On 10/08/19 23:58, Laszlo Ersek wrote: > On 10/07/19 19:55, Philippe Mathieu-Daudé wrote: >> On 10/7/19 7:35 PM, John Snow wrote: >>> On 10/7/19 8:33 AM, Peter Maydell wrote: >>>> On Thu, 3 Oct 2019 at 20:33, John Snow <js...@redhat.com> wrote: >>>>> >>>>> The following changes since commit >>>>> 7f21573c822805a8e6be379d9bcf3ad9effef3dc: >>>>> >>>>> Merge remote-tracking branch >>>>> 'remotes/huth-gitlab/tags/pull-request-2019-10-01' into staging >>>>> (2019-10-01 13:13:38 +0100) >>>>> >>>>> are available in the Git repository at: >>>>> >>>>> https://github.com/jnsnow/qemu.git tags/ide-pull-request >>>>> >>>>> for you to fetch changes up to >>>>> f6d61c9509c56eea3cdd2d23b40d285601b1c1ca: >>>>> >>>>> hd-geo-test: Add tests for lchs override (2019-10-03 14:36:54 -0400) >>>>> >>>>> ---------------------------------------------------------------- >>>>> Pull request V2 >>>>> >>>>> - Added signoff into the mirrored commits themselves (vs just the >>>>> email) >>>>> - Kudos to `stg-foreach stg edit --sign` >>>>> >>>>> ---------------------------------------------------------------- >>>> >>>> Hi; the new tests in hd-geo-test seem to hang on >>>> big-endian hosts (both s390x and ppc64 hung here): >>>> >>>> linux1@lxub05:~/qemu/build/all$ QTEST_QEMU_IMG=./qemu-img >>>> QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64 >>>> ./tests/hd-geo-test >>>> /x86_64/hd-geo/ide/none: OK >>>> /x86_64/hd-geo/ide/drive/cd_0: OK >>>> /x86_64/hd-geo/ide/drive/mbr/blank: OK >>>> /x86_64/hd-geo/ide/drive/mbr/lba: OK >>>> /x86_64/hd-geo/ide/drive/mbr/chs: OK >>>> /x86_64/hd-geo/ide/device/mbr/blank: OK >>>> /x86_64/hd-geo/ide/device/mbr/lba: OK >>>> /x86_64/hd-geo/ide/device/mbr/chs: OK >>>> /x86_64/hd-geo/ide/device/user/chs: OK >>>> /x86_64/hd-geo/ide/device/user/chst: OK >>>> /x86_64/hd-geo/override/ide: >>>> >>> >>> :( >>> >>>> >>>> thanks >>>> -- PMM >>>> >>> >>> Sam, can you investigate this? >> >> Not seeing my T-b tags makes me grumble because I don't remember which I >> reviewed and need to go check on the list. >> >> If the error is a endianess bug related to fw_cfg, you can add the >> "-trace fw_cfg*" in hd-geo-test::create_args() and rerun the tests on a >> BE system, the bug should appear straightly on stdout. >> >> Are FWLCHSEntry fields little-endian? Shouldn't >> get_boot_devices_lchs_list() use some le32_to_cpu() call for the LCHS >> values? >> > > *One* problem is most likely in the find_fw_cfg_file() function, in patch 8. > > +static uint16_t find_fw_cfg_file(QFWCFG *fw_cfg, > + const char *filename) > +{ > + struct QemuCfgFile qfile; > + uint32_t count, e; > + uint16_t select; > + > + count = qfw_cfg_get_u32(fw_cfg, FW_CFG_FILE_DIR); > + count = be32_to_cpu(count); > + for (select = 0, e = 0; e < count; e++) { > + qfw_cfg_read_data(fw_cfg, &qfile, sizeof(qfile)); > + if (!strcmp(filename, qfile.name)) { > + select = be16_to_cpu(qfile.select); > + } > + } > + > + return select; > +} > > Note qfw_cfg_get_u32(): > > uint32_t qfw_cfg_get_u32(QFWCFG *fw_cfg, uint16_t key) > { > uint32_t value; > qfw_cfg_get(fw_cfg, key, &value, sizeof(value)); > return le32_to_cpu(value); > } > > This function assumes that the wire encoding of the value read is little > endian. So, calling this function is wrong; and calling be32_to_cpu() > afterwards does not help. Namely: > > * On LE hosts, the find_fw_cfg_file() function happens to work, because: > > - the le32_to_cpu() call in qfw_cfg_get_u32() does nothing (it's identity), > - the subsequent be32_to_cpu() call in find_fw_cfg_file() corresponds to > the *blob-specific* encoding of the "count" field, in the fw_cfg > directory blob. (Which is BE) Therefore we perform the one byte-swap > that we need. > > * On BE hosts, stuff breaks, because: > > - the le32_to_cpu() call in qfw_cfg_get_u32() swaps the byte-order, > - the subsequent be32_to_cpu() call in find_fw_cfg_file() does nothing, > - thus, ultimately we have byte-swapped the contents of the "count" > field of the directory blob, even though the blob-specific wire format > thereof is *already* BE (= host-endian). On a BE host, all in all, there > should be zero byte swaps for consuming "count".
And the hang is probably due to the loop in find_fw_cfg_file() counting up to cca. 0x2000_0000: - The file directory currently has room for 0x20 files, and if you byte-swap that as a uint32_t, you get 0x2000_0000. (You minimally get 0x0100_0000, if there's just one entry in the directory -- still 16,777,216 in decimal.) - Additionally, the loop body does not contain a "break" statement for when strcmp() matches; so even if there is a hit in the low numbers, the loop continues to the limit. Thanks Laszlo > Now, how to fix this: eliminate > - QemuCfgFile, > - find_fw_cfg_file(), > - and read_fw_cfg_file() > > altogether, and call qfw_cfg_get_file(), from "tests/libqos/fw_cfg.c". > > Some other tests look up fw_cfg directory entries with that function > already (see call sites in "tests/fw_cfg-test.c"). > > Thanks > Laszlo >