[PATCH 11/21] arm64: KVM: Implement the core world switch
Marc Zyngier
marc.zyngier at arm.com
Tue Nov 24 09:40:26 PST 2015
On Tue, 24 Nov 2015 17:29:14 +0000
Alex Bennée <alex.bennee at linaro.org> wrote:
>
> Marc Zyngier <marc.zyngier at arm.com> writes:
>
> > Implement the core of the world switch in C. Not everything is there
> > yet, and there is nothing to re-enter the world switch either.
> >
> > But this already outlines the code structure well enough.
> >
> > Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> > ---
> > arch/arm64/kvm/hyp/Makefile | 1 +
> > arch/arm64/kvm/hyp/switch.c | 134 ++++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 135 insertions(+)
> > create mode 100644 arch/arm64/kvm/hyp/switch.c
> >
> > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
> > index 1e1ff06..9c11b0f 100644
> > --- a/arch/arm64/kvm/hyp/Makefile
> > +++ b/arch/arm64/kvm/hyp/Makefile
> > @@ -8,3 +8,4 @@ obj-$(CONFIG_KVM_ARM_HOST) += timer-sr.o
> > obj-$(CONFIG_KVM_ARM_HOST) += sysreg-sr.o
> > obj-$(CONFIG_KVM_ARM_HOST) += debug-sr.o
> > obj-$(CONFIG_KVM_ARM_HOST) += entry.o
> > +obj-$(CONFIG_KVM_ARM_HOST) += switch.o
> > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> > new file mode 100644
> > index 0000000..a3af81a
> > --- /dev/null
> > +++ b/arch/arm64/kvm/hyp/switch.c
> > @@ -0,0 +1,134 @@
> > +/*
> > + * Copyright (C) 2015 - ARM Ltd
> > + * Author: Marc Zyngier <marc.zyngier at arm.com>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program. If not, see <http://www.gnu.org/licenses/>.
> > + */
> > +
> > +#include "hyp.h"
> > +
> > +static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
> > +{
> > + u64 val;
> > +
> > + /*
> > + * We are about to set CPTR_EL2.TFP to trap all floating point
> > + * register accesses to EL2, however, the ARM ARM clearly states that
> > + * traps are only taken to EL2 if the operation would not otherwise
> > + * trap to EL1. Therefore, always make sure that for 32-bit guests,
> > + * we set FPEXC.EN to prevent traps to EL1, when setting the TFP bit.
> > + */
> > + val = vcpu->arch.hcr_el2;
> > + if (val & HCR_RW) {
> > + write_sysreg(1 << 30, fpexc32_el2);
> > + isb();
> > + }
> > + write_sysreg(val, hcr_el2);
> > + write_sysreg(1 << 15, hstr_el2);
> > + write_sysreg(CPTR_EL2_TTA | CPTR_EL2_TFP, cptr_el2);
> > + write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
> > +}
> > +
> > +static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
> > +{
> > + write_sysreg(HCR_RW, hcr_el2);
> > + write_sysreg(0, hstr_el2);
> > + write_sysreg(read_sysreg(mdcr_el2) & MDCR_EL2_HPMN_MASK, mdcr_el2);
> > + write_sysreg(0, cptr_el2);
> > +}
> > +
> > +static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm *kvm = kern_hyp_va(vcpu->kvm);
> > + write_sysreg(kvm->arch.vttbr, vttbr_el2);
> > +}
> > +
> > +static void __hyp_text __deactivate_vm(struct kvm_vcpu *vcpu)
> > +{
> > + write_sysreg(0, vttbr_el2);
> > +}
> > +
> > +static hyp_alternate_select(__vgic_call_save_state,
> > + __vgic_v2_save_state, __vgic_v3_save_state,
> > + ARM64_HAS_SYSREG_GIC_CPUIF);
> > +
> > +static hyp_alternate_select(__vgic_call_restore_state,
> > + __vgic_v2_restore_state, __vgic_v3_restore_state,
> > + ARM64_HAS_SYSREG_GIC_CPUIF);
> > +
> > +static void __hyp_text __vgic_save_state(struct kvm_vcpu *vcpu)
> > +{
> > + __vgic_call_save_state()(vcpu);
> > + write_sysreg(read_sysreg(hcr_el2) & ~HCR_INT_OVERRIDE, hcr_el2);
> > +}
> > +
> > +static void __hyp_text __vgic_restore_state(struct kvm_vcpu *vcpu)
> > +{
> > + u64 val;
> > +
> > + val = read_sysreg(hcr_el2);
> > + val |= HCR_INT_OVERRIDE;
> > + val |= vcpu->arch.irq_lines;
> > + write_sysreg(val, hcr_el2);
> > +
> > + __vgic_call_restore_state()(vcpu);
> > +}
> > +
> > +int __hyp_text __guest_run(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_cpu_context *host_ctxt;
> > + struct kvm_cpu_context *guest_ctxt;
> > + u64 exit_code;
> > +
> > + vcpu = kern_hyp_va(vcpu);
> > + write_sysreg(vcpu, tpidr_el2);
> > +
> > + host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
> > + guest_ctxt = &vcpu->arch.ctxt;
> > +
> > + __sysreg_save_state(host_ctxt);
> > + __debug_cond_save_state(vcpu, &vcpu->arch.host_debug_state, host_ctxt);
> > +
> > + __activate_traps(vcpu);
> > + __activate_vm(vcpu);
> > +
> > + __vgic_restore_state(vcpu);
> > + __timer_restore_state(vcpu);
> > +
> > + /*
> > + * We must restore the 32-bit state before the sysregs, thanks
> > + * to Cortex-A57 erratum #852523.
> > + */
> > + __sysreg32_restore_state(vcpu);
> > + __sysreg_restore_state(guest_ctxt);
> > + __debug_restore_state(vcpu, &vcpu->arch.vcpu_debug_state,
> > guest_ctxt);
>
> Did you right this before guest debug was merged? Now
> vcpu.debug_ptr/VCPU_DEBUG_PTR selects which set of debug registers we
> are going to use before entering the guest.
I probably just overlooked that bit. Thanks for noticing it!
M.
--
Jazz is not dead. It just smells funny.
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