On 2020/1/2 18:20, Shameerali Kolothum Thodi wrote: > 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 for the reminding, I noticed acpi_match_platform_list() before but I thought it was a little overkill (get the table header for each OEM info), I will take a look further to see if I can consolidate the OEM information retrieve. Thanks Hanjun
