From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Vivier Subject: Re: [PATCH] KVM: Add Kconfig option to signal cross-endian guests Date: Thu, 09 Jul 2015 11:48:14 +0200 Message-ID: <559E435E.9050608@redhat.com> References: <20150707195012-mutt-send-email-mst@redhat.com> <1436428145-29823-1-git-send-email-thuth@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: linux-arm-kernel@lists.infradead.org, Gleb Natapov , Paolo Bonzini , Christoffer Dall , Marc Zyngier , Alexander Graf , Paul Mackerras , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kraxel@redhat.com, Cornelia Huck , Linus Torvalds To: Thomas Huth , "Michael S. Tsirkin" , kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, kvm-ppc@vger.kernel.org, virtualization@lists.linux-foundation.org, Greg Kurz Return-path: In-Reply-To: <1436428145-29823-1-git-send-email-thuth@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 ? Do you forbid the use of vhost in this case ? > Signed-off-by: Thomas Huth > --- > 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 >