_wait_busy();
 }
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 7f556e5..eed51ef 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -14,6 +14,7 @@ 
 #include <asm/page.h>
 #include <asm/arch_def.h>
 #include <asm/interrupt.h>
+#include <asm/barrier.h>
 #include "sclp.h"
 #include <alloc_phys.h>
 
@@ -24,6 +25,7 @@  static uint64_t max_ram_size;
 static uint64_t ram_size;
 
 char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
+volatile bool sclp_busy;
 
 static void mem_init(phys_addr_t mem_end)
 {
@@ -32,17 +34,49 @@  static void mem_init(phys_addr_t mem_end)
 	phys_alloc_init(freemem_start, mem_end - freemem_start);
 }
 
+static void sclp_setup_int(void)
+{
+	uint64_t mask;
+
+	ctl_set_bit(0, 9);
+
+	mask = extract_psw_mask();
+	mask |= PSW_MASK_EXT;
+	load_psw_mask(mask);
+}
+
+void sclp_handle_ext(void)
+{
+	ctl_clear_bit(0, 9);
+	sclp_busy = false;
+}
+
+void sclp_wait_busy(void)
+{
+	mb();
+	while (sclp_busy)
+		/* Wait for SCLP request to complete */;
+}
+
+void sclp_mark_busy(void)
+{
+	sclp_busy = true;
+}
+
 static void sclp_read_scp_info(ReadInfo *ri, int length)
 {
 	unsigned int commands[] = { SCLP_CMDW_READ_SCP_INFO_FORCED,
 				    SCLP_CMDW_READ_SCP_INFO };
-	int i;
+	int i, cc;
 
 	for (i = 0; i < ARRAY_SIZE(commands); i++) {
 		memset(&ri->h, 0, sizeof(ri->h));
 		ri->h.length = length;
 
-		if (sclp_service_call(commands[i], ri))
+		sclp_mark_busy();
+		cc = sclp_service_call(commands[i], ri);
+		sclp_wait_busy();
+		if (cc)
 			break;
 		if (ri->h.response_code == SCLP_RC_NORMAL_READ_COMPLETION)
 			return;
@@ -57,6 +91,7 @@  int sclp_service_call(unsigned int command, void *sccb)
 {
 	int cc;
 
+	sclp_setup_int();
 	asm volatile(
 		"       .insn   rre,0xb2200000,%1,%2\n"  /* servc %1,%2 */
 		"       ipm     %0\n"
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index 583c4e5..427b0d7 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -213,6 +213,10 @@  typedef struct ReadEventData {
 } __attribute__((packed)) ReadEventData;
 
 extern char _sccb[];
+volatile bool sclp_busy;
+void sclp_handle_ext(void);
+void sclp_wait_busy(void);
+void sclp_mark_busy(void);
 void sclp_console_setup(void);
 void sclp_print(const char *str);
 int sclp_service_call(unsigned int command, void *sccb);