[PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

[PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

[Juergen Gross]

Booting a Xen PVH guest requires a special boot entry as it is
mandatory to setup some Xen-specific interfaces rather early. When grub
or OVMF are used as boot loaders, however, those will fill the boot
parameters in zeropage and there is no longer a need to do something
PVH specific in the early boot path.

This patch series adds support for that scenario by identifying PVH
environment and doing the required init steps via Xen hooks instead of
using a dedicated boot entry.

The dedicated entry is still needed for support of Dom0 running in PVH
mode as in this case there is no grub or OVMF involved for filling in
the boot parameters.

Juergen Gross (3):
  x86/acpi: add test for ACPI_FADT_NO_VGA
  x86: add guest_late_init hook to hypervisor_x86 structure
  x86/xen: use guest_late_init to detect Xen PVH guest

 arch/x86/include/asm/hypervisor.h | 11 +++++++++++
 arch/x86/include/asm/kvm_para.h   |  2 --
 arch/x86/include/asm/x86_init.h   |  1 +
 arch/x86/kernel/acpi/boot.c       |  5 +++++
 arch/x86/kernel/kvm.c             |  3 ++-
 arch/x86/kernel/setup.c           |  2 +-
 arch/x86/xen/enlighten_hvm.c      | 24 ++++++++++++++++++++++--
 arch/x86/xen/enlighten_pvh.c      |  9 ---------
 8 files changed, 42 insertions(+), 15 deletions(-)

-- 
2.12.3


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Re: [PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

[Boris Ostrovsky]

On 11/08/2017 08:40 AM, Juergen Gross wrote:
> On 08/11/17 14:37, Boris Ostrovsky wrote:
>> On 11/08/2017 04:07 AM, Juergen Gross wrote:
>>> Booting a Xen PVH guest requires a special boot entry as it is
>>> mandatory to setup some Xen-specific interfaces rather early. When grub
>>> or OVMF are used as boot loaders, however, those will fill the boot
>>> parameters in zeropage and there is no longer a need to do something
>>> PVH specific in the early boot path.
>>>
>>> This patch series adds support for that scenario by identifying PVH
>>> environment and doing the required init steps via Xen hooks instead of
>>> using a dedicated boot entry.
>>>
>>> The dedicated entry is still needed for support of Dom0 running in PVH
>>> mode as in this case there is no grub or OVMF involved for filling in
>>> the boot parameters.
>> We are going to continue supporting direct boot of unprivileged guests
>> too so this entry point will be needed not for dom0 only.
> Sure, but using e.g. grub in this case would be an alternative. For Dom0
> this alternative isn't existing. So this entry is mandatory, not a "nice
> to have".

Right, I was just pointing out that the way the message is phrased makes
it sounds (to me at least) as if dom0 is the only reason for the
dedicated entry point.

-boris

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Re: [PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

[Juergen Gross]

On 08/11/17 14:37, Boris Ostrovsky wrote:
> On 11/08/2017 04:07 AM, Juergen Gross wrote:
>> Booting a Xen PVH guest requires a special boot entry as it is
>> mandatory to setup some Xen-specific interfaces rather early. When grub
>> or OVMF are used as boot loaders, however, those will fill the boot
>> parameters in zeropage and there is no longer a need to do something
>> PVH specific in the early boot path.
>>
>> This patch series adds support for that scenario by identifying PVH
>> environment and doing the required init steps via Xen hooks instead of
>> using a dedicated boot entry.
>>
>> The dedicated entry is still needed for support of Dom0 running in PVH
>> mode as in this case there is no grub or OVMF involved for filling in
>> the boot parameters.
> 
> We are going to continue supporting direct boot of unprivileged guests
> too so this entry point will be needed not for dom0 only.

Sure, but using e.g. grub in this case would be an alternative. For Dom0
this alternative isn't existing. So this entry is mandatory, not a "nice
to have".


Juergen


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Re: [PATCH 0/3] x86/xen: support booting PVH guest via standard boot path

[Boris Ostrovsky]

On 11/08/2017 04:07 AM, Juergen Gross wrote:
> Booting a Xen PVH guest requires a special boot entry as it is
> mandatory to setup some Xen-specific interfaces rather early. When grub
> or OVMF are used as boot loaders, however, those will fill the boot
> parameters in zeropage and there is no longer a need to do something
> PVH specific in the early boot path.
>
> This patch series adds support for that scenario by identifying PVH
> environment and doing the required init steps via Xen hooks instead of
> using a dedicated boot entry.
>
> The dedicated entry is still needed for support of Dom0 running in PVH
> mode as in this case there is no grub or OVMF involved for filling in
> the boot parameters.

We are going to continue supporting direct boot of unprivileged guests
too so this entry point will be needed not for dom0 only.

-boris

>
> Juergen Gross (3):
>   x86/acpi: add test for ACPI_FADT_NO_VGA
>   x86: add guest_late_init hook to hypervisor_x86 structure
>   x86/xen: use guest_late_init to detect Xen PVH guest
>
>  arch/x86/include/asm/hypervisor.h | 11 +++++++++++
>  arch/x86/include/asm/kvm_para.h   |  2 --
>  arch/x86/include/asm/x86_init.h   |  1 +
>  arch/x86/kernel/acpi/boot.c       |  5 +++++
>  arch/x86/kernel/kvm.c             |  3 ++-
>  arch/x86/kernel/setup.c           |  2 +-
>  arch/x86/xen/enlighten_hvm.c      | 24 ++++++++++++++++++++++--
>  arch/x86/xen/enlighten_pvh.c      |  9 ---------
>  8 files changed, 42 insertions(+), 15 deletions(-)
>


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