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SubjectRe: [PATCH v11 4/4] fw_cfg: write vmcoreinfo details
Hi

On Fri, Feb 2, 2018 at 3:44 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Thu, Feb 01, 2018 at 02:03:00PM +0100, Marc-André Lureau wrote:
>> @@ -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)
>> {
>
> kmalloc during crash is I think a bad idea.
> How about preallocating on probe?

It doesn't kmalloc during crash, it kmalloc during boot. As such, I
don't see a reason to change it.

>
> diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
> index 33e0256..ffd81d1 100644
> --- a/drivers/firmware/qemu_fw_cfg.c
> +++ b/drivers/firmware/qemu_fw_cfg.c
> @@ -363,22 +363,33 @@ struct fw_cfg_sysfs_entry {
> };
>
> #ifdef CONFIG_CRASH_CORE
> +
> +struct vmci {
> + __le16 host_format;
> + __le16 guest_format;
> + __le32 size;
> + __le64 paddr;
> +} *fw_cfg_vmcore_data;
> +
> +static int fw_cfg_vmcore_init(void)
> +{
> + fw_cfg_vmcore_data = kmalloc(sizeof(*fw_cfg_vmcore_data), GFP_KERNEL);
> + if (!fw_cfg_vmcore_data)
> + return -ENOMEM;
> + return 0;
> +}
> +
> +static int fw_cfg_vmcore_cleanup(void)
> +{
> + kfree(fw_cfg_vmcore_data);
> +}
> +
> 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) {
> + *fw_cfg_vmcore_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())
> @@ -386,11 +397,23 @@ static ssize_t write_vmcoreinfo(struct device *dev, const struct fw_cfg_file *f)
> /* 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));
> + ret = fw_cfg_write_blob(dev, f->select, fw_cfg_vmcore_data, 0,
> + sizeof(*fw_cfg_vmcore_data));
>
> - kfree(data);
> return ret;
> }
> +
> +#else
> +
> +static int fw_cfg_vmcore_init(void)
> +{
> + return 0;
> +}
> +
> +static int fw_cfg_vmcore_cleanup(void)
> +{
> +}
> +
> #endif /* CONFIG_CRASH_CORE */
>
> /* get fw_cfg_sysfs_entry from kobject member */
> @@ -725,11 +748,15 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
> if (fw_cfg_sel_ko)
> return -EBUSY;
>
> + err = fw_cfg_vmcore_init();
> + if (err)
> + goto err_sel;
> +
> /* 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);
> if (!fw_cfg_sel_ko)
> - goto err_sel;
> + goto err_vmcore;
> fw_cfg_fname_kset = kset_create_and_add("by_name", NULL, fw_cfg_top_ko);
> if (!fw_cfg_fname_kset)
> goto err_name;
> @@ -764,6 +791,8 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev)
> fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
> err_name:
> fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
> +err_vmcore:
> + fw_cfg_vmcore_cleanup();
> err_sel:
> return err;
> }
> @@ -776,6 +805,7 @@ static int fw_cfg_sysfs_remove(struct platform_device *pdev)
> fw_cfg_io_cleanup();
> fw_cfg_kset_unregister_recursive(fw_cfg_fname_kset);
> fw_cfg_kobj_cleanup(fw_cfg_sel_ko);
> + fw_cfg_vmcore_cleanup();
> return 0;
> }
>

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