Commit 3f429842 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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s390/vmcp: make use of contiguous memory allocator



If memory is fragmented it is unlikely that large order memory
allocations succeed. This has been an issue with the vmcp device
driver since a long time, since it requires large physical contiguous
memory ares for large responses.

To hopefully resolve this issue make use of the contiguous memory
allocator (cma). This patch adds a vmcp specific vmcp cma area with a
default size of 4MB. The size can be changed either via the
VMCP_CMA_SIZE config option at compile time or with the "vmcp_cma"
kernel parameter (e.g. "vmcp_cma=16m").

For any vmcp response buffers larger than 16k memory from the cma area
will be allocated. If such an allocation fails, there is a fallback to
the buddy allocator.
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent cd4386a9
......@@ -4375,6 +4375,10 @@
decrease the size and leave more room for directly
mapped kernel RAM.
vmcp_cma=nn[MG] [KNL,S390]
Sets the memory size reserved for contiguous memory
allocations for the vmcp device driver.
vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
Format: <command>
......
......@@ -108,6 +108,12 @@ extern void pfault_fini(void);
#define pfault_fini() do { } while (0)
#endif /* CONFIG_PFAULT */
#ifdef CONFIG_VMCP
void vmcp_cma_reserve(void);
#else
static inline void vmcp_cma_reserve(void) { }
#endif
void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault);
void cmma_init(void);
......
......@@ -925,6 +925,7 @@ void __init setup_arch(char **cmdline_p)
setup_memory_end();
setup_memory();
dma_contiguous_reserve(memory_end);
vmcp_cma_reserve();
check_initrd();
reserve_crashkernel();
......
......@@ -169,10 +169,21 @@ config VMCP
def_bool y
prompt "Support for the z/VM CP interface"
depends on S390
select CMA
help
Select this option if you want to be able to interact with the control
program on z/VM
config VMCP_CMA_SIZE
int "Memory in MiB reserved for z/VM CP interface"
default "4"
depends on VMCP
help
Specify the default amount of memory in MiB reserved for the z/VM CP
interface. If needed this memory is used for large contiguous memory
allocations. The default can be changed with the kernel command line
parameter "vmcp_cma".
config MONREADER
def_tristate m
prompt "API for reading z/VM monitor service records"
......
......@@ -17,15 +17,77 @@
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/cma.h>
#include <linux/mm.h>
#include <asm/compat.h>
#include <asm/cpcmd.h>
#include <asm/debug.h>
#include <linux/uaccess.h>
#include "vmcp.h"
static debug_info_t *vmcp_debug;
static unsigned long vmcp_cma_size __initdata = CONFIG_VMCP_CMA_SIZE * 1024 * 1024;
static struct cma *vmcp_cma;
static int __init early_parse_vmcp_cma(char *p)
{
vmcp_cma_size = ALIGN(memparse(p, NULL), PAGE_SIZE);
return 0;
}
early_param("vmcp_cma", early_parse_vmcp_cma);
void __init vmcp_cma_reserve(void)
{
if (!MACHINE_IS_VM)
return;
cma_declare_contiguous(0, vmcp_cma_size, 0, 0, 0, false, "vmcp", &vmcp_cma);
}
static void vmcp_response_alloc(struct vmcp_session *session)
{
struct page *page = NULL;
int nr_pages, order;
order = get_order(session->bufsize);
nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
/*
* For anything below order 3 allocations rely on the buddy
* allocator. If such low-order allocations can't be handled
* anymore the system won't work anyway.
*/
if (order > 2)
page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL);
if (page) {
session->response = (char *)page_to_phys(page);
session->cma_alloc = 1;
return;
}
session->response = (char *)__get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, order);
}
static void vmcp_response_free(struct vmcp_session *session)
{
int nr_pages, order;
struct page *page;
if (!session->response)
return;
order = get_order(session->bufsize);
nr_pages = ALIGN(session->bufsize, PAGE_SIZE) >> PAGE_SHIFT;
if (session->cma_alloc) {
page = phys_to_page((unsigned long)session->response);
cma_release(vmcp_cma, page, nr_pages);
session->cma_alloc = 0;
goto out;
}
free_pages((unsigned long)session->response, order);
out:
session->response = NULL;
}
static int vmcp_open(struct inode *inode, struct file *file)
{
struct vmcp_session *session;
......@@ -51,7 +113,7 @@ static int vmcp_release(struct inode *inode, struct file *file)
session = file->private_data;
file->private_data = NULL;
free_pages((unsigned long)session->response, get_order(session->bufsize));
vmcp_response_free(session);
kfree(session);
return 0;
}
......@@ -97,9 +159,7 @@ vmcp_write(struct file *file, const char __user *buff, size_t count,
return -ERESTARTSYS;
}
if (!session->response)
session->response = (char *)__get_free_pages(GFP_KERNEL
| __GFP_RETRY_MAYFAIL,
get_order(session->bufsize));
vmcp_response_alloc(session);
if (!session->response) {
mutex_unlock(&session->mutex);
kfree(cmd);
......@@ -146,9 +206,7 @@ static long vmcp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
mutex_unlock(&session->mutex);
return put_user(temp, argp);
case VMCP_SETBUF:
free_pages((unsigned long)session->response,
get_order(session->bufsize));
session->response=NULL;
vmcp_response_free(session);
temp = get_user(session->bufsize, argp);
if (temp)
session->bufsize = PAGE_SIZE;
......
......@@ -20,8 +20,9 @@
#define VMCP_GETSIZE _IOR(0x10, 3, int)
struct vmcp_session {
unsigned int bufsize;
char *response;
unsigned int bufsize;
unsigned int cma_alloc : 1;
int resp_size;
int resp_code;
/* As we use copy_from/to_user, which might *
......
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