From: Marc-André Lureau <marcandre.lureau@redhat.com>
Modify fw_cfg_read_blob() to use DMA if the device supports it.
Return errors, because the operation may fail.
This is a proof-of-concept patch with some FIXME. It uses yield() to
wait for the memory to be cleared. Help on how to improve this is
welcome.
We may also want to switch all the *buf addresses to use only
kmalloc'ed buffer (instead of using stack/image addresses with
dma=false).
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
drivers/firmware/qemu_fw_cfg.c | 132 +++++++++++++++++++++++++++++++++++------
1 file changed, 115 insertions(+), 17 deletions(-)
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 614037703530..a0e24fdf3ae5 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -33,6 +33,7 @@
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/ioport.h>
+#include <linux/dma-mapping.h>
MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
@@ -43,12 +44,25 @@ MODULE_LICENSE("GPL");
#define FW_CFG_ID 0x01
#define FW_CFG_FILE_DIR 0x19
+#define FW_CFG_VERSION_DMA 0x02
+#define FW_CFG_DMA_CTL_ERROR 0x01
+#define FW_CFG_DMA_CTL_READ 0x02
+#define FW_CFG_DMA_CTL_SKIP 0x04
+#define FW_CFG_DMA_CTL_SELECT 0x08
+#define FW_CFG_DMA_CTL_WRITE 0x10
+
/* size in bytes of fw_cfg signature */
#define FW_CFG_SIG_SIZE 4
/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
#define FW_CFG_MAX_FILE_PATH 56
+/* platform device for dma mapping */
+static struct device *dev;
+
+/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
+static u32 fw_cfg_rev;
+
/* fw_cfg file directory entry type */
struct fw_cfg_file {
u32 size;
@@ -57,6 +71,12 @@ struct fw_cfg_file {
char name[FW_CFG_MAX_FILE_PATH];
};
+struct fw_cfg_dma {
+ u32 control;
+ u32 length;
+ u64 address;
+} __packed;
+
/* fw_cfg device i/o register addresses */
static bool fw_cfg_is_mmio;
static phys_addr_t fw_cfg_p_base;
@@ -75,12 +95,73 @@ static inline u16 fw_cfg_sel_endianness(u16 key)
return fw_cfg_is_mmio ? cpu_to_be16(key) : cpu_to_le16(key);
}
+static inline bool fw_cfg_dma_enabled(void)
+{
+ return fw_cfg_rev & FW_CFG_VERSION_DMA && fw_cfg_reg_dma;
+}
+
+static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control)
+{
+ dma_addr_t dma_addr = 0;
+ struct fw_cfg_dma *d;
+ dma_addr_t dma;
+ ssize_t ret = length;
+ enum dma_data_direction dir =
+ (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0);
+
+ if (address && length) {
+ dma_addr = dma_map_single(dev, address, length, dir);
+ if (dma_mapping_error(NULL, dma_addr)) {
+ WARN(1, "%s: failed to map address\n", __func__);
+ return -EFAULT;
+ }
+ }
+
+ d = kmalloc(sizeof(*d), GFP_KERNEL | GFP_DMA);
+ if (!d) {
+ ret = -ENOMEM;
+ goto end;
+ }
+
+ dma = dma_map_single(dev, d, sizeof(*d), DMA_BIDIRECTIONAL);
+ if (dma_mapping_error(NULL, dma)) {
+ WARN(1, "%s: failed to map fw_cfg_dma\n", __func__);
+ ret = -EFAULT;
+ goto end;
+ }
+
+ *d = (struct fw_cfg_dma) {
+ .address = cpu_to_be64(dma_addr),
+ .length = cpu_to_be32(length),
+ .control = cpu_to_be32(control)
+ };
+
+ iowrite32be(dma >> 32, fw_cfg_reg_dma);
+ iowrite32be(dma, fw_cfg_reg_dma + 4);
+ while (be32_to_cpu(d->control) & ~FW_CFG_DMA_CTL_ERROR)
+ yield(); /* FIXME: wait_event? */
+
+ if (be32_to_cpu(d->control) & FW_CFG_DMA_CTL_ERROR)
+ ret = -EIO;
+
+ dma_unmap_single(dev, dma, sizeof(*d), DMA_BIDIRECTIONAL);
+
+end:
+ kfree(d);
+ if (dma_addr)
+ dma_unmap_single(dev, dma_addr, length, dir);
+
+ return ret;
+}
+
/* read chunk of given fw_cfg blob (caller responsible for sanity-check) */
-static inline void fw_cfg_read_blob(u16 key,
- void *buf, loff_t pos, size_t count)
+static ssize_t fw_cfg_read_blob(u16 key,
+ void *buf, loff_t pos, size_t count,
+ bool dma)
{
u32 glk = -1U;
acpi_status status;
+ ssize_t ret = count;
/* If we have ACPI, ensure mutual exclusion against any potential
* device access by the firmware, e.g. via AML methods:
@@ -90,17 +171,36 @@ static inline void fw_cfg_read_blob(u16 key,
/* Should never get here */
WARN(1, "fw_cfg_read_blob: Failed to lock ACPI!\n");
memset(buf, 0, count);
- return;
+ return -EBUSY;
}
mutex_lock(&fw_cfg_dev_lock);
- iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
- while (pos-- > 0)
- ioread8(fw_cfg_reg_data);
- ioread8_rep(fw_cfg_reg_data, buf, count);
+ if (dma && fw_cfg_dma_enabled()) {
+ if (pos == 0) {
+ ret = fw_cfg_dma_transfer(buf, count, key << 16
+ | FW_CFG_DMA_CTL_SELECT
+ | FW_CFG_DMA_CTL_READ);
+ } else {
+ iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
+ ret = fw_cfg_dma_transfer(0, pos, FW_CFG_DMA_CTL_SKIP);
+ if (ret < 0)
+ goto end;
+ ret = fw_cfg_dma_transfer(buf, count,
+ FW_CFG_DMA_CTL_READ);
+ }
+ } else {
+ iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
+ while (pos-- > 0)
+ ioread8(fw_cfg_reg_data);
+ ioread8_rep(fw_cfg_reg_data, buf, count);
+ }
+
+end:
mutex_unlock(&fw_cfg_dev_lock);
acpi_release_global_lock(glk);
+
+ return ret;
}
/* clean up fw_cfg device i/o */
@@ -192,7 +292,7 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
#endif
/* verify fw_cfg device signature */
- fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE);
+ fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE, false);
if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) {
fw_cfg_io_cleanup();
return -ENODEV;
@@ -201,9 +301,6 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev)
return 0;
}
-/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
-static u32 fw_cfg_rev;
-
static ssize_t fw_cfg_showrev(struct kobject *k, struct attribute *a, char *buf)
{
return sprintf(buf, "%u\n", fw_cfg_rev);
@@ -351,8 +448,7 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj,
if (count > entry->f.size - pos)
count = entry->f.size - pos;
- fw_cfg_read_blob(entry->f.select, buf, pos, count);
- return count;
+ return fw_cfg_read_blob(entry->f.select, buf, pos, count, true);
}
static struct bin_attribute fw_cfg_sysfs_attr_raw = {
@@ -505,7 +601,7 @@ static int fw_cfg_register_dir_entries(void)
struct fw_cfg_file *dir;
size_t dir_size;
- fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count));
+ fw_cfg_read_blob(FW_CFG_FILE_DIR, &count, 0, sizeof(count), false);
count = be32_to_cpu(count);
dir_size = count * sizeof(struct fw_cfg_file);
@@ -513,7 +609,7 @@ static int fw_cfg_register_dir_entries(void)
if (!dir)
return -ENOMEM;
- fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size);
+ fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(count), dir_size, true);
for (i = 0; i < count; i++) {
dir[i].size = be32_to_cpu(dir[i].size);
@@ -544,9 +640,10 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
* one fw_cfg device exist system-wide, so if one was already found
* earlier, we might as well stop here.
*/
- if (fw_cfg_sel_ko)
+ if (dev)
return -EBUSY;
+ dev = &pdev->dev;
/* create by_key and by_name subdirs of /sys/firmware/qemu_fw_cfg/ */
err = -ENOMEM;
fw_cfg_sel_ko = kobject_create_and_add("by_key", fw_cfg_top_ko);
@@ -562,7 +659,7 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
goto err_probe;
/* get revision number, add matching top-level attribute */
- fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev));
+ fw_cfg_read_blob(FW_CFG_ID, &fw_cfg_rev, 0, sizeof(fw_cfg_rev), false);
fw_cfg_rev = le32_to_cpu(fw_cfg_rev);
err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr);
if (err)
@@ -587,6 +684,7 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
err_name:
fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
err_sel:
+ dev = NULL;
return err;
}
--
2.14.1.146.gd35faa819
Hi Marc-André,
[auto build test WARNING on linus/master]
[also build test WARNING on v4.14-rc1 next-20170922]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/marcandre-lureau-redhat-com/fw_cfg-add-DMA-operations-etc-vmcoreinfo-support/20170922-182716
config: i386-randconfig-x000-201738 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
# save the attached .config to linux build tree
make ARCH=i386
All warnings (new ones prefixed by >>):
drivers//firmware/qemu_fw_cfg.c: In function 'fw_cfg_dma_transfer':
>> drivers//firmware/qemu_fw_cfg.c:139:18: warning: right shift count >= width of type [-Wshift-count-overflow]
iowrite32be(dma >> 32, fw_cfg_reg_dma);
^~
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from include/uapi/linux/posix_types.h:4,
from include/uapi/linux/types.h:13,
from include/linux/types.h:5,
from include/linux/list.h:4,
from include/linux/module.h:9,
from drivers//firmware/qemu_fw_cfg.c:30:
drivers//firmware/qemu_fw_cfg.c: At top level:
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'strcpy' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:421:2: note: in expansion of macro 'if'
if (p_size == (size_t)-1 && q_size == (size_t)-1)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'kmemdup' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:411:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'kmemdup' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:409:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memchr_inv' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:400:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memchr_inv' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:398:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memchr' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:389:2: note: in expansion of macro 'if'
if (p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memchr' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:387:2: note: in expansion of macro 'if'
if (__builtin_constant_p(size) && p_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:379:2: note: in expansion of macro 'if'
if (p_size < size || q_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:376:3: note: in expansion of macro 'if'
if (q_size < size)
^~
include/linux/compiler.h:162:4: warning: '______f' is static but declared in inline function 'memcmp' which is not static
______f = { \
^
include/linux/compiler.h:154:23: note: in expansion of macro '__trace_if'
#define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) )
^~~~~~~~~~
include/linux/string.h:374:3: note: in expansion of macro 'if'
if (p_size < size)
vim +139 drivers//firmware/qemu_fw_cfg.c
102
103 static ssize_t fw_cfg_dma_transfer(void *address, u32 length, u32 control)
104 {
105 dma_addr_t dma_addr = 0;
106 struct fw_cfg_dma *d;
107 dma_addr_t dma;
108 ssize_t ret = length;
109 enum dma_data_direction dir =
110 (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0);
111
112 if (address && length) {
113 dma_addr = dma_map_single(dev, address, length, dir);
114 if (dma_mapping_error(NULL, dma_addr)) {
115 WARN(1, "%s: failed to map address\n", __func__);
116 return -EFAULT;
117 }
118 }
119
120 d = kmalloc(sizeof(*d), GFP_KERNEL | GFP_DMA);
121 if (!d) {
122 ret = -ENOMEM;
123 goto end;
124 }
125
126 dma = dma_map_single(dev, d, sizeof(*d), DMA_BIDIRECTIONAL);
127 if (dma_mapping_error(NULL, dma)) {
128 WARN(1, "%s: failed to map fw_cfg_dma\n", __func__);
129 ret = -EFAULT;
130 goto end;
131 }
132
133 *d = (struct fw_cfg_dma) {
134 .address = cpu_to_be64(dma_addr),
135 .length = cpu_to_be32(length),
136 .control = cpu_to_be32(control)
137 };
138
> 139 iowrite32be(dma >> 32, fw_cfg_reg_dma);
140 iowrite32be(dma, fw_cfg_reg_dma + 4);
141 while (be32_to_cpu(d->control) & ~FW_CFG_DMA_CTL_ERROR)
142 yield(); /* FIXME: wait_event? */
143
144 if (be32_to_cpu(d->control) & FW_CFG_DMA_CTL_ERROR)
145 ret = -EIO;
146
147 dma_unmap_single(dev, dma, sizeof(*d), DMA_BIDIRECTIONAL);
148
149 end:
150 kfree(d);
151 if (dma_addr)
152 dma_unmap_single(dev, dma_addr, length, dir);
153
154 return ret;
155 }
156
---
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