On Mon, Mar 20, 2023 at 10:21 PM Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> wrote: > > The Confidential Computing Event Log (CCEL) table provides the address > and length of the CCEL records area in UEFI reserved memory. The rest of this paragraph can be omitted. > To access > these records, userspace can use /dev/mem to retrieve them. But > '/dev/mem' is not enabled on many systems for security reasons. > > So to allow user space access these event log records without the > /dev/mem interface, add support to access it via sysfs interface. The > ACPI driver has provided read only access to BERT records area via > '/sys/firmware/acpi/tables/data/BERT' in sysfs. So follow the same way, > and add support for /sys/firmware/acpi/tables/data/CCEL to enable > read-only access to the CCEL recorids area. > > More details about the CCEL table can be found in ACPI specification > r6.5, sec titled "CC Event Log ACPI Table". Please provide a proper section number here and a Link: tag pointing to the relevant section of the spec (which is https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#cc-event-log-acpi-table I think). > Original-patch-by: Haibo Xu <haibo1.xu@xxxxxxxxx> If the original patch has been signed-off by that developer, you can use a Co-developed-by: along with the original S-o-b tag here. > [Original patch is for TDEL table, modified it for CCEL support] > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> > --- > > Changes since v1: > * Removed unnecessary parenthesis as per Rafael's suggestion.. > > drivers/acpi/sysfs.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c > index 7f4ff56c9d42..687524b50085 100644 > --- a/drivers/acpi/sysfs.c > +++ b/drivers/acpi/sysfs.c > @@ -458,11 +458,28 @@ static int acpi_bert_data_init(void *th, struct acpi_data_attr *data_attr) > return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr); > } > > +static int acpi_ccel_data_init(void *th, struct acpi_data_attr *data_attr) > +{ > + struct acpi_table_ccel *ccel = th; > + > + if (ccel->header.length < sizeof(struct acpi_table_ccel) || > + !ccel->log_area_start_address || !ccel->log_area_minimum_length) { > + kfree(data_attr); > + return -EINVAL; > + } > + data_attr->addr = ccel->log_area_start_address; > + data_attr->attr.size = ccel->log_area_minimum_length; > + data_attr->attr.attr.name = "CCEL"; > + > + return sysfs_create_bin_file(tables_data_kobj, &data_attr->attr); > +} > + > static struct acpi_data_obj { > char *name; > int (*fn)(void *, struct acpi_data_attr *); > } acpi_data_objs[] = { > { ACPI_SIG_BERT, acpi_bert_data_init }, > + { ACPI_SIG_CCEL, acpi_ccel_data_init }, > }; > > #define NUM_ACPI_DATA_OBJS ARRAY_SIZE(acpi_data_objs) > -- > 2.34.1 >
