From mboxrd@z Thu Jan 1 00:00:00 1970 From: mst@redhat.com (Michael S. Tsirkin) Date: Mon, 14 Oct 2013 13:46:04 +0300 Subject: [PATCH 0/3] virtio-mmio: handle BE guests on LE hosts In-Reply-To: <1381741495.3247.18.camel@hornet> References: <1381502171-8187-1-git-send-email-marc.zyngier@arm.com> <20131012182837.GC2089@redhat.com> <525BAA40.8070103@arm.com> <20131014085931.GB30954@redhat.com> <1381741495.3247.18.camel@hornet> Message-ID: <20131014104604.GC30954@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Oct 14, 2013 at 10:04:55AM +0100, Pawel Moll wrote: > On Mon, 2013-10-14 at 09:59 +0100, Michael S. Tsirkin wrote: > > On Mon, Oct 14, 2013 at 09:24:32AM +0100, Marc Zyngier wrote: > > > Hi Michael, > > > > > > On 12/10/13 19:28, Michael S. Tsirkin wrote: > > > > On Fri, Oct 11, 2013 at 03:36:08PM +0100, Marc Zyngier wrote: > > > >> This small patch series adds just enough kernel infrastructure and > > > >> fixes to allow a BE guest to use virtio-mmio on a LE host, provided > > > >> that the host actually supports such madness. > > > >> > > > >> This has been tested on arm64, with some fixes to KVM and a set of > > > >> changes to kvmtool, both which I am posting separately. > > > >> > > > >> A branch containing all the relevant changes is at: > > > >> git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/be-on-le-3.12-rc4 > > > >> > > > >> Cc: Rusty Russell > > > >> Cc: Michael S. Tsirkin > > > >> Cc: Pawel Moll > > > > > > > > We are changing the spec to make everything LE instead of > > > > the native endian. > > > > > > > > I think that'll fix the issue in a cleaner way. > > > > > > While I agree that it would solve the issue completely, it would also > > > break all BE users. Is that really an option? > > > > I proposed several ways to create "transitional devices" > > which can detect and switch to old interface at run-time. > > > > Pawel thinks that's not necessary so ... > > Don't wipe yourself with my name, please. > > You forgot to mention that the devices are versioned and the behavior of > the legacy devices remains unchanged. No existing implementation will be > broken. > > Pawe? > I'm sorry if what I wrote was misleading. What I meant is that under the proposed scheme, users with existing v1 drivers must configure a v1 device explicitly. According to the plan, drivers will be updated so they can work with both v1 devices and new v2 devices. But if you configure a v2 device, old drivers will not work. -- MST From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 0/3] virtio-mmio: handle BE guests on LE hosts Date: Mon, 14 Oct 2013 13:46:04 +0300 Message-ID: <20131014104604.GC30954@redhat.com> References: <1381502171-8187-1-git-send-email-marc.zyngier@arm.com> <20131012182837.GC2089@redhat.com> <525BAA40.8070103@arm.com> <20131014085931.GB30954@redhat.com> <1381741495.3247.18.camel@hornet> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Cc: Marc Zyngier , Rusty Russell , "kvmarm@lists.cs.columbia.edu" , "linux-arm-kernel@lists.infradead.org" , "kvm@vger.kernel.org" To: Pawel Moll Return-path: Content-Disposition: inline In-Reply-To: <1381741495.3247.18.camel@hornet> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: kvm.vger.kernel.org T24gTW9uLCBPY3QgMTQsIDIwMTMgYXQgMTA6MDQ6NTVBTSArMDEwMCwgUGF3ZWwgTW9sbCB3cm90 ZToKPiBPbiBNb24sIDIwMTMtMTAtMTQgYXQgMDk6NTkgKzAxMDAsIE1pY2hhZWwgUy4gVHNpcmtp biB3cm90ZToKPiA+IE9uIE1vbiwgT2N0IDE0LCAyMDEzIGF0IDA5OjI0OjMyQU0gKzAxMDAsIE1h cmMgWnluZ2llciB3cm90ZToKPiA+ID4gSGkgTWljaGFlbCwKPiA+ID4gCj4gPiA+IE9uIDEyLzEw LzEzIDE5OjI4LCBNaWNoYWVsIFMuIFRzaXJraW4gd3JvdGU6Cj4gPiA+ID4gT24gRnJpLCBPY3Qg MTEsIDIwMTMgYXQgMDM6MzY6MDhQTSArMDEwMCwgTWFyYyBaeW5naWVyIHdyb3RlOgo+ID4gPiA+ PiBUaGlzIHNtYWxsIHBhdGNoIHNlcmllcyBhZGRzIGp1c3QgZW5vdWdoIGtlcm5lbCBpbmZyYXN0 cnVjdHVyZSBhbmQKPiA+ID4gPj4gZml4ZXMgdG8gYWxsb3cgYSBCRSBndWVzdCB0byB1c2Ugdmly dGlvLW1taW8gb24gYSBMRSBob3N0LCBwcm92aWRlZAo+ID4gPiA+PiB0aGF0IHRoZSBob3N0IGFj dHVhbGx5IHN1cHBvcnRzIHN1Y2ggbWFkbmVzcy4KPiA+ID4gPj4KPiA+ID4gPj4gVGhpcyBoYXMg YmVlbiB0ZXN0ZWQgb24gYXJtNjQsIHdpdGggc29tZSBmaXhlcyB0byBLVk0gYW5kIGEgc2V0IG9m Cj4gPiA+ID4+IGNoYW5nZXMgdG8ga3ZtdG9vbCwgYm90aCB3aGljaCBJIGFtIHBvc3Rpbmcgc2Vw YXJhdGVseS4KPiA+ID4gPj4KPiA+ID4gPj4gQSBicmFuY2ggY29udGFpbmluZyBhbGwgdGhlIHJl bGV2YW50IGNoYW5nZXMgaXMgYXQ6Cj4gPiA+ID4+IGdpdDovL2dpdC5rZXJuZWwub3JnL3B1Yi9z Y20vbGludXgva2VybmVsL2dpdC9tYXovYXJtLXBsYXRmb3Jtcy5naXQga3ZtLWFybTY0L2JlLW9u LWxlLTMuMTItcmM0Cj4gPiA+ID4+Cj4gPiA+ID4+IENjOiBSdXN0eSBSdXNzZWxsIDxydXN0eUBy dXN0Y29ycC5jb20uYXU+Cj4gPiA+ID4+IENjOiBNaWNoYWVsIFMuIFRzaXJraW4gPG1zdEByZWRo YXQuY29tPgo+ID4gPiA+PiBDYzogUGF3ZWwgTW9sbCA8cGF3ZWwubW9sbEBhcm0uY29tPgo+ID4g PiA+IAo+ID4gPiA+IFdlIGFyZSBjaGFuZ2luZyB0aGUgc3BlYyB0byBtYWtlIGV2ZXJ5dGhpbmcg TEUgaW5zdGVhZCBvZgo+ID4gPiA+IHRoZSBuYXRpdmUgZW5kaWFuLgo+ID4gPiA+IAo+ID4gPiA+ IEkgdGhpbmsgdGhhdCdsbCBmaXggdGhlIGlzc3VlIGluIGEgY2xlYW5lciB3YXkuCj4gPiA+IAo+ ID4gPiBXaGlsZSBJIGFncmVlIHRoYXQgaXQgd291bGQgc29sdmUgdGhlIGlzc3VlIGNvbXBsZXRl bHksIGl0IHdvdWxkIGFsc28KPiA+ID4gYnJlYWsgYWxsIEJFIHVzZXJzLiBJcyB0aGF0IHJlYWxs eSBhbiBvcHRpb24/Cj4gPiAKPiA+IEkgcHJvcG9zZWQgc2V2ZXJhbCB3YXlzIHRvIGNyZWF0ZSAi dHJhbnNpdGlvbmFsIGRldmljZXMiCj4gPiB3aGljaCBjYW4gZGV0ZWN0IGFuZCBzd2l0Y2ggdG8g b2xkIGludGVyZmFjZSBhdCBydW4tdGltZS4KPiA+IAo+ID4gUGF3ZWwgdGhpbmtzIHRoYXQncyBu b3QgbmVjZXNzYXJ5IHNvIC4uLgo+IAo+IERvbid0IHdpcGUgeW91cnNlbGYgd2l0aCBteSBuYW1l LCBwbGVhc2UuCj4gCj4gWW91IGZvcmdvdCB0byBtZW50aW9uIHRoYXQgdGhlIGRldmljZXMgYXJl IHZlcnNpb25lZCBhbmQgdGhlIGJlaGF2aW9yIG9mCj4gdGhlIGxlZ2FjeSBkZXZpY2VzIHJlbWFp bnMgdW5jaGFuZ2VkLiBObyBleGlzdGluZyBpbXBsZW1lbnRhdGlvbiB3aWxsIGJlCj4gYnJva2Vu Lgo+IAo+IFBhd2XFggo+IAoKSSdtIHNvcnJ5IGlmIHdoYXQgSSB3cm90ZSB3YXMgbWlzbGVhZGlu Zy4KCldoYXQgSSBtZWFudCBpcyB0aGF0IHVuZGVyIHRoZSBwcm9wb3NlZCBzY2hlbWUsIHVzZXJz IHdpdGgKZXhpc3RpbmcgdjEgZHJpdmVycyBtdXN0IGNvbmZpZ3VyZSBhIHYxIGRldmljZSBleHBs aWNpdGx5LgoKQWNjb3JkaW5nIHRvIHRoZSBwbGFuLCBkcml2ZXJzIHdpbGwgYmUgdXBkYXRlZCBz byB0aGV5IGNhbgp3b3JrIHdpdGggYm90aCB2MSBkZXZpY2VzIGFuZCBuZXcgdjIgZGV2aWNlcy4K CkJ1dCBpZiB5b3UgY29uZmlndXJlIGEgdjIgZGV2aWNlLCBvbGQgZHJpdmVycwp3aWxsIG5vdCB3 b3JrLgoKLS0gCk1TVAoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QKbGludXgtYXJtLWtlcm5lbEBsaXN0 cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGlu Zm8vbGludXgtYXJtLWtlcm5lbAo=