xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

s390/vmcp: make use of contiguous memory allocator

Browse Source 
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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens
2017-08-07 15:16:15 +02:00
committed by Martin Schwidefsky
parent cd4386a931
commit 3f4298427a
6 changed files with 90 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

74
drivers/s390/char/vmcp.c
View File

@@ -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;