Hi Mark, On 19.04.2022 13:22, Mark Brown wrote: > Now that basline support for the Scalable Matrix Extension (SME) is present > introduce the Kconfig option allowing it to be built. While the feature > registers don't impose a strong requirement for a system with SME to > support SVE at runtime the support for streaming mode SVE is mostly > shared with normal SVE so depend on SVE. > > Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> > Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> This patchset landed in linux next-20220426. By default SME is enabled and it breaks CPU hot-plug on all my arm64 test systems. Bisect points this patch, because it finally enables this feature. Here is a report from QEMU's arm64 virt machine: # for i in /sys/devices/system/cpu/cpu[1-9]; do echo 0 >$i/online; done psci: CPU1 killed (polled 0 ms) # cat /proc/cpuinfo | grep processor | wc -l 1 # for i in /sys/devices/system/cpu/cpu[1-9]; do echo 1 >$i/online; done ------------[ cut here ]------------ kernel BUG at arch/arm64/kernel/cpufeature.c:1353! Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in: bluetooth ecdh_generic ecc rfkill ipv6 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.18.0-rc3+ #4891 Hardware name: linux,dummy-virt (DT) pstate: 200001c5 (nzCv dAIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : __read_sysreg_by_encoding+0x350/0x354 lr : has_cpuid_feature+0x6c/0xe0 ... Call trace: __read_sysreg_by_encoding+0x350/0x354 has_cpuid_feature+0x6c/0xe0 verify_local_cpu_caps+0x98/0x130 check_local_cpu_capabilities+0x2c/0x270 secondary_start_kernel+0xc0/0x170 __secondary_switched+0xa0/0xa4 Code: d53802d3 17ffff49 d5380233 17ffff47 (d4210000) ---[ end trace 0000000000000000 ]--- Kernel panic - not syncing: Attempted to kill the idle task! SMP: stopping secondary CPUs Kernel Offset: 0x4e81fb600000 from 0xffff800008000000 PHYS_OFFSET: 0xffff98f240000000 CPU features: 0x440,00033c08,00001086 Memory Limit: none ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- Disabling SME on top of next-20220426 hides this issue. > --- > arch/arm64/Kconfig | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 57c4c995965f..0897984918e8 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -1939,6 +1939,17 @@ config ARM64_SVE > booting the kernel. If unsure and you are not observing these > symptoms, you should assume that it is safe to say Y. > > +config ARM64_SME > + bool "ARM Scalable Matrix Extension support" > + default y > + depends on ARM64_SVE > + help > + The Scalable Matrix Extension (SME) is an extension to the AArch64 > + execution state which utilises a substantial subset of the SVE > + instruction set, together with the addition of new architectural > + register state capable of holding two dimensional matrix tiles to > + enable various matrix operations. > + > config ARM64_MODULE_PLTS > bool "Use PLTs to allow module memory to spill over into vmalloc area" > depends on MODULES Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
