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Commit cf813db0 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/smp: limit number of cpus in possible cpu mask 



Limit the number of bits to the maximum number of cpus a machine
can have.
possible_cpu_mask typically will have more bits set than a machine
may physically have. This results in wasted memory during per-cpu
memory allocations, if the possible mask contains more cpus than
physically possible for a given configuration.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 36a55402

arch/s390/include/asm/sclp.h

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ int sclp_cpu_configure(u8 cpu); 
int sclp_cpu_deconfigure(u8 cpu);

unsigned long long sclp_get_rnmax(void);

unsigned long long sclp_get_rzm(void);

unsigned int sclp_get_max_cpu(void);

int sclp_sdias_blk_count(void);

int sclp_sdias_copy(void *dest, int blk_num, int nr_blks);

int sclp_chp_configure(struct chp_id chpid);

arch/s390/kernel/smp.c

+4 −4
Original line number Diff line number Diff line
@@ -773,11 +773,11 @@ void __noreturn cpu_die(void) 


void __init smp_fill_possible_mask(void)

{

	unsigned int possible, cpu;

	unsigned int possible, sclp, cpu;



	possible = setup_possible_cpus;

	if (!possible)

		possible = MACHINE_IS_VM ? 64 : nr_cpu_ids;

	sclp = sclp_get_max_cpu() ?: nr_cpu_ids;

	possible = setup_possible_cpus ?: nr_cpu_ids;

	possible = min(possible, sclp);

	for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)

		set_cpu_possible(cpu, true);

}

drivers/s390/char/sclp_early.c

+21 −2
Original line number Diff line number Diff line
@@ -20,7 +20,9 @@ struct read_info_sccb { 
	struct	sccb_header header;	/* 0-7 */

	u16	rnmax;			/* 8-9 */

	u8	rnsize;			/* 10 */

	u8	_reserved0[24 - 11];	/* 11-15 */

	u8	_reserved0[16 - 11];	/* 11-15 */

	u16	ncpurl;			/* 16-17 */

	u8	_reserved7[24 - 18];	/* 18-23 */

	u8	loadparm[8];		/* 24-31 */

	u8	_reserved1[48 - 32];	/* 32-47 */

	u64	facilities;		/* 48-55 */
@@ -32,13 +34,16 @@ struct read_info_sccb { 
	u8	_reserved4[100 - 92];	/* 92-99 */

	u32	rnsize2;		/* 100-103 */

	u64	rnmax2;			/* 104-111 */

	u8	_reserved5[4096 - 112];	/* 112-4095 */

	u8	_reserved5[120 - 112];	/* 112-119 */

	u16	hcpua;			/* 120-121 */

	u8	_reserved6[4096 - 122];	/* 122-4095 */

} __packed __aligned(PAGE_SIZE);



static char sccb_early[PAGE_SIZE] __aligned(PAGE_SIZE) __initdata;

static unsigned int sclp_con_has_vt220 __initdata;

static unsigned int sclp_con_has_linemode __initdata;

static unsigned long sclp_hsa_size;

static unsigned int sclp_max_cpu;

static struct sclp_ipl_info sclp_ipl_info;



u64 sclp_facilities;
@@ -102,6 +107,15 @@ static void __init sclp_facilities_detect(struct read_info_sccb *sccb) 
	sclp_rzm = sccb->rnsize ? sccb->rnsize : sccb->rnsize2;

	sclp_rzm <<= 20;



	if (!sccb->hcpua) {

		if (MACHINE_IS_VM)

			sclp_max_cpu = 64;

		else

			sclp_max_cpu = sccb->ncpurl;

	} else {

		sclp_max_cpu = sccb->hcpua + 1;

	}



	/* Save IPL information */

	sclp_ipl_info.is_valid = 1;

	if (sccb->flags & 0x2)
@@ -129,6 +143,11 @@ unsigned long long sclp_get_rzm(void) 
	return sclp_rzm;

}



unsigned int sclp_get_max_cpu(void)

{

	return sclp_max_cpu;

}



/*

 * This function will be called after sclp_facilities_detect(), which gets

 * called from early.c code. The sclp_facilities_detect() function retrieves