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Subject[PATCH v12 4/4] fw_cfg: write vmcoreinfo details
Date
If the "etc/vmcoreinfo" fw_cfg file is present and we are not running
the kdump kernel, write the addr/size of the vmcoreinfo ELF note.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Gabriel Somlo <somlo@cmu.edu>
---
drivers/firmware/qemu_fw_cfg.c | 84 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 84 insertions(+)

diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 19ee776a1e92..08309939cd94 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -34,6 +34,8 @@
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/delay.h>
+#include <linux/crash_dump.h>
+#include <linux/crash_core.h>

MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>");
MODULE_DESCRIPTION("QEMU fw_cfg sysfs support");
@@ -57,6 +59,8 @@ MODULE_LICENSE("GPL");
/* fw_cfg "file name" is up to 56 characters (including terminating nul) */
#define FW_CFG_MAX_FILE_PATH 56

+#define VMCOREINFO_FORMAT_ELF 0x1
+
/* fw_cfg revision attribute, in /sys/firmware/qemu_fw_cfg top-level dir. */
static u32 fw_cfg_rev;

@@ -195,6 +199,47 @@ static ssize_t fw_cfg_read_blob(struct device *dev, u16 key,
return ret;
}

+#ifdef CONFIG_CRASH_CORE
+/* write chunk of given fw_cfg blob (caller responsible for sanity-check) */
+static ssize_t fw_cfg_write_blob(struct device *dev, u16 key,
+ void *buf, loff_t pos, size_t count)
+{
+ 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:
+ */
+ status = acpi_acquire_global_lock(ACPI_WAIT_FOREVER, &glk);
+ if (ACPI_FAILURE(status) && status != AE_NOT_CONFIGURED) {
+ /* Should never get here */
+ WARN(1, "%s: Failed to lock ACPI!\n", __func__);
+ return -EINVAL;
+ }
+
+ mutex_lock(&fw_cfg_dev_lock);
+ if (pos == 0) {
+ ret = fw_cfg_dma_transfer(dev, buf, count, key << 16
+ | FW_CFG_DMA_CTL_SELECT
+ | FW_CFG_DMA_CTL_WRITE);
+ } else {
+ iowrite16(fw_cfg_sel_endianness(key), fw_cfg_reg_ctrl);
+ ret = fw_cfg_dma_transfer(dev, NULL, pos, FW_CFG_DMA_CTL_SKIP);
+ if (ret < 0)
+ goto end;
+ ret = fw_cfg_dma_transfer(dev, buf, count, FW_CFG_DMA_CTL_WRITE);
+ }
+
+end:
+ mutex_unlock(&fw_cfg_dev_lock);
+
+ acpi_release_global_lock(glk);
+
+ return ret;
+}
+#endif /* CONFIG_CRASH_CORE */
+
/* clean up fw_cfg device i/o */
static void fw_cfg_io_cleanup(void)
{
@@ -314,6 +359,37 @@ struct fw_cfg_sysfs_entry {
struct device *dev;
};

+#ifdef CONFIG_CRASH_CORE
+static ssize_t write_vmcoreinfo(struct device *dev, const struct fw_cfg_file *f)
+{
+ struct vmci {
+ __le16 host_format;
+ __le16 guest_format;
+ __le32 size;
+ __le64 paddr;
+ } __packed;
+ static struct vmci *data;
+ ssize_t ret;
+
+ data = kmalloc(sizeof(struct vmci), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ *data = (struct vmci) {
+ .guest_format = cpu_to_le16(VMCOREINFO_FORMAT_ELF),
+ .size = cpu_to_le32(VMCOREINFO_NOTE_SIZE),
+ .paddr = cpu_to_le64(paddr_vmcoreinfo_note())
+ };
+ /* spare ourself reading host format support for now since we
+ * don't know what else to format - host may ignore ours
+ */
+ ret = fw_cfg_write_blob(dev, f->select, data, 0, sizeof(struct vmci));
+
+ kfree(data);
+ return ret;
+}
+#endif /* CONFIG_CRASH_CORE */
+
/* get fw_cfg_sysfs_entry from kobject member */
static inline struct fw_cfg_sysfs_entry *to_entry(struct kobject *kobj)
{
@@ -555,6 +631,14 @@ static int fw_cfg_register_file(struct device *dev, const struct fw_cfg_file *f)
int err;
struct fw_cfg_sysfs_entry *entry;

+#ifdef CONFIG_CRASH_CORE
+ if (fw_cfg_dma_enabled() &&
+ strcmp(f->name, "etc/vmcoreinfo") == 0 && !is_kdump_kernel()) {
+ if (write_vmcoreinfo(dev, f) < 0)
+ pr_warn("fw_cfg: failed to write vmcoreinfo");
+ }
+#endif
+
/* allocate new entry */
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
if (!entry)
--
2.16.0.rc1.1.gef27df75a1
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