Re: [Xen-devel] [PATCH v11 09/12] xen/pvh: Piggyback on PVHVM XenBus and event channels for PVH.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 17 Dec 2013, Konrad Rzeszutek Wilk wrote:
> From: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> 
> PVH is a PV guest with a twist - there are certain things
> that work in it like HVM and some like PV. There is
> a similar mode - PVHVM where we run in HVM mode with
> PV code enabled - and this patch explores that.
> 
> The most notable PV interfaces are the XenBus and event channels.
> For PVH, we will use XenBus and event channels.
> 
> For the XenBus mechanism we piggyback on how it is done for
> PVHVM guests.
> 
> Ditto for the event channel mechanism - we piggyback on PVHVM -
> by setting up a specific vector callback and that
> vector ends up calling the event channel mechanism to
> dispatch the events as needed.
> 
> This means that from a pvops perspective, we can use
> native_irq_ops instead of the Xen PV specific. Albeit in the
> future we could support pirq_eoi_map. But that is
> a feature request that can be shared with PVHVM.
> 
> Signed-off-by: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  arch/x86/xen/enlighten.c           | 6 ++++++
>  arch/x86/xen/irq.c                 | 5 ++++-
>  drivers/xen/events.c               | 5 +++++
>  drivers/xen/xenbus/xenbus_client.c | 3 ++-
>  4 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index e420613..7fceb51 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1134,6 +1134,8 @@ void xen_setup_shared_info(void)
>       /* In UP this is as good a place as any to set up shared info */
>       xen_setup_vcpu_info_placement();
>  #endif
> +     if (xen_pvh_domain())
> +             return;
>  
>       xen_setup_mfn_list_list();
>  }

This is another one of those cases where I think we would benefit from
introducing xen_setup_shared_info_pvh instead of adding more ifs here.


> @@ -1146,6 +1148,10 @@ void xen_setup_vcpu_info_placement(void)
>       for_each_possible_cpu(cpu)
>               xen_vcpu_setup(cpu);
>  
> +     /* PVH always uses native IRQ ops */
> +     if (xen_pvh_domain())
> +             return;
> +
>       /* xen_vcpu_setup managed to place the vcpu_info within the
>          percpu area for all cpus, so make use of it */
>       if (have_vcpu_info_placement) {

Same here?


> diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
> index 0da7f86..4f7f351 100644
> --- a/arch/x86/xen/irq.c
> +++ b/arch/x86/xen/irq.c
> @@ -5,6 +5,7 @@
>  #include <xen/interface/xen.h>
>  #include <xen/interface/sched.h>
>  #include <xen/interface/vcpu.h>
> +#include <xen/features.h>
>  #include <xen/events.h>
>  
>  #include <asm/xen/hypercall.h>
> @@ -128,6 +129,8 @@ static const struct pv_irq_ops xen_irq_ops __initconst = {
>  
>  void __init xen_init_irq_ops(void)
>  {
> -     pv_irq_ops = xen_irq_ops;
> +     /* For PVH we use default pv_irq_ops settings */
> +     if (!xen_feature(XENFEAT_hvm_callback_vector))
> +             pv_irq_ops = xen_irq_ops;
>       x86_init.irqs.intr_init = xen_init_IRQ;
>  }
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 4035e83..627a16a 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -1922,6 +1922,11 @@ void __init xen_init_IRQ(void)
>               if (xen_initial_domain())
>                       pci_xen_initial_domain();
>  
> +             if (xen_feature(XENFEAT_hvm_callback_vector)) {
> +                     xen_callback_vector();
> +                     return;
> +             }

There is another call to xen_callback_vector in the if
(xen_hvm_domain()) path. Could we just move it out and have a single one
if (xen_feature(XENFEAT_hvm_callback_vector))?


>               pirq_eoi_map = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
>               eoi_gmfn.gmfn = virt_to_mfn(pirq_eoi_map);
>               rc = HYPERVISOR_physdev_op(PHYSDEVOP_pirq_eoi_gmfn_v2, 
> &eoi_gmfn);
> diff --git a/drivers/xen/xenbus/xenbus_client.c 
> b/drivers/xen/xenbus/xenbus_client.c
> index ec097d6..7f7c454 100644
> --- a/drivers/xen/xenbus/xenbus_client.c
> +++ b/drivers/xen/xenbus/xenbus_client.c
> @@ -45,6 +45,7 @@
>  #include <xen/grant_table.h>
>  #include <xen/xenbus.h>
>  #include <xen/xen.h>
> +#include <xen/features.h>
>  
>  #include "xenbus_probe.h"
>  
> @@ -743,7 +744,7 @@ static const struct xenbus_ring_ops ring_ops_hvm = {
>  
>  void __init xenbus_ring_ops_init(void)
>  {
> -     if (xen_pv_domain())
> +     if (xen_pv_domain() && !xen_feature(XENFEAT_auto_translated_physmap))

Can we just change this test to

if (!xen_feature(XENFEAT_auto_translated_physmap))

?


>               ring_ops = &ring_ops_pv;
>       else
>               ring_ops = &ring_ops_hvm;
> -- 
> 1.8.3.1
> 
> 
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> 

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