[PATCH 6.1 171/197] selftests/mm: Update va_high_addr_switch.sh to check CPU for la57 flag

Greg Kroah-Hartman
2024-02-20T21:08:26Z

From: Audra Mitchell <audra@redhat.com>

[ Upstream commit 52e63d67b5bb423b33d7a262ac7f8bd375a90145 ]

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: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/vm/va_128TBswitch.sh | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/tools/testing/selftests/vm/va_128TBswitch.sh b/tools/testing/selftests/vm/va_128TBswitch.sh
index 41580751dc51..231622b3a232 100755
--- a/tools/testing/selftests/vm/va_128TBswitch.sh
+++ b/tools/testing/selftests/vm/va_128TBswitch.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
}

--
2.43.0