linux-dev/arch/powerpc/kernel/cpu_setup_power.c, branch linus/master

powerpc/64s: Always set PMU control registers to frozen/disabled when not in use

2021-11-24T10:08:57Z

KVM PMU management code looks for particular frozen/disabled bits in the PMU registers so it knows whether it must clear them when coming out of a guest or not. Setting this up helps KVM make these optimisations without getting confused. Longer term the better approach might be to move guest/host PMU switching to the perf subsystem. Signed-off-by: Nicholas Piggin Reviewed-by: Athira Jajeev Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211123095231.1036501-12-npiggin@gmail.com

powerpc/64s: Keep AMOR SPR a constant ~0 at runtime

2021-11-24T10:08:57Z

This register controls supervisor SPR modifications, and as such is only relevant for KVM. KVM always sets AMOR to ~0 on guest entry, and never restores it coming back out to the host, so it can be kept constant and avoid the mtSPR in KVM guest entry. Signed-off-by: Nicholas Piggin Reviewed-by: Fabiano Rosas Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211123095231.1036501-10-npiggin@gmail.com

powerpc/perf: MMCR0 control for PMU registers under PMCC=00

2020-12-03T14:01:29Z

PowerISA v3.1 introduces new control bit (PMCCEXT) for restricting access to group B PMU registers in problem state when MMCR0 PMCC=0b00. In problem state and when MMCR0 PMCC=0b00, setting the Monitor Mode Control Register bit 54 (MMCR0 PMCCEXT), will restrict read permission on Group B Performance Monitor Registers (SIER, SIAR, SDAR and MMCR1). When this bit is set to zero, group B registers will be readable. In other platforms (like power9), the older behaviour is retained where group B PMU SPRs are readable. Patch adds support for MMCR0 PMCCEXT bit in power10 by enabling this bit during boot and during the PMU event enable/disable callback functions. Signed-off-by: Athira Rajeev Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1606409684-1589-8-git-send-email-atrajeev@linux.vnet.ibm.com

powerpc/64s: Convert some cpu_setup() and cpu_restore() functions to C

2020-11-19T03:49:56Z

The only thing keeping the cpu_setup() and cpu_restore() functions used in the cputable entries for Power7, Power8, Power9 and Power10 in assembly was cpu_restore() being called before there was a stack in generic_secondary_smp_init(). Commit ("powerpc/64: Set up a kernel stack for secondaries before cpu_restore()") means that it is now possible to use C. Rewrite the functions in C so they are a little bit easier to read. This is not changing their functionality. Signed-off-by: Jordan Niethe [mpe: Tweak copyright and authorship notes] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201014072837.24539-2-jniethe5@gmail.com