| Message ID | 20241015133923.3910916-1-joey.gouly@arm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: arm64: Hide unsupported MPAM from the guest | expand |
> -----Original Message----- > From: Joey Gouly <joey.gouly@arm.com> > Sent: Tuesday, October 15, 2024 2:39 PM > To: linux-arm-kernel@lists.infradead.org; kvmarm@lists.linux.dev > Cc: anshuman.khandual@arm.com; james.morse@arm.com; > joey.gouly@arm.com; Marc Zyngier <maz@kernel.org>; Oliver Upton > <oliver.upton@linux.dev>; Suzuki K Poulose <suzuki.poulose@arm.com>; > yuzenghui <yuzenghui@huawei.com>; Jing Zhang > <jingzhangos@google.com>; Shameerali Kolothum Thodi > <shameerali.kolothum.thodi@huawei.com>; Catalin Marinas > <catalin.marinas@arm.com>; Will Deacon <will@kernel.org> > Subject: [PATCH v5 0/7] KVM: arm64: Hide unsupported MPAM from the > guest I did basic sanity tests with this series on a HiSilicon platform that has MPAM support and it looks fine. FWIW, Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> Thanks, SHameer
Hi, Thanks Gavin and Marc for the feedback, hopefully incorporated it all here. changes since v4 [1]: - Swap order of patches, to be able to use MPAMIDR_EL1_HAS_HCR_SHIFT from el2_setup.h - Remove trap_mpam() and use undef_acccess() directly - Stopped using ID_FILTERED() for the 32-bit ID register - Fix ID_AA64PFR1_EL1 sanitisation - Fix MPAM_EL1 encoding - Fix bug that set everything apart from MPAM_frac as writable in ID_AA64PFR1_EL1. Match the current behaviour, so nothing is writable. James wrote: This series fixes up a long standing bug where MPAM was accidentally exposed to a guest, but the feature was not otherwise trapped or context switched. This could result in KVM warning about unexpected traps, and injecting an undef into the guest contradicting the ID registers. This would prevent an MPAM aware kernel from booting - fortunately, there aren't any of those. Ideally, we'd take the MPAM feature away from the ID registers, but that would leave existing guests unable to migrate to a newer kernel. Instead, just ignore that field when it matches the hardware. KVM wasn't going to expose MPAM anyway. The guest will not see MPAM in the id registers. This series includes the head.S and KVM changes to enable/disable traps. If MPAM is neither enabled nor emulated by EL3 firmware, these system register accesses will trap to EL3. If your kernel doesn't boot, and the problem bisects here - please update your firmware. MPAM has been supported by trusted firmware since v1.6 in 2018. (also noted on patch 3). Thanks, Joey [1] https://lore.kernel.org/linux-arm-kernel/20241004110714.2051604-1-joey.gouly@arm.com/ James Morse (7): arm64/sysreg: Convert existing MPAM sysregs and add the remaining entries arm64: head.S: Initialise MPAM EL2 registers and disable traps arm64: cpufeature: discover CPU support for MPAM KVM: arm64: Fix missing traps of guest accesses to the MPAM registers KVM: arm64: Add a macro for creating filtered sys_reg_descs entries KVM: arm64: Disable MPAM visibility by default and ignore VMM writes KVM: arm64: selftests: Test ID_AA64PFR0.MPAM isn't completely ignored .../arch/arm64/cpu-feature-registers.rst | 2 + arch/arm64/Kconfig | 20 +++ arch/arm64/include/asm/cpu.h | 1 + arch/arm64/include/asm/cpucaps.h | 2 + arch/arm64/include/asm/cpufeature.h | 12 ++ arch/arm64/include/asm/el2_setup.h | 16 ++ arch/arm64/include/asm/kvm_arm.h | 1 + arch/arm64/include/asm/mpam.h | 32 ++++ arch/arm64/include/asm/sysreg.h | 12 -- arch/arm64/kernel/Makefile | 2 + arch/arm64/kernel/cpufeature.c | 97 +++++++++++ arch/arm64/kernel/cpuinfo.c | 4 + arch/arm64/kernel/image-vars.h | 5 + arch/arm64/kernel/mpam.c | 6 + arch/arm64/kvm/hyp/include/hyp/switch.h | 32 ++++ arch/arm64/kvm/sys_regs.c | 105 +++++++++--- arch/arm64/tools/cpucaps | 1 + arch/arm64/tools/sysreg | 161 ++++++++++++++++++ .../selftests/kvm/aarch64/set_id_regs.c | 100 ++++++++++- 19 files changed, 571 insertions(+), 40 deletions(-) create mode 100644 arch/arm64/include/asm/mpam.h create mode 100644 arch/arm64/kernel/mpam.c