Re: [PATCH v10 08/11] xen: arch-specific hooks for domain_soft_reset()

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

On Tue, Jul 28, 2015 at 03:28:13PM +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 v9:
> - is_hvm_domain() -> has_hvm_container_domain() to support PVH [Jan Beulich]
> - introduce hvm_domain_soft_reset() to avoid making
>   hvm_destroy_all_ioreq_servers() public [Jan Beulich]
> - ASSERT( owner == d ) as we unconditionally do share_xen_page_with_guest()
>   on domain create path [Jan Beulich]
> - crash the domain when arch-specific hook fails [Jan Beulich]
> - eliminate mfn_new variable [Jan Beulich]
> - proper check for 'shared_info was never mapped' case.
> ---
>  xen/arch/arm/domain.c         |  5 +++
>  xen/arch/x86/domain.c         | 81 +++++++++++++++++++++++++++++++++++++++++++
>  xen/arch/x86/hvm/hvm.c        |  5 +++
>  xen/common/domain.c           |  7 ++++
>  xen/include/asm-x86/hvm/hvm.h |  1 +
>  xen/include/xen/domain.h      |  2 ++
>  6 files changed, 101 insertions(+)
> 
> 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 045f6ff..afc3e1e 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -710,6 +710,87 @@ 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, gfn;
> +    p2m_type_t p2mt;
> +    unsigned int i;
> +
> +    /* Soft reset is supported for HVM/PVH domains only. */
> +    if ( !has_hvm_container_domain(d) )
> +        return -EINVAL;
> +
> +    hvm_domain_soft_reset(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;
> +
> +    /*
> +     * The 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);
> +    ASSERT( owner == d );
> +
> +    mfn = page_to_mfn(page);
> +    gfn = mfn_to_gmfn(d, mfn);
> +
> +    /*
> +     * gfn == INVALID_GFN indicates that the shared_info page was never mapped
> +     * to the domain's address space and there is nothing to replace.
> +     */
> +    if ( gfn == INVALID_GFN )
> +        goto exit_put_page;
> +
> +    if ( mfn_x(get_gfn_query(d, gfn, &p2mt)) != 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;
> +    }
> +    guest_physmap_remove_page(d, gfn, mfn, PAGE_ORDER_4K);
> +
> +    ret = guest_physmap_add_page(d, gfn, page_to_mfn(new_page), 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 ec1d797..2bd7f0f 100644
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -6800,6 +6800,11 @@ bool_t altp2m_vcpu_emulate_ve(struct vcpu *v)
>      return 0;
>  }
>  
> +void hvm_domain_soft_reset(struct domain *d)
> +{
> +    hvm_destroy_all_ioreq_servers(d);
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/xen/common/domain.c b/xen/common/domain.c
> index 4c8e6a2..ffc8740 100644
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -1066,6 +1066,13 @@ int domain_soft_reset(struct domain *d)
>      for_each_vcpu ( d, v )
>          unmap_vcpu_info(v);
>  
> +    rc = arch_domain_soft_reset(d);
> +    if ( rc )
> +    {
> +        domain_crash(d);
> +        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 425327a..caeccf9 100644
> --- a/xen/include/asm-x86/hvm/hvm.h
> +++ b/xen/include/asm-x86/hvm/hvm.h
> @@ -226,6 +226,7 @@ extern const struct hvm_function_table *start_vmx(void);
>  int hvm_domain_initialise(struct domain *d);
>  void hvm_domain_relinquish_resources(struct domain *d);
>  void hvm_domain_destroy(struct domain *d);
> +void hvm_domain_soft_reset(struct domain *d);
>  
>  int hvm_vcpu_initialise(struct vcpu *v);
>  void hvm_vcpu_destroy(struct vcpu *v);
> 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
>