[tests] Skip some flaky and unreliable LTP tests

Signed-off-by: Michał Kowalczyk <mkow@invisiblethingslab.com>

LibOS/shim/test/ltp/ltp.cfg

@@ -152,6 +152,11 @@ must-pass =
     13
     14
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[clock_nanosleep02]
+skip = yes
+
 # kernel config
 [clock_nanosleep03]
 skip = yes
@@ -227,6 +232,11 @@ skip = yes
 [epoll_pwait01]
 skip = yes
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[epoll_wait02]
+skip = yes
+
 # test requires libaio
 [eventfd01]
 skip = yes
@@ -594,6 +604,11 @@ skip = yes
 [futex_wait03]
 skip = yes
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[futex_wait05]
+skip = yes
+
 # opens /proc/2/task
 [futex_wake02]
 skip = yes
@@ -1206,6 +1221,11 @@ skip = yes
 [munlockall01]
 skip = yes
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[nanosleep01]
+skip = yes
+
 # reports TBROK due to lack of reported results (no shared memory in Graphene)
 [nanosleep02]
 must-pass =
@@ -1353,7 +1373,7 @@ skip = yes
 [pipe2_02]
 skip = yes
 
-# fails to set O_NONBLOCK by using pipe2(fds, O_NONBLOCK)
+# requires support for F_SETPIPE_SZ in fcntl
 [pipe2_04]
 skip = yes
 
@@ -1364,6 +1384,11 @@ skip = yes
 [pkey*]
 skip = yes
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[poll02]
+skip = yes
+
 [posix_fadvise01]
 skip = yes
 
@@ -1494,6 +1519,16 @@ skip = yes
 [prot_hsymlinks]
 skip = yes
 
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[pselect01]
+skip = yes
+
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
+[pselect01_64]
+skip = yes
+
 # no ptrace()
 [ptrace*]
 skip = yes
@@ -1813,7 +1848,9 @@ skip = yes
 [sched_setscheduler03]
 skip = yes
 
-# relies on shared mmap (see tst_test.c:setup_ipc)
+# Relies on shared mmap (see tst_test.c:setup_ipc).
+# Requires disabling C-states through /dev/cpu_dma_latency to work reliably. See
+# https://github.com/linux-test-project/ltp/issues/862.
 [select04]
 skip = yes