On 16/06/15 13:30, Vikram Sethi wrote: > On 06/16/15 01:46, Marc Zyngier wrote: >> On Tue, 16 Jun 2015 02:34:23 +0100 >> Vikram Sethi <vikrams@xxxxxxxxxxxxxx> wrote: >> >> Hi Vikram, >> >>> Hi Marc, Christoffer, Catalin, Will, >>> >>> I'm seeing an issue with KVM HCPTR (cp15) writes on guest entry/exit >>> on one of Qualcomm's CPU cores in AArch32 host and AArch32 guest >>> mode. Our CPU architects believe that HCPTR cp15 writes are context >>> changing and require an isb. With an isb in set_hcptr macro in >>> arch/arm/kvm/interrupts_head.S I am able to boot the Aarch32 guest, >>> but without it, I see strange crashes to hyp_undef or hyp_pabt. >> [...] >> >> Can you look at the following patch (queued for 4.2)? >> >> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/330955.html >> >> Please let me know if this solves the issue you are seeing. > Don't we have the same issue the first time guest touches FP and > traps i.e in switch_to_guest_vfp where we turn on floating point > access in HCPTR and immediately access FPEXC in store_vfp_state > without a isb? Good point, looks like my initial fix is incomplete. I'll repost a more complete fix but in the meantime, does adding the following work for you? diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S index 3ac7aca..5b30047 100644 --- a/arch/arm/kvm/interrupts.S +++ b/arch/arm/kvm/interrupts.S @@ -487,6 +487,7 @@ switch_to_guest_vfp: @ NEON/VFP used. Turn on VFP access. set_hcptr vmexit, (HCPTR_TCP(10) | HCPTR_TCP(11)) + isb @ Force execution of HCPTR as we've just reenabled VFP access @ Switch VFP/NEON hardware state to the guest's add r7, r0, #VCPU_VFP_HOST Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
