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[PATCH] KVM: Add Kconfig option to signal cross-endian guests

Started byThomas Huth <thuth@redhat.com>
First post2015-07-09 09:50 +0200
Last post2015-07-13 11:40 +0200
Articles 5 — 5 participants

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  [PATCH] KVM: Add Kconfig option to signal cross-endian guests Thomas Huth <thuth@redhat.com> - 2015-07-09 09:50 +0200
    Re: [PATCH] KVM: Add Kconfig option to signal cross-endian guests Cornelia Huck <cornelia.huck@de.ibm.com> - 2015-07-09 14:30 +0200
    Re: [PATCH] KVM: Add Kconfig option to signal cross-endian guests Paolo Bonzini <pbonzini@redhat.com> - 2015-07-09 15:00 +0200
      Re: [PATCH] KVM: Add Kconfig option to signal cross-endian guests "Michael S. Tsirkin" <mst@redhat.com> - 2015-07-09 15:10 +0200
    Re: [PATCH] KVM: Add Kconfig option to signal cross-endian guests Greg Kurz <gkurz@linux.vnet.ibm.com> - 2015-07-13 11:40 +0200

#1180493 — [PATCH] KVM: Add Kconfig option to signal cross-endian guests

FromThomas Huth <thuth@redhat.com>
Date2015-07-09 09:50 +0200
Subject[PATCH] KVM: Add Kconfig option to signal cross-endian guests
Message-ID<pKeKL-5N6-17@gated-at.bofh.it>
The option for supporting cross-endianness legacy guests in
the vhost and tun code should only be available on systems
that support cross-endian guests.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 arch/arm/kvm/Kconfig     | 1 +
 arch/arm64/kvm/Kconfig   | 1 +
 arch/powerpc/kvm/Kconfig | 1 +
 drivers/net/Kconfig      | 1 +
 drivers/vhost/Kconfig    | 1 +
 virt/kvm/Kconfig         | 3 +++
 6 files changed, 8 insertions(+)

diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
index bfb915d..9d8f363 100644
--- a/arch/arm/kvm/Kconfig
+++ b/arch/arm/kvm/Kconfig
@@ -31,6 +31,7 @@ config KVM
 	select KVM_VFIO
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_IRQFD
+	select KVM_CROSS_ENDIAN_GUESTS
 	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
 	---help---
 	  Support hosting virtualized guest machines.
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index bfffe8f..9af39fe 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -31,6 +31,7 @@ config KVM
 	select KVM_VFIO
 	select HAVE_KVM_EVENTFD
 	select HAVE_KVM_IRQFD
+	select KVM_CROSS_ENDIAN_GUESTS
 	---help---
 	  Support hosting virtualized guest machines.
 
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index 3caec2c..e028710 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -79,6 +79,7 @@ config KVM_BOOK3S_64_HV
 	select KVM_BOOK3S_HV_POSSIBLE
 	select MMU_NOTIFIER
 	select CMA
+	select KVM_CROSS_ENDIAN_GUESTS
 	---help---
 	  Support running unmodified book3s_64 guest kernels in
 	  virtual machines on POWER7 and PPC970 processors that have
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index c18f9e6..0c4ce47 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -261,6 +261,7 @@ config TUN
 config TUN_VNET_CROSS_LE
 	bool "Support for cross-endian vnet headers on little-endian kernels"
 	default n
+	depends on KVM_CROSS_ENDIAN_GUESTS
 	---help---
 	  This option allows TUN/TAP and MACVTAP device drivers in a
 	  little-endian kernel to parse vnet headers that come from a
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index 533eaf0..4d8ae6b 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -35,6 +35,7 @@ config VHOST
 
 config VHOST_CROSS_ENDIAN_LEGACY
 	bool "Cross-endian support for vhost"
+	depends on KVM_CROSS_ENDIAN_GUESTS
 	default n
 	---help---
 	  This option allows vhost to support guests with a different byte
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index e2c876d..cc7b28a 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -47,3 +47,6 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
 config KVM_COMPAT
        def_bool y
        depends on COMPAT && !S390
+
+config KVM_CROSS_ENDIAN_GUESTS
+       bool
-- 
1.8.3.1

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#1180671

FromCornelia Huck <cornelia.huck@de.ibm.com>
Date2015-07-09 14:30 +0200
Message-ID<pKj7I-6i-13@gated-at.bofh.it>
In reply to#1180493
On Thu,  9 Jul 2015 09:49:05 +0200
Thomas Huth <thuth@redhat.com> wrote:

> The option for supporting cross-endianness legacy guests in

s/cross-endianness/cross-endian/ ?

> the vhost and tun code should only be available on systems
> that support cross-endian guests.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  arch/arm/kvm/Kconfig     | 1 +
>  arch/arm64/kvm/Kconfig   | 1 +
>  arch/powerpc/kvm/Kconfig | 1 +
>  drivers/net/Kconfig      | 1 +
>  drivers/vhost/Kconfig    | 1 +
>  virt/kvm/Kconfig         | 3 +++
>  6 files changed, 8 insertions(+)

Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>

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#1180734

FromPaolo Bonzini <pbonzini@redhat.com>
Date2015-07-09 15:00 +0200
Message-ID<pKjAK-h5-17@gated-at.bofh.it>
In reply to#1180493

On 09/07/2015 11:48, Laurent Vivier wrote:
> 
> 
> On 09/07/2015 09:49, Thomas Huth wrote:
>> The option for supporting cross-endianness legacy guests in
>> the vhost and tun code should only be available on systems
>> that support cross-endian guests.
> 
> I'm sure I misunderstand something, but what happens if we use QEMU with
> TCG instead of KVM, i.e. a big endian powerpc kernel guest on x86_64
> little endian host ?

TCG does not yet support irqfd/ioeventfd, so it cannot be used with vhost.

Paolo

> Do you forbid the use of vhost in this case ?
> 
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  arch/arm/kvm/Kconfig     | 1 +
>>  arch/arm64/kvm/Kconfig   | 1 +
>>  arch/powerpc/kvm/Kconfig | 1 +
>>  drivers/net/Kconfig      | 1 +
>>  drivers/vhost/Kconfig    | 1 +
>>  virt/kvm/Kconfig         | 3 +++
>>  6 files changed, 8 insertions(+)
>>
>> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
>> index bfb915d..9d8f363 100644
>> --- a/arch/arm/kvm/Kconfig
>> +++ b/arch/arm/kvm/Kconfig
>> @@ -31,6 +31,7 @@ config KVM
>>  	select KVM_VFIO
>>  	select HAVE_KVM_EVENTFD
>>  	select HAVE_KVM_IRQFD
>> +	select KVM_CROSS_ENDIAN_GUESTS
>>  	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
>>  	---help---
>>  	  Support hosting virtualized guest machines.
>> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
>> index bfffe8f..9af39fe 100644
>> --- a/arch/arm64/kvm/Kconfig
>> +++ b/arch/arm64/kvm/Kconfig
>> @@ -31,6 +31,7 @@ config KVM
>>  	select KVM_VFIO
>>  	select HAVE_KVM_EVENTFD
>>  	select HAVE_KVM_IRQFD
>> +	select KVM_CROSS_ENDIAN_GUESTS
>>  	---help---
>>  	  Support hosting virtualized guest machines.
>>  
>> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
>> index 3caec2c..e028710 100644
>> --- a/arch/powerpc/kvm/Kconfig
>> +++ b/arch/powerpc/kvm/Kconfig
>> @@ -79,6 +79,7 @@ config KVM_BOOK3S_64_HV
>>  	select KVM_BOOK3S_HV_POSSIBLE
>>  	select MMU_NOTIFIER
>>  	select CMA
>> +	select KVM_CROSS_ENDIAN_GUESTS
>>  	---help---
>>  	  Support running unmodified book3s_64 guest kernels in
>>  	  virtual machines on POWER7 and PPC970 processors that have
>> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
>> index c18f9e6..0c4ce47 100644
>> --- a/drivers/net/Kconfig
>> +++ b/drivers/net/Kconfig
>> @@ -261,6 +261,7 @@ config TUN
>>  config TUN_VNET_CROSS_LE
>>  	bool "Support for cross-endian vnet headers on little-endian kernels"
>>  	default n
>> +	depends on KVM_CROSS_ENDIAN_GUESTS
>>  	---help---
>>  	  This option allows TUN/TAP and MACVTAP device drivers in a
>>  	  little-endian kernel to parse vnet headers that come from a
>> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
>> index 533eaf0..4d8ae6b 100644
>> --- a/drivers/vhost/Kconfig
>> +++ b/drivers/vhost/Kconfig
>> @@ -35,6 +35,7 @@ config VHOST
>>  
>>  config VHOST_CROSS_ENDIAN_LEGACY
>>  	bool "Cross-endian support for vhost"
>> +	depends on KVM_CROSS_ENDIAN_GUESTS
>>  	default n
>>  	---help---
>>  	  This option allows vhost to support guests with a different byte
>> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
>> index e2c876d..cc7b28a 100644
>> --- a/virt/kvm/Kconfig
>> +++ b/virt/kvm/Kconfig
>> @@ -47,3 +47,6 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
>>  config KVM_COMPAT
>>         def_bool y
>>         depends on COMPAT && !S390
>> +
>> +config KVM_CROSS_ENDIAN_GUESTS
>> +       bool
>>
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#1180738

From"Michael S. Tsirkin" <mst@redhat.com>
Date2015-07-09 15:10 +0200
Message-ID<pKjKq-Ae-17@gated-at.bofh.it>
In reply to#1180734
On Thu, Jul 09, 2015 at 02:57:33PM +0200, Paolo Bonzini wrote:
> 
> 
> On 09/07/2015 11:48, Laurent Vivier wrote:
> > 
> > 
> > On 09/07/2015 09:49, Thomas Huth wrote:
> >> The option for supporting cross-endianness legacy guests in
> >> the vhost and tun code should only be available on systems
> >> that support cross-endian guests.
> > 
> > I'm sure I misunderstand something, but what happens if we use QEMU with
> > TCG instead of KVM, i.e. a big endian powerpc kernel guest on x86_64
> > little endian host ?
> 
> TCG does not yet support irqfd/ioeventfd, so it cannot be used with vhost.
> 
> Paolo

vhost does not require irqfd anymore.  I think ioeventfd actually works
fine though I didn't try, it would be easy to support.


> > Do you forbid the use of vhost in this case ?
> > 
> >> Signed-off-by: Thomas Huth <thuth@redhat.com>
> >> ---
> >>  arch/arm/kvm/Kconfig     | 1 +
> >>  arch/arm64/kvm/Kconfig   | 1 +
> >>  arch/powerpc/kvm/Kconfig | 1 +
> >>  drivers/net/Kconfig      | 1 +
> >>  drivers/vhost/Kconfig    | 1 +
> >>  virt/kvm/Kconfig         | 3 +++
> >>  6 files changed, 8 insertions(+)
> >>
> >> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig
> >> index bfb915d..9d8f363 100644
> >> --- a/arch/arm/kvm/Kconfig
> >> +++ b/arch/arm/kvm/Kconfig
> >> @@ -31,6 +31,7 @@ config KVM
> >>  	select KVM_VFIO
> >>  	select HAVE_KVM_EVENTFD
> >>  	select HAVE_KVM_IRQFD
> >> +	select KVM_CROSS_ENDIAN_GUESTS
> >>  	depends on ARM_VIRT_EXT && ARM_LPAE && ARM_ARCH_TIMER
> >>  	---help---
> >>  	  Support hosting virtualized guest machines.
> >> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> >> index bfffe8f..9af39fe 100644
> >> --- a/arch/arm64/kvm/Kconfig
> >> +++ b/arch/arm64/kvm/Kconfig
> >> @@ -31,6 +31,7 @@ config KVM
> >>  	select KVM_VFIO
> >>  	select HAVE_KVM_EVENTFD
> >>  	select HAVE_KVM_IRQFD
> >> +	select KVM_CROSS_ENDIAN_GUESTS
> >>  	---help---
> >>  	  Support hosting virtualized guest machines.
> >>  
> >> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
> >> index 3caec2c..e028710 100644
> >> --- a/arch/powerpc/kvm/Kconfig
> >> +++ b/arch/powerpc/kvm/Kconfig
> >> @@ -79,6 +79,7 @@ config KVM_BOOK3S_64_HV
> >>  	select KVM_BOOK3S_HV_POSSIBLE
> >>  	select MMU_NOTIFIER
> >>  	select CMA
> >> +	select KVM_CROSS_ENDIAN_GUESTS
> >>  	---help---
> >>  	  Support running unmodified book3s_64 guest kernels in
> >>  	  virtual machines on POWER7 and PPC970 processors that have
> >> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> >> index c18f9e6..0c4ce47 100644
> >> --- a/drivers/net/Kconfig
> >> +++ b/drivers/net/Kconfig
> >> @@ -261,6 +261,7 @@ config TUN
> >>  config TUN_VNET_CROSS_LE
> >>  	bool "Support for cross-endian vnet headers on little-endian kernels"
> >>  	default n
> >> +	depends on KVM_CROSS_ENDIAN_GUESTS
> >>  	---help---
> >>  	  This option allows TUN/TAP and MACVTAP device drivers in a
> >>  	  little-endian kernel to parse vnet headers that come from a
> >> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
> >> index 533eaf0..4d8ae6b 100644
> >> --- a/drivers/vhost/Kconfig
> >> +++ b/drivers/vhost/Kconfig
> >> @@ -35,6 +35,7 @@ config VHOST
> >>  
> >>  config VHOST_CROSS_ENDIAN_LEGACY
> >>  	bool "Cross-endian support for vhost"
> >> +	depends on KVM_CROSS_ENDIAN_GUESTS
> >>  	default n
> >>  	---help---
> >>  	  This option allows vhost to support guests with a different byte
> >> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
> >> index e2c876d..cc7b28a 100644
> >> --- a/virt/kvm/Kconfig
> >> +++ b/virt/kvm/Kconfig
> >> @@ -47,3 +47,6 @@ config KVM_GENERIC_DIRTYLOG_READ_PROTECT
> >>  config KVM_COMPAT
> >>         def_bool y
> >>         depends on COMPAT && !S390
> >> +
> >> +config KVM_CROSS_ENDIAN_GUESTS
> >> +       bool
> >>
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#1182640

FromGreg Kurz <gkurz@linux.vnet.ibm.com>
Date2015-07-13 11:40 +0200
Message-ID<pLInp-3kU-11@gated-at.bofh.it>
In reply to#1180493
On Thu,  9 Jul 2015 09:49:05 +0200
Thomas Huth <thuth@redhat.com> wrote:

> The option for supporting cross-endianness legacy guests in
> the vhost and tun code should only be available on systems
> that support cross-endian guests.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Acked-by: Greg Kurz <gkurz@linux.vnet.ibm.com>

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