Messages in this thread | | | From | Sebastian Ott <> | Subject | [PATCH 0/4] KVM: arm64: emulation for CTR_EL0 | Date | Fri, 5 Apr 2024 14:01:04 +0200 |
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Hej folks,
I'm looking into supporting migration between 2 Ampere Altra (Max) machines (using Neoverse-N1). They are almost identical regarding their feature id register state except for CTR_EL0.DIC which is set on one machine but not the other.
CTR_EL0 is currently marked as invariant and migrating a VM between those 2 machines using qemu fails.
I've send this out as an RFC before [0]. What I've changed here based on feedback I've got from Marc was: * store the emulated value per VM and not per VCPU * allow to change more values than just the DIC bit * only trap guest access to that reg when needed * make sure to not present the guest with an inconsistent register set
Patch 2 adds a ctr_el0 member to struct kvm_arch - would it be preferred to add it into kvm->arch.id_regs[] (this would mean to increase that array 4x)?
Patch 3 resets CLIDR_EL1 after a write to CTR_EL0 potentially changing the value for CLIDR_EL1 - would that be ok for userspace?
Thanks, Sebastian
[0]: https://lore.kernel.org/all/20240318111636.10613-1-sebott@redhat.com/T/
Sebastian Ott (4): KVM: arm64: change return value in arm64_check_features() KVM: arm64: maintain per VM value for CTR_EL0 KVM: arm64: add emulation for CTR_EL0 register KVM: arm64: show writable masks for feature registers
arch/arm64/include/asm/kvm_host.h | 1 + arch/arm64/kvm/sys_regs.c | 131 ++++++++++++++++++++---------- 2 files changed, 89 insertions(+), 43 deletions(-)
-- 2.42.0
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