> Hi Emi, > > On Wed, Mar 26, 2025 at 02:14:35AM +0000, Emi Kisanuki (Fujitsu) wrote: > > Hi all, > > > > I tested Linux-cca cca-host/v7 patch with our Internal simulator based on > QEMU (with CCA and MPAM support). > > A panic occurred when starting Realm, but I don't think this is a problem with the > cca-host/v7 patch. > > The location of the panic is [1]. > > > > [1]https://lore.kernel.org/linux-arm-kernel/20241030160317.2528209-4-j > > oey.gouly@xxxxxxx diff --git a/arch/arm64/kernel/cpuinfo.c > > b/arch/arm64/kernel/cpuinfo.c index 44718d0482b3..46ba30d42b9b 100644 > > --- a/arch/arm64/kernel/cpuinfo.c > > +++ b/arch/arm64/kernel/cpuinfo.c > > @@ -478,6 +478,9 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 > *info) > > if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0)) > > __cpuinfo_store_cpu_32bit(&info->aarch32); > > > > + if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) > > + info->reg_mpamidr = read_cpuid(MPAMIDR_EL1); /////// > panic occurred here. > > + > > cpuinfo_detect_icache_policy(info); > > } > > > > There was no problem with the cca-host/v5 patch (based on v6.12). > > This panic is caused by accessing MPAMIDR_EL1 when the chip supports > MPAM. > > This functionality was enabled when the cca host patch base version was > rebased from v6.12 to v6.13. > > > > I am not familiar with TF-A, but I think this maybe a TF-A's bug. > > Because It seems TF-A sets MPAM3_EL3.TRAPLOWER to 0 during normal > guest boot in manage_extensions_nonsecure_per_world function[2]. > > However, TF-A does not set it to 0 during Realm guest boot in > manage_extensions_secure_per_world function. > > Therefore, a trap occurs against EL3 (TF-A), and it is likely being processed as > an invalid instruction (Undef). > > Your instinct is correct that this is *not* a kernel bug. It is the responsibility of the > RMM to provide a consistent feature set to the Realm. > > Looks like this was addressed recently in TF-RMM by hiding FEAT_MPAM: > > https://github.com/TF-RMM/tf-rmm/commit/7b0874403726d215c40054abfd5d > 8704049f8dac > > Thanks, > Oliver Hi Oliver Thank you. We will backport the patch you mentioned. I have verified the following 1. Launching the realm VM using Internal simulator → Successfully launched by disabling MPAM support in the ID register. 2. Running kvm-unit-tests (with lkvm) → All tests passed except for PMU (as expected, since PMU is not supported by the Internal simulator).[1] Tested-by: Emi Kisanuki <fj0570is@xxxxxxxxxxx> [1] https://gitlab.arm.com/linux-arm/kvm-unit-tests-cca cca/v3 Best Regards, Emi Kisanuki
