Hi Hanjun, > -----Original Message----- > From: Linuxarm [mailto:linuxarm-bounces@xxxxxxxxxx] On Behalf Of Hanjun > Guo > Sent: 23 December 2019 09:23 > To: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>; Sudeep Holla > <sudeep.holla@xxxxxxx>; Rafael J. Wysocki <rafael@xxxxxxxxxx>; Pankaj > Bansal <pankaj.bansal@xxxxxxx>; Erik Schmauss <erik.schmauss@xxxxxxxxx> > Cc: linux-acpi@xxxxxxxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Subject: [RFC PATCH 2/2] ACPI/IORT: Workaround for IORT ID count "minus > one" issue > > The IORT spec [0] says Number of IDs = The number of IDs in the range minus > one, it is confusing but it was written down in the first version of the > IORT spec. But the IORT ID mapping function iort_id_map() did something > wrong from the start, which bails out if: > > the request ID >= the input base + number of IDs > > This is wrong because it ignored the "minus one", and breaks some valid > usecases such as ID mapping to contain single device mapping without > single mapping flag set. > > Pankaj Bansal proposed a solution to fix the issue [1], which bails > out if: > > the request ID > the input base + number of IDs > > This works as the spec defined, unfortunately some firmware didn't > minus one for the number of IDs in the range, and the propoased > solution will break those systems in this way: > > PCI hostbridge mapping entry 1: > Input base: 0x1000 > ID Count: 0x100 > Output base: 0x1000 > Output reference: 0xC4 //ITS reference > > PCI hostbridge mapping entry 2: > Input base: 0x1100 > ID Count: 0x100 > Output base: 0x2000 > Output reference: 0xD4 //ITS reference > > Two mapping entries which the second entry's Input base = the first > entry's Input base + ID count, so for requester ID 0x1100 will map > to ITS 0xC4 not 0xD4 if we update '>=' to '>'. > > So introduce a workaround to match the IORT's OEM information for > the broken firmware, also update the logic of the ID mapping for > firmwares report the number of IDs as the IORT spec defined, to > make the code compatible for both kinds of system. > > I checked the ACPI tables in the tianocore/edk2-platforms [2], only > HiSilicon HIP07/08 did wrong, so just add HIP07/08 to the workaround > info table, if we break other platforms, we can add that later. > > [0]: > http://infocenter.arm.com/help/topic/com.arm.doc.den0049d/DEN0049D_IO_ > Remapping_Table.pdf > [1]: https://patchwork.kernel.org/patch/11292823/ > [2]: https://github.com/tianocore/edk2-platforms > > Cc: Pankaj Bansal <pankaj.bansal@xxxxxxx> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> > Signed-off-by: Hanjun Guo <guohanjun@xxxxxxxxxx> > --- > drivers/acpi/arm64/iort.c | 54 > ++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 51 insertions(+), 3 deletions(-) > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index 33f7198..112b1b0 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -298,6 +298,41 @@ static acpi_status iort_match_node_callback(struct > acpi_iort_node *node, > return status; > } > > +struct iort_workaround_oem_info { > + char oem_id[ACPI_OEM_ID_SIZE + 1]; > + char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1]; > + u32 oem_revision; > +}; > + > +static bool apply_id_count_workaround; > + > +static struct iort_workaround_oem_info wa_info[] __initdata = { > + { > + .oem_id = "HISI ", > + .oem_table_id = "HIP07 ", > + .oem_revision = 0, > + }, { > + .oem_id = "HISI ", > + .oem_table_id = "HIP08 ", > + .oem_revision = 0, > + } > +}; > + > +static void __init > +iort_check_id_count_workaround(struct acpi_table_header *tbl) > +{ > + int i; > + > + for (i = 0; i < ARRAY_SIZE(wa_info); i++) { > + if (!memcmp(wa_info[i].oem_id, tbl->oem_id, ACPI_OEM_ID_SIZE) > && > + !memcmp(wa_info[i].oem_table_id, tbl->oem_table_id, > ACPI_OEM_TABLE_ID_SIZE) && > + wa_info[i].oem_revision == tbl->oem_revision) { > + apply_id_count_workaround = true; > + break; > + } > + } > +} > + Can we get rid of the above and instead use acpi_match_platform_list() ? Please take a look at the pmcg_plat_info used for the HIP08 SMMUv3 PMCG erratum. Thanks, Shameer > static int iort_id_map(struct acpi_iort_id_mapping *map, u8 type, u32 rid_in, > u32 *rid_out) > { > @@ -314,9 +349,21 @@ static int iort_id_map(struct acpi_iort_id_mapping > *map, u8 type, u32 rid_in, > return -ENXIO; > } > > - if (rid_in < map->input_base || > - (rid_in >= map->input_base + map->id_count)) > - return -ENXIO; > + /* > + * IORT spec says Number of IDs = The number of IDs in the range minus > + * one, but the IORT code ingored the "minus one", and some firmware > + * did that too, so apply a workaround here to keep compatible with > + * both new and old versions of the firmware. > + */ > + if (apply_id_count_workaround) { > + if (rid_in < map->input_base || > + (rid_in >= map->input_base + map->id_count)) > + return -ENXIO; > + } else { > + if (rid_in < map->input_base || > + (rid_in > map->input_base + map->id_count)) > + return -ENXIO; > + } > > *rid_out = map->output_base + (rid_in - map->input_base); > return 0; > @@ -1631,5 +1678,6 @@ void __init acpi_iort_init(void) > return; > } > > + iort_check_id_count_workaround(iort_table); > iort_init_platform_devices(); > } > -- > 1.7.12.4 > > _______________________________________________ > Linuxarm mailing list > Linuxarm@xxxxxxxxxx > http://hulk.huawei.com/mailman/listinfo/linuxarm
