Subject: [PATCH v3 18/19] KVM: ARM: vgic: add the GICv3 backend

From: [email-masked] (Christoffer Dall)
Date: Fri, 9 May 2014 16:07:31 +0200

On Wed, Apr 16, 2014 at 02:39:50PM +0100, Marc Zyngier wrote:
> Introduce the support code for emulating a GICv2 on top of GICv3
> hardware.
> 
> Acked-by: Catalin Marinas <[email-masked]>
> Signed-off-by: Marc Zyngier <[email-masked]>
> ---
>  include/kvm/arm_vgic.h |  26 ++++++
>  virt/kvm/arm/vgic-v3.c | 220 +++++++++++++++++++++++++++++++++++++++++++++++++
>  virt/kvm/arm/vgic.c    |   2 +
>  3 files changed, 248 insertions(+)
>  create mode 100644 virt/kvm/arm/vgic-v3.c
> 
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index c47dee5..6119a5a 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -32,6 +32,7 @@
>  #define VGIC_NR_SHARED_IRQS	(VGIC_NR_IRQS - VGIC_NR_PRIVATE_IRQS)
>  #define VGIC_MAX_CPUS		KVM_MAX_VCPUS
>  #define VGIC_MAX_LRS		(1 << 6)

shouldn't these have been renamed to VGIC_V2_MAX_LRS etc.?

> +#define VGIC_V3_MAX_LRS		16
>  
>  /* Sanity checks... */
>  #if (VGIC_MAX_CPUS > 8)
> @@ -71,6 +72,7 @@ struct kvm_vcpu;
>  
>  enum vgic_type {
>  	VGIC_V2,		/* Good ol' GICv2 */
> +	VGIC_V3,		/* v2 on v3, really */

comment maybe a bit too misleading, this is about the hardware, not what
we emulate.

>  };
>  
>  #define LR_STATE_PENDING	(1 << 0)
> @@ -169,6 +171,19 @@ struct vgic_v2_cpu_if {
>  	u32		vgic_lr[VGIC_MAX_LRS];
>  };
>  
> +struct vgic_v3_cpu_if {
> +#ifdef CONFIG_ARM_GIC_V3
> +	u32		vgic_hcr;
> +	u32		vgic_vmcr;
> +	u32		vgic_misr;	/* Saved only */
> +	u32		vgic_eisr;	/* Saved only */
> +	u32		vgic_elrsr;	/* Saved only */
> +	u32		vgic_ap0r[4];
> +	u32		vgic_ap1r[4];
> +	u64		vgic_lr[VGIC_V3_MAX_LRS];
> +#endif
> +};
> +
>  struct vgic_cpu {
>  #ifdef CONFIG_KVM_ARM_VGIC
>  	/* per IRQ to LR mapping */
> @@ -187,6 +202,7 @@ struct vgic_cpu {
>  	/* CPU vif control registers for world switch */
>  	union {
>  		struct vgic_v2_cpu_if	vgic_v2;
> +		struct vgic_v3_cpu_if	vgic_v3;
>  	};
>  #endif
>  };
> @@ -220,6 +236,16 @@ bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>  
>  int vgic_v2_probe(const struct vgic_ops **ops,
>  		  const struct vgic_params **params);
> +#ifdef CONFIG_ARM_GIC_V3
> +int vgic_v3_probe(const struct vgic_ops **ops,
> +		  const struct vgic_params **params);
> +#else
> +static inline int vgic_v3_probe(const struct vgic_ops **ops,
> +				const struct vgic_params **params)
> +{
> +	return -ENODEV;
> +}
> +#endif
>  
>  #else
>  static inline int kvm_vgic_hyp_init(void)
> diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
> new file mode 100644
> index 0000000..a804a73
> --- /dev/null
> +++ b/virt/kvm/arm/vgic-v3.c
> @@ -0,0 +1,220 @@
> +/*
> + * Copyright (C) 2013 ARM Limited, All Rights Reserved.
> + * Author: Marc Zyngier <[email-masked]>
> + *
> + * 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 <linux/cpu.h>
> +#include <linux/kvm.h>
> +#include <linux/kvm_host.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +
> +#include <linux/irqchip/arm-gic-v3.h>
> +
> +#include <asm/kvm_emulate.h>
> +#include <asm/kvm_arm.h>
> +#include <asm/kvm_mmu.h>
> +
> +/* These are for GICv2 emulation only */

Is this really true, seems like you're using them to form the lr values
for the hardware below.

> +#define GICH_LR_VIRTUALID		(0x3ffUL << 0)
> +#define GICH_LR_PHYSID_CPUID_SHIFT	(10)
> +#define GICH_LR_PHYSID_CPUID		(7UL << GICH_LR_PHYSID_CPUID_SHIFT)

can't we include them from the existing header file then?

> +
> +static u32 ich_vtr_el2;
> +
> +static struct vgic_lr vgic_v3_get_lr(const struct kvm_vcpu *vcpu, int lr)
> +{
> +	struct vgic_lr lr_desc;
> +	u64 val = vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[lr];
> +
> +	lr_desc.irq	= val & GICH_LR_VIRTUALID;
> +	lr_desc.source	= (val >> GICH_LR_PHYSID_CPUID_SHIFT) & 0xff;

isn't this mask only for bits [12:10] which would make it 0x7 ?

> +	lr_desc.state	= 0;
> +
> +	if (val & GICH_LR_PENDING_BIT)
> +		lr_desc.state |= LR_STATE_PENDING;
> +	if (val & GICH_LR_ACTIVE_BIT)
> +		lr_desc.state |= LR_STATE_ACTIVE;
> +	if (val & GICH_LR_EOI)
> +		lr_desc.state |= LR_EOI_INT;
> +
> +	return lr_desc;
> +}
> +
> +#define MK_LR_PEND(src, irq)	\
> +	(GICH_LR_PENDING_BIT | \
> +	 (((u32)(src)) << GICH_LR_PHYSID_CPUID_SHIFT) | (irq))
> +
> +static void vgic_v3_set_lr(struct kvm_vcpu *vcpu, int lr,
> +			   struct vgic_lr lr_desc)
> +{
> +	u64 lr_val = MK_LR_PEND(lr_desc.source, lr_desc.irq);
> +
> +	if (lr_desc.state & LR_STATE_PENDING)
> +		lr_val |= GICH_LR_PENDING_BIT;
> +	if (lr_desc.state & LR_STATE_ACTIVE)
> +		lr_val |= GICH_LR_ACTIVE_BIT;
> +	if (lr_desc.state & LR_EOI_INT)
> +		lr_val |= GICH_LR_EOI;
> +
> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_lr[lr] = lr_val;
> +
> +	/*
> +	 * Despite being EOIed, the LR may not have been marked as
> +	 * empty.
> +	 */
> +	if (!(lr_val & GICH_LR_STATE))
> +		vcpu->arch.vgic_cpu.vgic_v3.vgic_elrsr |= (1U << lr);
> +}

these funcitons are _identical_ to those in vgic_v2.  Seems like they
should share the code when emulating GICv2.

> +
> +static u64 vgic_v3_get_elrsr(const struct kvm_vcpu *vcpu)
> +{
> +	return vcpu->arch.vgic_cpu.vgic_v3.vgic_elrsr;
> +}
> +
> +static u64 vgic_v3_get_eisr(const struct kvm_vcpu *vcpu)
> +{
> +	return vcpu->arch.vgic_cpu.vgic_v3.vgic_eisr;
> +}
> +
> +static u32 vgic_v3_get_interrupt_status(const struct kvm_vcpu *vcpu)
> +{
> +	u32 misr = vcpu->arch.vgic_cpu.vgic_v3.vgic_misr;
> +	u32 ret = 0;
> +
> +	if (misr & GICH_MISR_EOI)
> +		ret |= INT_STATUS_EOI;
> +	if (misr & GICH_MISR_U)
> +		ret |= INT_STATUS_UNDERFLOW;
> +
> +	return ret;
> +}
> +
> +static void vgic_v3_get_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
> +{
> +	u32 vmcr = vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr;

vgic_v3?

> +
> +	vmcrp->ctlr = (vmcr & GICH_VMCR_CTLR_MASK) >> GICH_VMCR_CTLR_SHIFT;
> +	vmcrp->abpr = (vmcr & GICH_VMCR_BPR1_MASK) >> GICH_VMCR_BPR1_SHIFT;
> +	vmcrp->bpr  = (vmcr & GICH_VMCR_BPR0_MASK) >> GICH_VMCR_BPR0_SHIFT;
> +	vmcrp->pmr  = (vmcr & GICH_VMCR_PMR_MASK) >> GICH_VMCR_PMR_SHIFT;
> +}
> +
> +static void vgic_v3_clear_underflow(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_hcr &= ~GICH_HCR_UIE;
> +}
> +
> +static void vgic_v3_set_vmcr(struct kvm_vcpu *vcpu, struct vgic_vmcr *vmcrp)
> +{
> +	u32 vmcr;
> +
> +	vmcr  = (vmcrp->ctlr << GICH_VMCR_CTLR_SHIFT) & GICH_VMCR_CTLR_MASK;
> +	vmcr |= (vmcrp->abpr << GICH_VMCR_BPR1_SHIFT) & GICH_VMCR_BPR1_MASK;
> +	vmcr |= (vmcrp->bpr << GICH_VMCR_BPR0_SHIFT) & GICH_VMCR_BPR0_MASK;
> +	vmcr |= (vmcrp->pmr << GICH_VMCR_PMR_SHIFT) & GICH_VMCR_PMR_MASK;
> +
> +	vcpu->arch.vgic_cpu.vgic_v2.vgic_vmcr = vmcr;

vgic_v3?

> +}
> +
> +static void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
> +{
> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_hcr |= GICH_HCR_UIE;
> +}

can you group set/clear underflow please?

> +
> +static void vgic_v3_enable(struct kvm_vcpu *vcpu)
> +{
> +	/*
> +	 * By forcing VMCR to zero, the GIC will restore the binary
> +	 * points to their reset values. Anything else resets to zero
> +	 * anyway.
> +	 */
> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_vmcr = 0;
> +
> +	/* Get the show on the road... */
> +	vcpu->arch.vgic_cpu.vgic_v3.vgic_hcr = GICH_HCR_EN;
> +}
> +
> +static const struct vgic_ops vgic_v3_ops = {
> +	.get_lr			= vgic_v3_get_lr,
> +	.set_lr			= vgic_v3_set_lr,
> +	.get_elrsr		= vgic_v3_get_elrsr,
> +	.get_eisr		= vgic_v3_get_eisr,
> +	.get_interrupt_status	= vgic_v3_get_interrupt_status,
> +	.set_underflow		= vgic_v3_set_underflow,
> +	.clear_underflow	= vgic_v3_clear_underflow,
> +	.get_vmcr		= vgic_v3_get_vmcr,
> +	.set_vmcr		= vgic_v3_set_vmcr,
> +	.enable			= vgic_v3_enable,
> +};
> +
> +static struct vgic_params vgic_v3_params;
> +
> +int vgic_v3_probe(const struct vgic_ops **ops,
> +		  const struct vgic_params **params)
> +{
> +	int ret = 0;
> +	u32 gicv_idx;
> +	struct resource vcpu_res;
> +	struct device_node *vgic_node;
> +	struct vgic_params *vgic = &vgic_v3_params;
> +
> +	vgic_node = of_find_compatible_node(NULL, NULL, "arm,gic-v3");
> +	if (!vgic_node) {
> +		kvm_err("error: no compatible GICv3 node in DT\n");
> +		return -ENODEV;
> +	}
> +
> +	vgic->maint_irq = irq_of_parse_and_map(vgic_node, 0);
> +	if (!vgic->maint_irq) {
> +		kvm_err("error getting vgic maintenance irq from DT\n");
> +		ret = -ENXIO;
> +		goto out;
> +	}
> +
> +	ich_vtr_el2 = kvm_call_hyp(__vgic_v3_get_ich_vtr_el2);

I'm just going to assume this actually returns ich_vtr_el2 for the rest
of reviewing this patch and hope that I get to see this function in the
next patch ;)

> +
> +	/*
> +	 * The ListRegs field is 5 bits, but there is a architectural
> +	 * maximum of 16 list registers. Just ignore bit 4...
> +	 */
> +	vgic->nr_lr = (ich_vtr_el2 & 0xf) + 1;
> +
> +	if (of_property_read_u32(vgic_node, "#redistributor-regions", &gicv_idx))
> +		gicv_idx = 1;
> +
> +	gicv_idx += 3; /* Also skip GICD, GICC, GICH */
> +	if (of_address_to_resource(vgic_node, gicv_idx, &vcpu_res)) {
> +		kvm_err("Cannot obtain GICV region\n");
> +		ret = -ENXIO;
> +		goto out;
> +	}
> +	vgic->vcpu_base = vcpu_res.start;
> +	vgic->vctrl_base = (void *)(-1);

this indicates to me that all mentioning of vctrl_base should be local
to the vgic_v2 file?

> +	vgic->type = VGIC_V3;
> +
> +	kvm_info("%s@%llx IRQ%d\n", vgic_node->name,
> +		 vcpu_res.start, vgic->maint_irq);
> +
> +	*ops = &vgic_v3_ops;
> +	*params = vgic;
> +
> +out:
> +	of_node_put(vgic_node);
> +	return ret;
> +}
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 8365189..f29761b 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -1514,6 +1514,8 @@ int kvm_vgic_hyp_init(void)
>  
>  	ret = vgic_v2_probe(&vgic_ops, &vgic);
>  	if (ret)
> +		ret = vgic_v3_probe(&vgic_ops, &vgic);

this doesn't compile for me, missing Makefile include but even when
adding that, then other stuff breaks and the config option can actually
be set here... :(

> +	if (ret)
>  		return ret;
>  
>  	ret = request_percpu_irq(vgic->maint_irq, vgic_maintenance_handler,
> -- 
> 1.8.3.4
> 

Please fix the bisectability of this entire series.

I have reviewed the actual functional logic of this patch and have not
found any issues.

-Christoffer