Buildresult: powerpc-fixes/mmu_defconfig/microblaze-gcc5 built on Nov 6, 17:37

kisskb

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Status:	OK
Date/Time:	Nov 6, 17:37
Duration:	0:00:48.889693
Builder:	ka7
Revision:	KVM: PPC: Book3S HV: Mask off LPCR_MER for a vCPU before running it to avoid spurious interrupts (`a373830f96db288a3eb43a8692b6bcd0bd88dfe1)`
Target:	powerpc-fixes/mmu_defconfig/microblaze-gcc5
Branch:	powerpc-fixes
Compiler:	microblaze-gcc5 (microblazeel-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.26.1)
Config:	mmu_defconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify a373830f96db288a3eb43a8692b6bcd0bd88dfe1^{commit} # git fetch -q -n -f https://github.com/linuxppc/linux fixes-test # git rev-parse -q --verify a373830f96db288a3eb43a8692b6bcd0bd88dfe1^{commit} a373830f96db288a3eb43a8692b6bcd0bd88dfe1 # git checkout -q -f -B kisskb a373830f96db288a3eb43a8692b6bcd0bd88dfe1 # git clean -qxdf # < git log -1 # commit a373830f96db288a3eb43a8692b6bcd0bd88dfe1 # Author: Gautam Menghani <gautam@linux.ibm.com> # Date: Mon Oct 28 14:34:09 2024 +0530 # # KVM: PPC: Book3S HV: Mask off LPCR_MER for a vCPU before running it to avoid spurious interrupts # # Running a L2 vCPU (see [1] for terminology) with LPCR_MER bit set and no # pending interrupts results in that L2 vCPU getting an infinite flood of # spurious interrupts. The 'if check' in kvmhv_run_single_vcpu() sets the # LPCR_MER bit if there are pending interrupts. # # The spurious flood problem can be observed in 2 cases: # 1. Crashing the guest while interrupt heavy workload is running # a. Start a L2 guest and run an interrupt heavy workload (eg: ipistorm) # b. While the workload is running, crash the guest (make sure kdump # is configured) # c. Any one of the vCPUs of the guest will start getting an infinite # flood of spurious interrupts. # # 2. Running LTP stress tests in multiple guests at the same time # a. Start 4 L2 guests. # b. Start running LTP stress tests on all 4 guests at same time. # c. In some time, any one/more of the vCPUs of any of the guests will # start getting an infinite flood of spurious interrupts. # # The root cause of both the above issues is the same: # 1. A NMI is sent to a running vCPU that has LPCR_MER bit set. # 2. In the NMI path, all registers are refreshed, i.e, H_GUEST_GET_STATE # is called for all the registers. # 3. When H_GUEST_GET_STATE is called for LPCR, the vcpu->arch.vcore->lpcr # of that vCPU at L1 level gets updated with LPCR_MER set to 1, and this # new value is always used whenever that vCPU runs, regardless of whether # there was a pending interrupt. # 4. Since LPCR_MER is set, the vCPU in L2 always jumps to the external # interrupt handler, and this cycle never ends. # # Fix the spurious flood by masking off the LPCR_MER bit before running a # L2 vCPU to ensure that it is not set if there are no pending interrupts. # # [1] Terminology: # 1. L0 : PAPR hypervisor running in HV mode # 2. L1 : Linux guest (logical partition) running on top of L0 # 3. L2 : KVM guest running on top of L1 # # Fixes: ec0f6639fa88 ("KVM: PPC: Book3S HV nestedv2: Ensure LPCR_MER bit is passed to the L0") # Cc: stable@vger.kernel.org # v6.8+ # Signed-off-by: Gautam Menghani <gautam@linux.ibm.com> # Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-gcc --version # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-ld --version # < git log --format=%s --max-count=1 a373830f96db288a3eb43a8692b6bcd0bd88dfe1 # make -s -j 32 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze-gcc5 CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- mmu_defconfig # < make -s -j 32 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze-gcc5 CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- help # make -s -j 32 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze-gcc5 CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- olddefconfig # make -s -j 32 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze-gcc5 CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- Kernel: arch/microblaze/boot/linux.bin is ready (#1) Completed OK # rm -rf /kisskb/build/powerpc-fixes_mmu_defconfig_microblaze-gcc5 # Build took: 0:00:48.889693

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