# 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 <sjitindarsingh@gmail.com>
# 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 <sjitindarsingh@gmail.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-gcc --version
# < /opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-ld --version
# < git log --format=%s --max-count=1 3c25ab35fbc8526ac0c9b298e8a78e7ad7a55479
# < make -s -j 120 ARCH=sparc64 O=/kisskb/build/powerpc-next_sparc64-defconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-  defconfig
# make -s -j 120 ARCH=sparc64 O=/kisskb/build/powerpc-next_sparc64-defconfig_sparc64 CROSS_COMPILE=/opt/cross/kisskb/br-sparc64-full-2016.08-613-ge98b4dd/bin/sparc64-linux-  
/kisskb/src/net/ipv4/fib_semantics.c: In function 'fib_check_nh_v4_gw':
/kisskb/src/net/ipv4/fib_semantics.c:1027:12: warning: 'err' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (!tbl || err) {
            ^
WARNING: EXPORT symbol "_mcount" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: EXPORT symbol "_mcount" [vmlinux] version generation failed, symbol will not be versioned.
  kernel: arch/sparc/boot/image is ready
  kernel: arch/sparc/boot/zImage is ready
Completed OK
# rm -rf /kisskb/build/powerpc-next_sparc64-defconfig_sparc64
# Build took: 0:00:41.630025