Re: [PATCH v9 08/11] xen: arch-specific hooks for domain_soft_reset()

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jul 16, 2015 at 06:27:23PM +0200, Vitaly Kuznetsov wrote:
> x86-specific hook cleans up the pirq-emuirq mappings, destroys all ioreq
> servers and and replaces the shared_info frame with an empty page to support
> subsequent XENMAPSPACE_shared_info call.
> 
> ARM-specific hook is -ENOSYS for now.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> Changes since v8:
> - Comments fixes [Konrad Rzeszutek Wilk]
> - pirq 0 is a valid pirq [Konrad Rzeszutek Wilk]
> - s/0/PAGE_ORDER_4K/ for guest_physmap_{add,remove}_page
>   [Konrad Rzeszutek Wilk]
> - Free new page in case of guest_physmap_add_page() failure
>   [Konrad Rzeszutek Wilk]
> - Make ARM-specific hook return -ENOSYS [Julien Grall]
> 
> Changes since 'PATCH RFC' of the 'reset everything' approach to PVHVM guest kexec:
> - Coding style, check get_gfn_query() return value, various minor fixes [Jan Beulich]
> - Do not unpause VCPUs on arch hook failure [Jan Beulich]
> ---
>  xen/arch/arm/domain.c         |  5 +++
>  xen/arch/x86/domain.c         | 84 +++++++++++++++++++++++++++++++++++++++++++
>  xen/arch/x86/hvm/hvm.c        |  2 +-
>  xen/common/domain.c           |  4 +++
>  xen/include/asm-x86/hvm/hvm.h |  2 ++
>  xen/include/xen/domain.h      |  2 ++
>  6 files changed, 98 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index b2bfc7d..5bdc2e9 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -655,6 +655,11 @@ void arch_domain_unpause(struct domain *d)
>  {
>  }
>  
> +int arch_domain_soft_reset(struct domain *d)
> +{
> +    return -ENOSYS;
> +}
> +
>  static int is_guest_pv32_psr(uint32_t psr)
>  {
>      switch (psr & PSR_MODE_MASK)
> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index 34ecd7c..1829535 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -704,6 +704,90 @@ void arch_domain_unpause(struct domain *d)
>          viridian_time_ref_count_thaw(d);
>  }
>  
> +int arch_domain_soft_reset(struct domain *d)
> +{
> +    struct page_info *page = virt_to_page(d->shared_info), *new_page;
> +    int ret = 0;
> +    struct domain *owner;
> +    unsigned long mfn, mfn_new, gfn;
> +    p2m_type_t p2mt;
> +    unsigned int i;
> +
> +    /* Soft reset is supported for HVM domains only. */
> +    if ( !is_hvm_domain(d) )
> +        return -EINVAL;
> +
> +    hvm_destroy_all_ioreq_servers(d);
> +
> +    spin_lock(&d->event_lock);
> +    for ( i = 0; i < d->nr_pirqs ; i++ )
> +    {
> +        if ( domain_pirq_to_emuirq(d, i) != IRQ_UNBOUND )
> +        {
> +            ret = unmap_domain_pirq_emuirq(d, i);
> +            if ( ret )
> +                break;
> +        }
> +    }
> +    spin_unlock(&d->event_lock);
> +
> +    if ( ret )
> +        return ret;
> +
> +    /*
> +     * shared_info page needs to be replaced with a new page, otherwise we
> +     * will get a hole if the domain does XENMAPSPACE_shared_info.
> +     */
> +
> +    owner = page_get_owner_and_reference(page);
> +    /* If shared_info page wasn't used, we do not need to replace it. */
> +    if ( owner != d )
> +        goto exit_put_page;
> +
> +    mfn = page_to_mfn(page);
> +    if ( !mfn_valid(mfn) )
> +    {
> +        printk(XENLOG_G_ERR "Dom%d's shared_info page points to invalid MFN\n",
> +               d->domain_id);
> +        ret = -EINVAL;
> +        goto exit_put_page;
> +    }
> +
> +    gfn = mfn_to_gmfn(d, mfn);
> +    if ( mfn_x(get_gfn_query(d, gfn, &p2mt)) == INVALID_MFN )
> +    {
> +        printk(XENLOG_G_ERR "Failed to get Dom%d's shared_info GFN (%lx)\n",
> +               d->domain_id, gfn);
> +        ret = -EINVAL;
> +        goto exit_put_page;
> +    }
> +
> +    new_page = alloc_domheap_page(d, 0);
> +    if ( !new_page )
> +    {
> +        printk(XENLOG_G_ERR "Failed to alloc a page to replace"
> +               " Dom%d's shared_info frame %lx\n", d->domain_id, gfn);
> +        ret = -ENOMEM;
> +        goto exit_put_gfn;
> +    }
> +    mfn_new = page_to_mfn(new_page);
> +    guest_physmap_remove_page(d, gfn, mfn, PAGE_ORDER_4K);
> +
> +    ret = guest_physmap_add_page(d, gfn, mfn_new, PAGE_ORDER_4K);
> +    if ( ret )
> +    {
> +        printk(XENLOG_G_ERR "Failed to add a page to replace"
> +               " Dom%d's shared_info frame %lx\n", d->domain_id, gfn);
> +        free_domheap_page(new_page);
> +    }
> + exit_put_gfn:
> +    put_gfn(d, gfn);
> + exit_put_page:
> +    put_page(page);
> +
> +    return ret;
> +}
> +
>  /*
>   * These are the masks of CR4 bits (subject to hardware availability) which a
>   * PV guest may not legitimiately attempt to modify.
> diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> index 545aa91..08a7a10 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -1370,7 +1370,7 @@ static void hvm_all_ioreq_servers_remove_vcpu(struct domain *d, struct vcpu *v)
>      spin_unlock(&d->arch.hvm_domain.ioreq_server.lock);
>  }
>  
> -static void hvm_destroy_all_ioreq_servers(struct domain *d)
> +void hvm_destroy_all_ioreq_servers(struct domain *d)
>  {
>      struct hvm_ioreq_server *s, *next;
>  
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 4f805d5..8401b42 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -1035,6 +1035,10 @@ int domain_soft_reset(struct domain *d)
>      for_each_vcpu ( d, v )
>          unmap_vcpu_info(v);
>  
> +    rc = arch_domain_soft_reset(d);
> +    if (rc)
> +        return rc;
> +
>      domain_resume(d);
>  
>      return 0;
> diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
> index 82f1b32..450ca0c 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -229,6 +229,8 @@ struct hvm_ioreq_server *hvm_select_ioreq_server(struct domain *d,
>  int hvm_send_ioreq(struct hvm_ioreq_server *s, ioreq_t *p, bool_t buffered);
>  unsigned int hvm_broadcast_ioreq(ioreq_t *p, bool_t buffered);
>  
> +void hvm_destroy_all_ioreq_servers(struct domain *d);
> +
>  void hvm_get_guest_pat(struct vcpu *v, u64 *guest_pat);
>  int hvm_set_guest_pat(struct vcpu *v, u64 guest_pat);
>  
> diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
> index 848db8a..a469fe0 100644
> --- a/xen/include/xen/domain.h
> +++ b/xen/include/xen/domain.h
> @@ -65,6 +65,8 @@ void arch_domain_shutdown(struct domain *d);
>  void arch_domain_pause(struct domain *d);
>  void arch_domain_unpause(struct domain *d);
>  
> +int arch_domain_soft_reset(struct domain *d);
> +
>  int arch_set_info_guest(struct vcpu *, vcpu_guest_context_u);
>  void arch_get_info_guest(struct vcpu *, vcpu_guest_context_u);
>  
> -- 
> 2.4.3
>