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KVM: arm/arm64: Move timer save/restore out of the hyp code

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As we are about to be lazy with saving and restoring the timer
registers, we prepare by moving all possible timer configuration logic
out of the hyp code.  All virtual timer registers can be programmed from
EL1 and since the arch timer is always a level triggered interrupt we
can safely do this with interrupts disabled in the host kernel on the
way to the guest without taking vtimer interrupts in the host kernel
(yet).

The downside is that the cntvoff register can only be programmed from
hyp mode, so we jump into hyp mode and back to program it.  This is also
safe, because the host kernel doesn't use the virtual timer in the KVM
code.  It may add a little performance performance penalty, but only
until following commits where we move this operation to vcpu load/put.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Christoffer Dall
2017-01-04 16:10:28 +01:00
committed by Christoffer Dall
parent f2a2129e0a
commit 688c50aa72
8 changed files with 95 additions and 52 deletions
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7
arch/arm/kvm/hyp/switch.c
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@@ -174,7 +174,7 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
__activate_vm(vcpu);
__vgic_restore_state(vcpu);
__timer_restore_state(vcpu);
__timer_enable_traps(vcpu);
__sysreg_restore_state(guest_ctxt);
__banked_restore_state(guest_ctxt);
@@ -191,7 +191,8 @@ again:
__banked_save_state(guest_ctxt);
__sysreg_save_state(guest_ctxt);
__timer_save_state(vcpu);
__timer_disable_traps(vcpu);
__vgic_save_state(vcpu);
__deactivate_traps(vcpu);
@@ -237,7 +238,7 @@ void __hyp_text __noreturn __hyp_panic(int cause)
vcpu = (struct kvm_vcpu *)read_sysreg(HTPIDR);
host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
__timer_save_state(vcpu);
__timer_disable_traps(vcpu);
__deactivate_traps(vcpu);
__deactivate_vm(vcpu);
__banked_restore_state(host_ctxt);