Re: [RFC v2 1/6] xen/arm: Save and restore support with hvm context hypercalls

[Julien Grall <julien.grall@linaro.org>]

Hello Wei,


Thank you for the patch.

You are modifying common code in this patch. I've add Jan and Keir.

Also, I would create a separate patch for this code movement.

On 15/04/14 22:05, Wei Huang wrote:
> +
> +HVM_REGISTER_SAVE_RESTORE(GIC, hvm_gic_save_ctxt, hvm_gic_load_ctxt, 1,
> +                          HVMSR_PER_VCPU);

With new support for different GIC, I would differentiate VGIC and GIC 
save/restore.

Also can you append V2 in the name? GICv3 support will be added soon.

[..]

> +
>   /*
>    * Local variables:
>    * mode: C
> diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
> index 3d6a721..7c47eac 100644
> --- a/xen/arch/arm/vtimer.c
> +++ b/xen/arch/arm/vtimer.c
> @@ -21,6 +21,7 @@
>   #include <xen/lib.h>
>   #include <xen/timer.h>
>   #include <xen/sched.h>
> +#include <xen/hvm/save.h>
>   #include <asm/irq.h>
>   #include <asm/time.h>
>   #include <asm/gic.h>
> @@ -284,6 +285,76 @@ int vtimer_emulate(struct cpu_user_regs *regs, union hsr hsr)
>       }
>   }
>
> +static int hvm_vtimer_save_ctxt(struct domain *d, hvm_domain_context_t *h)
> +{
> +    struct hvm_hw_timer ctxt;
> +    struct vcpu *v;
> +    struct vtimer *t;
> +    int i, ret = 0;
> +
> +    /* Save the state of vtimer and ptimer */
> +    for_each_vcpu( d, v )
> +    {
> +        t = &v->arch.virt_timer;
> +        for ( i = 0; i < 2; i++ )
> +        {

Looping here is very confusing, what does mean 0? 1?

I would create an helper with the content of this loop and call twice 
this helper with the correct value in parameter.

Smth like:
     hvm_save_vtimer(TIMER_TYPE_PHYS, &v->arch.phys_timer);
     hvm_save_vtimer(TIMER_TYPE_VIRT, &v->arch.virt_timer);

> +            ctxt.cval = t->cval;
> +            ctxt.ctl = t->ctl;
> +            ctxt.vtb_offset = i ? d->arch.phys_timer_base.offset :
> +                d->arch.virt_timer_base.offset;
> +            ctxt.type = i ? TIMER_TYPE_PHYS : TIMER_TYPE_VIRT;
> +
> +            if ( (ret = hvm_save_entry(TIMER, v->vcpu_id, h, &ctxt)) != 0 )
> +                return ret;
> +
> +            t = &v->arch.phys_timer;

It will avoid this hackish line.

> +        }
> +    }
> +
> +    return ret;
> +}
> +
> +static int hvm_vtimer_load_ctxt(struct domain *d, hvm_domain_context_t *h)
> +{
> +    int vcpuid;
> +    struct hvm_hw_timer ctxt;
> +    struct vcpu *v;
> +    struct vtimer *t = NULL;
> +
> +    /* Which vcpu is this? */
> +    vcpuid = hvm_load_instance(h);
> +
> +    if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
> +    {
> +        dprintk(XENLOG_G_ERR, "HVM restore: dom%u has no vcpu%u\n",
> +                d->domain_id, vcpuid);
> +        return -EINVAL;
> +    }
> +
> +    if ( hvm_load_entry(TIMER, h, &ctxt) != 0 )
> +        return -EINVAL;
> +
> +    if ( ctxt.type == TIMER_TYPE_VIRT )
> +    {
> +        t = &v->arch.virt_timer;
> +        d->arch.virt_timer_base.offset = ctxt.vtb_offset;
> +    }
> +    else

else if ( ctx.type == TIMER_TYPE_PHYS ) ? Then fail if the ctx.type is 
wrong.

Even better I would use a switch case.

> +    {
> +        t = &v->arch.phys_timer;
> +        d->arch.phys_timer_base.offset = ctxt.vtb_offset;

Saving {virt,phys}_timer_base.offset which are per-domain seems a waste 
of space and confusing.

> +    }
> +
> +    t->cval = ctxt.cval;
> +    t->ctl = ctxt.ctl;
> +    t->v = v;
> +
> +    return 0;
> +}
> +

[..]

> diff --git a/xen/include/asm-arm/hvm/support.h b/xen/include/asm-arm/hvm/support.h
> new file mode 100644
> index 0000000..09f7cb8
> --- /dev/null
> +++ b/xen/include/asm-arm/hvm/support.h
> @@ -0,0 +1,29 @@
> +/*
> + * asm-arm/hvm/support.h: HVM support routines used by ARM.
> + *
> + * Copyright (c) 2014, Samsung Electronics.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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, write to the Free Software Foundation, Inc., 59 Temple
> + * Place - Suite 330, Boston, MA 02111-1307 USA.
> + */
> +
> +#ifndef __ASM_ARM_HVM_SUPPORT_H__
> +#define __ASM_ARM_HVM_SUPPORT_H__
> +
> +#include <xen/types.h>
> +#include <public/hvm/ioreq.h>
> +#include <xen/sched.h>
> +#include <xen/hvm/save.h>
> +#include <asm/processor.h>
> +
> +#endif /* __ASM_ARM_HVM_SUPPORT_H__ */
> diff --git a/xen/include/public/arch-arm/hvm/save.h b/xen/include/public/arch-arm/hvm/save.h
> index 75b8e65..f6ad258 100644
> --- a/xen/include/public/arch-arm/hvm/save.h
> +++ b/xen/include/public/arch-arm/hvm/save.h
> @@ -26,6 +26,136 @@
>   #ifndef __XEN_PUBLIC_HVM_SAVE_ARM_H__
>   #define __XEN_PUBLIC_HVM_SAVE_ARM_H__
>
> +#define HVM_FILE_MAGIC   0x92385520
> +#define HVM_FILE_VERSION 0x00000001
> +
> +struct hvm_save_header
> +{
> +    uint32_t magic;             /* Must be HVM_FILE_MAGIC */
> +    uint32_t version;           /* File format version */
> +    uint64_t changeset;         /* Version of Xen that saved this file */
> +    uint32_t cpuid;             /* MIDR_EL1 on the saving machine */
> +};
> +DECLARE_HVM_SAVE_TYPE(HEADER, 1, struct hvm_save_header);
> +
> +struct vgic_rank

I would rename into vgic_v2_rank.

> +{
> +    uint32_t ienable, iactive, ipend, pendsgi;
> +    uint32_t icfg[2];
> +    uint32_t ipriority[8];
> +    uint32_t itargets[8];
> +};
> +
> +struct hvm_hw_gic

I would rename into hvm_hw_vgic.

> +{
> +    uint32_t gic_hcr;
> +    uint32_t gic_vmcr;
> +    uint32_t gic_apr;
> +    uint32_t gic_lr[64];
> +    uint64_t event_mask;
> +    uint64_t lr_mask;
> +    struct vgic_rank ppi_state;

As said previously, I would separate GIC from VGIC save/restore.

-- 
Julien Grall