# git rev-parse -q --verify 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479^{commit} 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479 already have revision, skipping fetch # git checkout -q -f -B kisskb 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479 # git clean -qxdf # < git log -1 # commit 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479 # Author: Suraj Jitindar Singh # Date: Thu Jun 20 11:46:51 2019 +1000 # # KVM: PPC: Book3S HV: Clear pending decrementer exceptions on nested guest entry # # If we enter an L1 guest with a pending decrementer exception then this # is cleared on guest exit if the guest has writtien a positive value # into the decrementer (indicating that it handled the decrementer # exception) since there is no other way to detect that the guest has # handled the pending exception and that it should be dequeued. In the # event that the L1 guest tries to run a nested (L2) guest immediately # after this and the L2 guest decrementer is negative (which is loaded # by L1 before making the H_ENTER_NESTED hcall), then the pending # decrementer exception isn't cleared and the L2 entry is blocked since # L1 has a pending exception, even though L1 may have already handled # the exception and written a positive value for it's decrementer. This # results in a loop of L1 trying to enter the L2 guest and L0 blocking # the entry since L1 has an interrupt pending with the outcome being # that L2 never gets to run and hangs. # # Fix this by clearing any pending decrementer exceptions when L1 makes # the H_ENTER_NESTED hcall since it won't do this if it's decrementer # has gone negative, and anyway it's decrementer has been communicated # to L0 in the hdec_expires field and L0 will return control to L1 when # this goes negative by delivering an H_DECREMENTER exception. # # Fixes: 95a6432ce903 ("KVM: PPC: Book3S HV: Streamlined guest entry/exit path on P9 for radix guests") # Cc: stable@vger.kernel.org # v4.20+ # Signed-off-by: Suraj Jitindar Singh # Signed-off-by: Michael Ellerman # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479 # < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_83xx_mpc832x_mds_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- 83xx/mpc832x_mds_defconfig # make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-next_83xx_mpc832x_mds_defconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/kernel/futex.c: In function 'do_futex': /kisskb/src/kernel/futex.c:1658:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval == cmparg; ^ /kisskb/src/kernel/futex.c:1633:6: note: 'oldval' was declared here int oldval, ret; ^ INFO: Uncompressed kernel (size 0x52663c) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x600000) INFO: Uncompressed kernel (size 0x515f24) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x600000) Image Name: Linux-5.2.0-rc2-g3c25ab35fbc8 Created: Fri Jun 21 01:43:38 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2588075 Bytes = 2527.42 KiB = 2.47 MiB Load Address: 00000000 Entry Point: 00000000 Image Name: Linux-5.2.0-rc2-g3c25ab35fbc8 Created: Fri Jun 21 01:43:38 2019 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2617474 Bytes = 2556.13 KiB = 2.50 MiB Load Address: 00600000 Entry Point: 00600294 Completed OK # rm -rf /kisskb/build/powerpc-next_83xx_mpc832x_mds_defconfig_powerpc-gcc5 # Build took: 0:00:23.148811