Hello. What is the status of support for AMD''s (hardware/Pacifica) IOMMU in xen 3.0.2/3/4? Thanks Daniel _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Daniel McAllansmith > Sent: 22 February 2007 21:18 > To: xen-users@lists.xensource.com > Subject: [Xen-users] Xen support for AMD''s IOMMU > > Hello. > > What is the status of support for AMD''s (hardware/Pacifica) > IOMMU in xen > 3.0.2/3/4?Considering that we haven''t yet got a part available with IOMMU, the software to fullfill that function is pretty much a moot point, right? As to a direct answer to the question: There is no AMD IOMMU software in 3.0.{2,3,4}. There''s been a patch supplied by Mark Langsdorf to use the GART in the current AMD64 architecture for IOMMU operations (same way as the Linux kernel itself uses this portion of the chip). This is NOT to be confused with the REAL IOMMU design. -- Mats> > Thanks > Daniel > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
dfeustel@mindspring.com
2007-Feb-26 13:14 UTC
RE: [Xen-users] Xen support for AMD''s IOMMU
> > -----Original Message----- > > From: xen-users-bounces@lists.xensource.com=20 > > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of=20 > > Daniel McAllansmith > > Sent: 22 February 2007 21:18 > > To: xen-users@lists.xensource.com > > Subject: [Xen-users] Xen support for AMD''s IOMMU > >=20 > > Hello. > >=20 > > What is the status of support for AMD''s (hardware/Pacifica)=20 > > IOMMU in xen=20 > > 3.0.2/3/4? > > Considering that we haven''t yet got a part available with IOMMU, the > software to fullfill that function is pretty much a moot point, right?Barcelona, now rumored to become available in Q2 of 2007, is reported to support IOMMU. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > What is the status of support for AMD''s (hardware/Pacifica) > > IOMMU in xen > > 3.0.2/3/4? > > Considering that we haven''t yet got a part available with IOMMU, the > software to fullfill that function is pretty much a moot point, right?There''s some sort of memory permissions table for PCI devices though, isn''t there? I vaguely remember it being in the arch manual, but I haven''t actually known any software use it (at least in the context of Xen!) Cheers, Mark> As to a direct answer to the question: There is no AMD IOMMU software in > 3.0.{2,3,4}. There''s been a patch supplied by Mark Langsdorf to use the > GART in the current AMD64 architecture for IOMMU operations (same way as > the Linux kernel itself uses this portion of the chip). This is NOT to > be confused with the REAL IOMMU design. > > -- > Mats > > > Thanks > > Daniel > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xensource.com > > http://lists.xensource.com/xen-users > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: M.A. Williamson [mailto:maw48@hermes.cam.ac.uk] On > Behalf Of Mark Williamson > Sent: 26 February 2007 17:40 > To: xen-users@lists.xensource.com > Cc: Petersson, Mats; Daniel McAllansmith > Subject: Re: [Xen-users] Xen support for AMD''s IOMMU > > > > What is the status of support for AMD''s (hardware/Pacifica) > > > IOMMU in xen > > > 3.0.2/3/4? > > > > Considering that we haven''t yet got a part available with IOMMU, the > > software to fullfill that function is pretty much a moot > point, right? > > There''s some sort of memory permissions table for PCI devices > though, isn''t > there? I vaguely remember it being in the arch manual, but I haven''t > actually known any software use it (at least in the context of Xen!)Yes, that''s called "DEV" or "Device Exclusion Vector", and I''m also unaware of any software that is commonly available that uses this. It doesn''t actually solve the most commonly requested feature in IOMMU, which is the ability to run a HVM-guest using a PCI-device, and I wasn''t really considering the "security aspect" of IOMMU when I wrote my answer [and the DEV feature is definitely not usable to solve the PCI-device in HVM problem]. -- Mats> > Cheers, > Mark > > > As to a direct answer to the question: There is no AMD > IOMMU software in > > 3.0.{2,3,4}. There''s been a patch supplied by Mark > Langsdorf to use the > > GART in the current AMD64 architecture for IOMMU operations > (same way as > > the Linux kernel itself uses this portion of the chip). > This is NOT to > > be confused with the REAL IOMMU design. > > > > -- > > Mats > > > > > Thanks > > > Daniel > > > > > > _______________________________________________ > > > Xen-users mailing list > > > Xen-users@lists.xensource.com > > > http://lists.xensource.com/xen-users > > > > _______________________________________________ > > Xen-users mailing list > > Xen-users@lists.xensource.com > > http://lists.xensource.com/xen-users > > -- > Dave: Just a question. What use is a unicyle with no seat? > And no pedals! > Mark: To answer a question with a question: What use is a skateboard? > Dave: Skateboards have wheels. > Mark: My wheel has a wheel! > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> > There''s some sort of memory permissions table for PCI devices > > though, isn''t > > there? I vaguely remember it being in the arch manual, but I haven''t > > actually known any software use it (at least in the context of Xen!) > > Yes, that''s called "DEV" or "Device Exclusion Vector", and I''m also > unaware of any software that is commonly available that uses this. It > doesn''t actually solve the most commonly requested feature in IOMMU, > which is the ability to run a HVM-guest using a PCI-device,True.> and I wasn''t > really considering the "security aspect" of IOMMU when I wrote my answer > [and the DEV feature is definitely not usable to solve the PCI-device in > HVM problem].And I wasn''t really considering the HVM aspect when I wrote my question :-) Good point! Still, it''d be nice to support the DEV at some stage for purposes of reducing the trust level of PV domains with device access (i.e. there''s much less point putting a driver into an isolated domain if it can DMA everywhere anyhow!)... if it can be supported with sufficiently good performance, this would be kinda cool. Cheers, Mark> -- > Mats > > > Cheers, > > Mark > > > > > As to a direct answer to the question: There is no AMD > > > > IOMMU software in > > > > > 3.0.{2,3,4}. There''s been a patch supplied by Mark > > > > Langsdorf to use the > > > > > GART in the current AMD64 architecture for IOMMU operations > > > > (same way as > > > > > the Linux kernel itself uses this portion of the chip). > > > > This is NOT to > > > > > be confused with the REAL IOMMU design. > > > > > > -- > > > Mats > > > > > > > Thanks > > > > Daniel > > > > > > > > _______________________________________________ > > > > Xen-users mailing list > > > > Xen-users@lists.xensource.com > > > > http://lists.xensource.com/xen-users > > > > > > _______________________________________________ > > > Xen-users mailing list > > > Xen-users@lists.xensource.com > > > http://lists.xensource.com/xen-users > > > > -- > > Dave: Just a question. What use is a unicyle with no seat? > > And no pedals! > > Mark: To answer a question with a question: What use is a skateboard? > > Dave: Skateboards have wheels. > > Mark: My wheel has a wheel!-- Dave: Just a question. What use is a unicyle with no seat? And no pedals! Mark: To answer a question with a question: What use is a skateboard? Dave: Skateboards have wheels. Mark: My wheel has a wheel! _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tuesday 27 February 2007 01:50, Petersson, Mats wrote:> > Hello. > > > > What is the status of support for AMD''s (hardware/Pacifica) > > IOMMU in xen > > 3.0.2/3/4? > > Considering that we haven''t yet got a part available with IOMMU, the > software to fullfill that function is pretty much a moot point, right? > > As to a direct answer to the question: There is no AMD IOMMU software in > 3.0.{2,3,4}. There''s been a patch supplied by Mark Langsdorf to use the > GART in the current AMD64 architecture for IOMMU operations (same way as > the Linux kernel itself uses this portion of the chip). This is NOT to > be confused with the REAL IOMMU design.Ahhh, my mistake. I thought that both the DEV and the IOMMU had been added to the Pacifica architecture. When a ''real'' IOMMU is added (perhaps in the Barcelona), and supported, will that allow unmodified drivers on unmodified guest OS''s total control of devices? Or will IRQ delivery issues still require modifications to the guest driver/OS? Cheers Daniel _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: Daniel McAllansmith [mailto:dm.maillists@gmail.com] > Sent: 27 February 2007 00:07 > To: Petersson, Mats > Cc: xen-users@lists.xensource.com > Subject: Re: [Xen-users] Xen support for AMD''s IOMMU > > On Tuesday 27 February 2007 01:50, Petersson, Mats wrote: > > > Hello. > > > > > > What is the status of support for AMD''s (hardware/Pacifica) > > > IOMMU in xen > > > 3.0.2/3/4? > > > > Considering that we haven''t yet got a part available with IOMMU, the > > software to fullfill that function is pretty much a moot > point, right? > > > > As to a direct answer to the question: There is no AMD > IOMMU software in > > 3.0.{2,3,4}. There''s been a patch supplied by Mark > Langsdorf to use the > > GART in the current AMD64 architecture for IOMMU operations > (same way as > > the Linux kernel itself uses this portion of the chip). > This is NOT to > > be confused with the REAL IOMMU design. > > Ahhh, my mistake. I thought that both the DEV and the IOMMU > had been added to > the Pacifica architecture. > > When a ''real'' IOMMU is added (perhaps in the Barcelona), and > supported, will > that allow unmodified drivers on unmodified guest OS''s total > control of > devices? Or will IRQ delivery issues still require > modifications to the > guest driver/OS?There should be no need to modify any of the guest-OS''s driver. IRQ delivery will have to be handled via the hypervisor, but the guest should "know no difference (compared to real hardware)". Aside from a little extra latency, there shouldn''t be any real difference (and most modern hardware allows you to fire off more than one piece of work before an interrupt need to be acknowledged, so there shouldn''t be any BIG performance hit). To clarify: the hypervisor interaction is necessary, as the guest waiting for the interrupt may not be running at the time of the interrupt. So the HV takes the interrupt, and forwards a "virtual" interrupt to the guest. The guest then accesses the hardware as it sees fit, just like in "real hardware". The other difference will be that the interrupt controller itself is emulated in the hypervisor - in this case because there is only ONE real interrupt controller in the system, so the hypevisor needs to: 1. Make sure the interrupt controller is still working correctly for other guests (i.e. if one guest disables all interrupts, no other guest would ever run after that - we don''t really wish for that, do we?) 2. Be able to control the interrupt controller for it''s own purposes to allow the hypervisor full control of the hardware. -- Mats> > > Cheers > Daniel > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users