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 <th...@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 > >> _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
