| Message ID | 168193567363.1178687.9185773070266307121.stgit@djiang5-mobl3 |
|---|---|
| State | New |
| Headers | show |
| Series | cxl: Add support for QTG ID retrieval for CXL subsystem | expand |
On Wed, 19 Apr 2023 13:21:13 -0700 Dave Jiang <dave.jiang@intel.com> wrote: > A CDAT table is available from a CXL device. The table is read by the > driver and cached in software. With the CXL subsystem needing to parse the > CDAT table, the checksum should be verified. Add checksum verification > after the CDAT table is read from device. > > Reviewed-by: Ira Weiny <ira.weiny@intel.com> > Signed-off-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > > --- > v3: > - Just return the final sum. (Alison) > v2: > - Drop ACPI checksum export and just use local verification. (Dan) > --- > drivers/cxl/core/pci.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 25b7e8125d5d..9c7e2f69d9ca 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -528,6 +528,16 @@ static int cxl_cdat_read_table(struct device *dev, > return 0; > } > > +static unsigned char cdat_checksum(void *buf, size_t size) > +{ > + unsigned char sum, *data = buf; > + size_t i; > + > + for (sum = 0, i = 0; i < size; i++) > + sum += data[i]; > + return sum; > +} > + > /** > * read_cdat_data - Read the CDAT data on this port > * @port: Port to read data from > @@ -573,6 +583,12 @@ void read_cdat_data(struct cxl_port *port) > } > > port->cdat.table = cdat_table + sizeof(__le32); > + if (cdat_checksum(port->cdat.table, cdat_length)) { > + /* Don't leave table data allocated on error */ > + devm_kfree(dev, cdat_table); > + dev_err(dev, "CDAT data checksum error\n"); > + } > + > port->cdat.length = cdat_length; > } > EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL); > >
Dave Jiang wrote: > A CDAT table is available from a CXL device. The table is read by the > driver and cached in software. With the CXL subsystem needing to parse the > CDAT table, the checksum should be verified. Add checksum verification > after the CDAT table is read from device. > > Reviewed-by: Ira Weiny <ira.weiny@intel.com> > Signed-off-by: Dave Jiang <dave.jiang@intel.com> > > --- > v3: > - Just return the final sum. (Alison) > v2: > - Drop ACPI checksum export and just use local verification. (Dan) > --- > drivers/cxl/core/pci.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c > index 25b7e8125d5d..9c7e2f69d9ca 100644 > --- a/drivers/cxl/core/pci.c > +++ b/drivers/cxl/core/pci.c > @@ -528,6 +528,16 @@ static int cxl_cdat_read_table(struct device *dev, > return 0; > } > > +static unsigned char cdat_checksum(void *buf, size_t size) > +{ > + unsigned char sum, *data = buf; > + size_t i; > + > + for (sum = 0, i = 0; i < size; i++) > + sum += data[i]; > + return sum; > +} > + > /** > * read_cdat_data - Read the CDAT data on this port > * @port: Port to read data from > @@ -573,6 +583,12 @@ void read_cdat_data(struct cxl_port *port) > } > > port->cdat.table = cdat_table + sizeof(__le32); > + if (cdat_checksum(port->cdat.table, cdat_length)) { > + /* Don't leave table data allocated on error */ > + devm_kfree(dev, cdat_table); > + dev_err(dev, "CDAT data checksum error\n"); > + } > + > port->cdat.length = cdat_length; I think read_cdat_data() is confused about error cases. I note that /sys/firmware/acpi/tables does not emit the entry if the table has bad length or bad checksum. If you want to have a debug mode then maybe make it a compile time option, but I otherwise do not see the benefit of publishing known bad tables to userspace.
On 4/24/23 3:01 PM, Dan Williams wrote: > Dave Jiang wrote: >> A CDAT table is available from a CXL device. The table is read by the >> driver and cached in software. With the CXL subsystem needing to parse the >> CDAT table, the checksum should be verified. Add checksum verification >> after the CDAT table is read from device. >> >> Reviewed-by: Ira Weiny <ira.weiny@intel.com> >> Signed-off-by: Dave Jiang <dave.jiang@intel.com> >> >> --- >> v3: >> - Just return the final sum. (Alison) >> v2: >> - Drop ACPI checksum export and just use local verification. (Dan) >> --- >> drivers/cxl/core/pci.c | 16 ++++++++++++++++ >> 1 file changed, 16 insertions(+) >> >> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c >> index 25b7e8125d5d..9c7e2f69d9ca 100644 >> --- a/drivers/cxl/core/pci.c >> +++ b/drivers/cxl/core/pci.c >> @@ -528,6 +528,16 @@ static int cxl_cdat_read_table(struct device *dev, >> return 0; >> } >> >> +static unsigned char cdat_checksum(void *buf, size_t size) >> +{ >> + unsigned char sum, *data = buf; >> + size_t i; >> + >> + for (sum = 0, i = 0; i < size; i++) >> + sum += data[i]; >> + return sum; >> +} >> + >> /** >> * read_cdat_data - Read the CDAT data on this port >> * @port: Port to read data from >> @@ -573,6 +583,12 @@ void read_cdat_data(struct cxl_port *port) >> } >> >> port->cdat.table = cdat_table + sizeof(__le32); >> + if (cdat_checksum(port->cdat.table, cdat_length)) { >> + /* Don't leave table data allocated on error */ >> + devm_kfree(dev, cdat_table); >> + dev_err(dev, "CDAT data checksum error\n"); >> + } >> + >> port->cdat.length = cdat_length; > > I think read_cdat_data() is confused about error cases. I note that > /sys/firmware/acpi/tables does not emit the entry if the table has bad > length or bad checksum. If you want to have a debug mode then maybe make > it a compile time option, but I otherwise do not see the benefit of > publishing known bad tables to userspace. I'll have it return on errors.
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c index 25b7e8125d5d..9c7e2f69d9ca 100644 --- a/drivers/cxl/core/pci.c +++ b/drivers/cxl/core/pci.c @@ -528,6 +528,16 @@ static int cxl_cdat_read_table(struct device *dev, return 0; } +static unsigned char cdat_checksum(void *buf, size_t size) +{ + unsigned char sum, *data = buf; + size_t i; + + for (sum = 0, i = 0; i < size; i++) + sum += data[i]; + return sum; +} + /** * read_cdat_data - Read the CDAT data on this port * @port: Port to read data from @@ -573,6 +583,12 @@ void read_cdat_data(struct cxl_port *port) } port->cdat.table = cdat_table + sizeof(__le32); + if (cdat_checksum(port->cdat.table, cdat_length)) { + /* Don't leave table data allocated on error */ + devm_kfree(dev, cdat_table); + dev_err(dev, "CDAT data checksum error\n"); + } + port->cdat.length = cdat_length; } EXPORT_SYMBOL_NS_GPL(read_cdat_data, CXL);