Messages in this thread | | | Date | Thu, 16 Nov 2017 18:05:10 +0200 | From | "Michael S. Tsirkin" <> | Subject | Re: [PATCH v6 5/5] fw_cfg: write vmcoreinfo details |
| |
On Thu, Nov 16, 2017 at 08:34:23AM -0500, Marc-André Lureau wrote: > Hi > > ----- Original Message ----- > > On Mon, Nov 13, 2017 at 08:29:58PM +0100, Marc-André Lureau wrote: > > > 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 | 87 > > > +++++++++++++++++++++++++++++++++++++++++- > > > 1 file changed, 86 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/firmware/qemu_fw_cfg.c > > > b/drivers/firmware/qemu_fw_cfg.c > > > index 2ac4cd869fe6..7a70e7a549f6 100644 > > > --- a/drivers/firmware/qemu_fw_cfg.c > > > +++ b/drivers/firmware/qemu_fw_cfg.c > > > @@ -35,6 +35,8 @@ > > > #include <linux/ioport.h> > > > #include <linux/delay.h> > > > #include <linux/dma-mapping.h> > > > +#include <linux/crash_core.h> > > > +#include <linux/crash_dump.h> > > > > > > MODULE_AUTHOR("Gabriel L. Somlo <somlo@cmu.edu>"); > > > MODULE_DESCRIPTION("QEMU fw_cfg sysfs support"); > > > @@ -59,6 +61,8 @@ 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 > > > + > > > /* platform device for dma mapping */ > > > static struct device *dev; > > > > > > @@ -127,7 +131,8 @@ static ssize_t fw_cfg_dma_transfer(void *address, u32 > > > length, u32 control) > > > dma_addr_t dma; > > > ssize_t ret = length; > > > enum dma_data_direction dir = > > > - (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0); > > > + (control & FW_CFG_DMA_CTL_READ ? DMA_FROM_DEVICE : 0) | > > > + (control & FW_CFG_DMA_CTL_WRITE ? DMA_TO_DEVICE : 0); > > > > > > if (address && length) { > > > dma_addr = dma_map_single(dev, address, length, dir); > > > @@ -225,6 +230,48 @@ static ssize_t fw_cfg_read_blob(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(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__); > > > + memset(buf, 0, count); > > > + return -EINVAL; > > > + } > > > + > > > + mutex_lock(&fw_cfg_dev_lock); > > > + if (pos == 0) { > > > + ret = fw_cfg_dma_transfer(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(NULL, pos, FW_CFG_DMA_CTL_SKIP); > > > + if (ret < 0) > > > + goto end; > > > + ret = fw_cfg_dma_transfer(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) > > > { > > > @@ -343,6 +390,37 @@ struct fw_cfg_sysfs_entry { > > > struct list_head list; > > > }; > > > > > > +#ifdef CONFIG_CRASH_CORE > > > +static ssize_t write_vmcoreinfo(const struct fw_cfg_file *f) > > > +{ > > > + struct vmci { > > > + __le16 host_format; > > > + __le16 guest_format; > > > + __le32 size; > > > + __le64 paddr; > > > + } __packed; > > > + struct vmci *data; > > > + ssize_t ret; > > > + > > > + data = kmalloc(sizeof(struct vmci), GFP_KERNEL | GFP_DMA); > > > + if (!data) > > > + return -ENOMEM; > > > > It's a small bit of data - you can just keep it in a global variable, > > this way failures won't be an issue. > > It would still need to be allocated
No - you can just make it a global variable.
> with GFP_DMA.
Are you sure?
* GFP_DMA exists for historical reasons and should be avoided where possible. * The flags indicates that the caller requires that the lowest zone be * used (ZONE_DMA or 16M on x86-64). Ideally, this would be removed but * it would require careful auditing as some users really require it and * others use the flag to avoid lowmem reserves in ZONE_DMA and treat the * lowest zone as a type of emergency reserve.
> Since it's a one time thing, this is just moving the problem isn't it?
Isn't the timeout just moving the problem too? Avoiding memory corruption is a priority.
> > > > > + > > > + /* spare ourself reading host format support for now since we > > > + * don't know what else to format - host may ignore ours > > > + */ > > > + *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()) > > > + }; > > > + ret = fw_cfg_write_blob(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) > > > { > > > @@ -582,6 +660,13 @@ static int fw_cfg_register_file(const struct > > > fw_cfg_file *f) > > > int err; > > > struct fw_cfg_sysfs_entry *entry; > > > > > > +#ifdef CONFIG_CRASH_CORE > > > + if (strcmp(f->name, "etc/vmcoreinfo") == 0 && !is_kdump_kernel()) { > > > + if (write_vmcoreinfo(f) < 0) > > > + pr_warn("fw_cfg: failed to write vmcoreinfo"); > > > + } > > > +#endif > > > + > > > /* allocate new entry */ > > > entry = kzalloc(sizeof(*entry), GFP_KERNEL); > > > if (!entry) > > > -- > > > 2.15.0.125.g8f49766d64 > >
| |