6.6-stable review patch. If anyone has any objections, please let me know.
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From: Audra Mitchell audra@redhat.com
commit 52e63d67b5bb423b33d7a262ac7f8bd375a90145 upstream.
In order for the page table level 5 to be in use, the CPU must have the setting enabled in addition to the CONFIG option. Check for the flag to be set to avoid false test failures on systems that do not have this cpu flag set.
The test does a series of mmap calls including three using the MAP_FIXED flag and specifying an address that is 1<<47 or 1<<48. These addresses are only available if you are using level 5 page tables, which requires both the CPU to have the capabiltiy (la57 flag) and the kernel to be configured. Currently the test only checks for the kernel configuration option, so this test can still report a false positive. Here are the three failing lines:
$ ./va_high_addr_switch | grep FAILED mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED): 0xffffffffffffffff - FAILED mmap(HIGH_ADDR, MAP_FIXED): 0xffffffffffffffff - FAILED mmap(ADDR_SWITCH_HINT, 2 * PAGE_SIZE, MAP_FIXED): 0xffffffffffffffff - FAILED
I thought (for about a second) refactoring the test so that these three mmap calls will only be run on systems with the level 5 page tables available, but the whole point of the test is to check the level 5 feature...
Link: https://lkml.kernel.org/r/20240119205801.62769-1-audra@redhat.com Fixes: 4f2930c6718a ("selftests/vm: only run 128TBswitch with 5-level paging") Signed-off-by: Audra Mitchell audra@redhat.com Cc: Rafael Aquini raquini@redhat.com Cc: Shuah Khan shuah@kernel.org Cc: Adam Sindelar adam@wowsignal.io Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/testing/selftests/mm/va_high_addr_switch.sh | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/tools/testing/selftests/mm/va_high_addr_switch.sh +++ b/tools/testing/selftests/mm/va_high_addr_switch.sh @@ -29,9 +29,15 @@ check_supported_x86_64() # See man 1 gzip under '-f'. local pg_table_levels=$(gzip -dcfq "${config}" | grep PGTABLE_LEVELS | cut -d'=' -f 2)
+ local cpu_supports_pl5=$(awk '/^flags/ {if (/la57/) {print 0;} + else {print 1}; exit}' /proc/cpuinfo 2>/dev/null) + if [[ "${pg_table_levels}" -lt 5 ]]; then echo "$0: PGTABLE_LEVELS=${pg_table_levels}, must be >= 5 to run this test" exit $ksft_skip + elif [[ "${cpu_supports_pl5}" -ne 0 ]]; then + echo "$0: CPU does not have the necessary la57 flag to support page table level 5" + exit $ksft_skip fi }