On Wed, Mar 22, 2023 at 8:00 PM Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> wrote: > > Hi Rafael, > > On 3/22/23 11:31 AM, Rafael J. Wysocki wrote: > > 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> > >> --- > >> > > How about the following version? Looks good to me, thanks! > ACPI: sysfs: Enable ACPI sysfs support for CCEL records > > The Confidential Computing Event Log (CCEL) table provides the address > and length of the CCEL records area in UEFI reserved memory. > > To allow user space access to these records, expose a sysfs interface > similar to the BERT table. > > More details about the CCEL table can be found in the ACPI specification > r6.5 [1], sec 5.2.34. > > Link: https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html#cc-event-log-acpi-table # [1] > Co-developed-by: Haibo Xu <haibo1.xu@xxxxxxxxx> > Signed-off-by: Haibo Xu <haibo1.xu@xxxxxxxxx> > 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 > >> > > -- > Sathyanarayanan Kuppuswamy > Linux Kernel Developer
