[PATCH v4 39/40] KVM: arm/arm64: Move VGIC APR save/restore to vgic put/load
Christoffer Dall
christoffer.dall at linaro.org
Thu Feb 22 06:44:43 PST 2018
On Thu, Feb 22, 2018 at 01:11:55PM +0000, Marc Zyngier wrote:
> On 15/02/18 21:03, Christoffer Dall wrote:
> > The APRs can only have bits set when the guest acknowledges an interrupt
> > in the LR and can only have a bit cleared when the guest EOIs an
> > interrupt in the LR. Therefore, if we have no LRs with any
> > pending/active interrupts, the APR cannot change value and there is no
> > need to clear it on every exit from the VM (hint: it will have already
> > been cleared when we exited the guest the last time with the LRs all
> > EOIed).
> >
> > The only case we need to take care of is when we migrate the VCPU away
> > from a CPU or migrate a new VCPU onto a CPU, or when we return to
> > userspace to capture the state of the VCPU for migration. To make sure
> > this works, factor out the APR save/restore functionality into separate
> > functions called from the VCPU (and by extension VGIC) put/load hooks.
> >
> > Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
> > ---
> > arch/arm/include/asm/kvm_hyp.h | 2 +
> > arch/arm64/include/asm/kvm_hyp.h | 2 +
> > virt/kvm/arm/hyp/vgic-v3-sr.c | 124 +++++++++++++++++++++------------------
> > virt/kvm/arm/vgic/vgic-v2.c | 7 +--
> > virt/kvm/arm/vgic/vgic-v3.c | 5 ++
> > 5 files changed, 78 insertions(+), 62 deletions(-)
> >
> > diff --git a/arch/arm/include/asm/kvm_hyp.h b/arch/arm/include/asm/kvm_hyp.h
> > index 1ab8329e9ff7..530a3c1cfe6f 100644
> > --- a/arch/arm/include/asm/kvm_hyp.h
> > +++ b/arch/arm/include/asm/kvm_hyp.h
> > @@ -110,6 +110,8 @@ void __sysreg_restore_state(struct kvm_cpu_context *ctxt);
> >
> > void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
> > void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
> > +void __vgic_v3_save_aprs(struct kvm_vcpu *vcpu);
> > +void __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu);
> >
> > asmlinkage void __vfp_save_state(struct vfp_hard_struct *vfp);
> > asmlinkage void __vfp_restore_state(struct vfp_hard_struct *vfp);
> > diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
> > index febe417b8b4e..6f3929b2fcf7 100644
> > --- a/arch/arm64/include/asm/kvm_hyp.h
> > +++ b/arch/arm64/include/asm/kvm_hyp.h
> > @@ -124,6 +124,8 @@ int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu);
> >
> > void __vgic_v3_save_state(struct kvm_vcpu *vcpu);
> > void __vgic_v3_restore_state(struct kvm_vcpu *vcpu);
> > +void __vgic_v3_save_aprs(struct kvm_vcpu *vcpu);
> > +void __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu);
> > int __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu);
> >
> > void __timer_enable_traps(struct kvm_vcpu *vcpu);
> > diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
> > index 9abf2f3c12b5..437d7af08683 100644
> > --- a/virt/kvm/arm/hyp/vgic-v3-sr.c
> > +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
> > @@ -21,6 +21,7 @@
> >
> > #include <asm/kvm_emulate.h>
> > #include <asm/kvm_hyp.h>
> > +#include <asm/kvm_mmu.h>
> >
> > #define vtr_to_max_lr_idx(v) ((v) & 0xf)
> > #define vtr_to_nr_pre_bits(v) ((((u32)(v) >> 26) & 7) + 1)
> > @@ -221,14 +222,11 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
> >
> > if (used_lrs) {
> > int i;
> > - u32 nr_pre_bits;
> > u32 elrsr;
> >
> > elrsr = read_gicreg(ICH_ELSR_EL2);
> >
> > write_gicreg(0, ICH_HCR_EL2);
> > - val = read_gicreg(ICH_VTR_EL2);
> > - nr_pre_bits = vtr_to_nr_pre_bits(val);
> >
> > for (i = 0; i < used_lrs; i++) {
> > if (elrsr & (1 << i))
> > @@ -238,39 +236,10 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
> >
> > __gic_v3_set_lr(0, i);
> > }
> > -
> > - switch (nr_pre_bits) {
> > - case 7:
> > - cpu_if->vgic_ap0r[3] = __vgic_v3_read_ap0rn(3);
> > - cpu_if->vgic_ap0r[2] = __vgic_v3_read_ap0rn(2);
> > - case 6:
> > - cpu_if->vgic_ap0r[1] = __vgic_v3_read_ap0rn(1);
> > - default:
> > - cpu_if->vgic_ap0r[0] = __vgic_v3_read_ap0rn(0);
> > - }
> > -
> > - switch (nr_pre_bits) {
> > - case 7:
> > - cpu_if->vgic_ap1r[3] = __vgic_v3_read_ap1rn(3);
> > - cpu_if->vgic_ap1r[2] = __vgic_v3_read_ap1rn(2);
> > - case 6:
> > - cpu_if->vgic_ap1r[1] = __vgic_v3_read_ap1rn(1);
> > - default:
> > - cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
> > - }
> > } else {
> > if (static_branch_unlikely(&vgic_v3_cpuif_trap) ||
> > cpu_if->its_vpe.its_vm)
> > write_gicreg(0, ICH_HCR_EL2);
> > -
> > - cpu_if->vgic_ap0r[0] = 0;
> > - cpu_if->vgic_ap0r[1] = 0;
> > - cpu_if->vgic_ap0r[2] = 0;
> > - cpu_if->vgic_ap0r[3] = 0;
> > - cpu_if->vgic_ap1r[0] = 0;
> > - cpu_if->vgic_ap1r[1] = 0;
> > - cpu_if->vgic_ap1r[2] = 0;
> > - cpu_if->vgic_ap1r[3] = 0;
> > }
> >
> > val = read_gicreg(ICC_SRE_EL2);
> > @@ -287,8 +256,6 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
> > {
> > struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
> > u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
> > - u64 val;
> > - u32 nr_pre_bits;
> > int i;
> >
> > /*
> > @@ -306,32 +273,9 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
> > write_gicreg(cpu_if->vgic_vmcr, ICH_VMCR_EL2);
> > }
> >
> > - val = read_gicreg(ICH_VTR_EL2);
> > - nr_pre_bits = vtr_to_nr_pre_bits(val);
> > -
> > if (used_lrs) {
> > write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
> >
> > - switch (nr_pre_bits) {
> > - case 7:
> > - __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[3], 3);
> > - __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[2], 2);
> > - case 6:
> > - __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[1], 1);
> > - default:
> > - __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[0], 0);
> > - }
> > -
> > - switch (nr_pre_bits) {
> > - case 7:
> > - __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[3], 3);
> > - __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[2], 2);
> > - case 6:
> > - __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[1], 1);
> > - default:
> > - __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[0], 0);
> > - }
> > -
> > for (i = 0; i < used_lrs; i++)
> > __gic_v3_set_lr(cpu_if->vgic_lr[i], i);
> > } else {
> > @@ -364,6 +308,72 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
> > ICC_SRE_EL2);
> > }
> >
> > +void __hyp_text __vgic_v3_save_aprs(struct kvm_vcpu *vcpu)
> > +{
> > + struct vgic_v3_cpu_if *cpu_if;
> > + u64 val;
> > + u32 nr_pre_bits;
> > +
> > + vcpu = kern_hyp_va(vcpu);
> > + cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
> > +
> > + val = read_gicreg(ICH_VTR_EL2);
> > + nr_pre_bits = vtr_to_nr_pre_bits(val);
> > +
> > + switch (nr_pre_bits) {
> > + case 7:
> > + cpu_if->vgic_ap0r[3] = __vgic_v3_read_ap0rn(3);
> > + cpu_if->vgic_ap0r[2] = __vgic_v3_read_ap0rn(2);
> > + case 6:
> > + cpu_if->vgic_ap0r[1] = __vgic_v3_read_ap0rn(1);
> > + default:
> > + cpu_if->vgic_ap0r[0] = __vgic_v3_read_ap0rn(0);
> > + }
> > +
> > + switch (nr_pre_bits) {
> > + case 7:
> > + cpu_if->vgic_ap1r[3] = __vgic_v3_read_ap1rn(3);
> > + cpu_if->vgic_ap1r[2] = __vgic_v3_read_ap1rn(2);
> > + case 6:
> > + cpu_if->vgic_ap1r[1] = __vgic_v3_read_ap1rn(1);
> > + default:
> > + cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
> > + }
> > +}
> > +
> > +void __hyp_text __vgic_v3_restore_aprs(struct kvm_vcpu *vcpu)
> > +{
> > + struct vgic_v3_cpu_if *cpu_if;
> > + u64 val;
> > + u32 nr_pre_bits;
> > +
> > + vcpu = kern_hyp_va(vcpu);
> > + cpu_if = &vcpu->arch.vgic_cpu.vgic_v3;
> > +
> > + val = read_gicreg(ICH_VTR_EL2);
> > + nr_pre_bits = vtr_to_nr_pre_bits(val);
> > +
> > + switch (nr_pre_bits) {
> > + case 7:
> > + __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[3], 3);
> > + __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[2], 2);
> > + case 6:
> > + __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[1], 1);
> > + default:
> > + __vgic_v3_write_ap0rn(cpu_if->vgic_ap0r[0], 0);
> > + }
> > +
> > + switch (nr_pre_bits) {
> > + case 7:
> > + __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[3], 3);
> > + __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[2], 2);
> > + case 6:
> > + __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[1], 1);
> > + default:
> > + __vgic_v3_write_ap1rn(cpu_if->vgic_ap1r[0], 0);
> > + }
> > +}
> > +
> > void __hyp_text __vgic_v3_init_lrs(void)
> > {
> > int max_lr_idx = vtr_to_max_lr_idx(read_gicreg(ICH_VTR_EL2));
> > diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
> > index 1e5f3eb6973d..ca7cfee9f353 100644
> > --- a/virt/kvm/arm/vgic/vgic-v2.c
> > +++ b/virt/kvm/arm/vgic/vgic-v2.c
> > @@ -446,7 +446,6 @@ void vgic_v2_save_state(struct kvm_vcpu *vcpu)
> > {
> > struct kvm *kvm = vcpu->kvm;
> > struct vgic_dist *vgic = &kvm->arch.vgic;
> > - struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
> > void __iomem *base = vgic->vctrl_base;
> > u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
> >
> > @@ -454,11 +453,8 @@ void vgic_v2_save_state(struct kvm_vcpu *vcpu)
> > return;
> >
> > if (used_lrs) {
> > - cpu_if->vgic_apr = readl_relaxed(base + GICH_APR);
> > save_lrs(vcpu, base);
> > writel_relaxed(0, base + GICH_HCR);
> > - } else {
> > - cpu_if->vgic_apr = 0;
> > }
> > }
> >
> > @@ -476,7 +472,6 @@ void vgic_v2_restore_state(struct kvm_vcpu *vcpu)
> >
> > if (used_lrs) {
> > writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
> > - writel_relaxed(cpu_if->vgic_apr, base + GICH_APR);
> > for (i = 0; i < used_lrs; i++) {
> > writel_relaxed(cpu_if->vgic_lr[i],
> > base + GICH_LR0 + (i * 4));
> > @@ -490,6 +485,7 @@ void vgic_v2_load(struct kvm_vcpu *vcpu)
> > struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
> >
> > writel_relaxed(cpu_if->vgic_vmcr, vgic->vctrl_base + GICH_VMCR);
> > + writel_relaxed(cpu_if->vgic_apr, vgic->vctrl_base + GICH_APR);
> > }
> >
> > void vgic_v2_put(struct kvm_vcpu *vcpu)
> > @@ -498,4 +494,5 @@ void vgic_v2_put(struct kvm_vcpu *vcpu)
> > struct vgic_dist *vgic = &vcpu->kvm->arch.vgic;
> >
> > cpu_if->vgic_vmcr = readl_relaxed(vgic->vctrl_base + GICH_VMCR);
> > + cpu_if->vgic_apr = readl_relaxed(vgic->vctrl_base + GICH_APR);
> > }
> > diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> > index b76e21f3e6bd..4bafcd1e6bb8 100644
> > --- a/virt/kvm/arm/vgic/vgic-v3.c
> > +++ b/virt/kvm/arm/vgic/vgic-v3.c
> > @@ -16,6 +16,7 @@
> > #include <linux/kvm.h>
> > #include <linux/kvm_host.h>
> > #include <kvm/arm_vgic.h>
> > +#include <asm/kvm_hyp.h>
> > #include <asm/kvm_mmu.h>
> > #include <asm/kvm_asm.h>
> >
> > @@ -587,6 +588,8 @@ void vgic_v3_load(struct kvm_vcpu *vcpu)
> > */
> > if (likely(cpu_if->vgic_sre))
> > kvm_call_hyp(__vgic_v3_write_vmcr, cpu_if->vgic_vmcr);
> > +
> > + kvm_call_hyp(__vgic_v3_restore_aprs, vcpu);
> > }
> >
> > void vgic_v3_put(struct kvm_vcpu *vcpu)
> > @@ -595,4 +598,6 @@ void vgic_v3_put(struct kvm_vcpu *vcpu)
> >
> > if (likely(cpu_if->vgic_sre))
> > cpu_if->vgic_vmcr = kvm_call_hyp(__vgic_v3_read_vmcr);
> > +
> > + kvm_call_hyp(__vgic_v3_save_aprs, vcpu);
> > }
> >
>
> An unfortunate consequence of the save/restore de-aggregation process in
> this series is that we end-up doing quite a few EL2 calls in the !VHE
> case. We should probably think of consolidating those behind a single
> EL2 call if they have a measurable impact.
We could, but the trap to EL2 (without saving all GP regs beyond the
normal calling convention) is really cheap, so I don't think it *is*
that bad, but it *feels* bad. Also, few of these are in the criticial
path, right?
I'll admit that I haven't measured non-VHE GICv3 impact of this series
(only non-VHE GICv2 which saw a small improvement).
>
> In the meantime:
>
> Reviewed-by: Marc Zyngier <marc.zyngier at arm.com>
>
Thanks,
-Christoffer
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