On Wed, Feb 15, 2017 at 5:50 PM, Alex Williamson <alex.william...@redhat.com > wrote:
> On Wed, 15 Feb 2017 17:05:35 -0500 > Jintack Lim <jint...@cs.columbia.edu> wrote: > > > On Tue, Feb 14, 2017 at 9:52 PM, Peter Xu <pet...@redhat.com> wrote: > > > > > On Tue, Feb 14, 2017 at 07:50:39AM -0500, Jintack Lim wrote: > > > > > > [...] > > > > > > > > > >> > I misunderstood what you said? > > > > > > > > > > > > > > I failed to understand why an vIOMMU could help boost > performance. > > > :( > > > > > > > Could you provide your command line here so that I can try to > > > > > > > reproduce? > > > > > > > > > > > > Sure. This is the command line to launch L1 VM > > > > > > > > > > > > qemu-system-x86_64 -M q35,accel=kvm,kernel-irqchip=split \ > > > > > > -m 12G -device intel-iommu,intremap=on,eim=off,caching-mode=on \ > > > > > > -drive file=/mydata/guest0.img,format=raw --nographic -cpu host > \ > > > > > > -smp 4,sockets=4,cores=1,threads=1 \ > > > > > > -device vfio-pci,host=08:00.0,id=net0 > > > > > > > > > > > > And this is for L2 VM. > > > > > > > > > > > > ./qemu-system-x86_64 -M q35,accel=kvm \ > > > > > > -m 8G \ > > > > > > -drive file=/vm/l2guest.img,format=raw --nographic -cpu host \ > > > > > > -device vfio-pci,host=00:03.0,id=net0 > > > > > > > > > > ... here looks like these are command lines for L1/L2 guest, rather > > > > > than L1 guest with/without vIOMMU? > > > > > > > > > > > > > That's right. I thought you were asking about command lines for L1/L2 > > > guest > > > > :(. > > > > I think I made the confusion, and as I said above, I didn't mean to > talk > > > > about the performance of L1 guest with/without vIOMMO. > > > > We can move on! > > > > > > I see. Sure! :-) > > > > > > [...] > > > > > > > > > > > > > Then, I *think* above assertion you encountered would fail only if > > > > > prev == 0 here, but I still don't quite sure why was that > happening. > > > > > Btw, could you paste me your "lspci -vvv -s 00:03.0" result in > your L1 > > > > > guest? > > > > > > > > > > > > > Sure. This is from my L1 guest. > > > > > > Hmm... I think I found the problem... > > > > > > > > > > > root@guest0:~# lspci -vvv -s 00:03.0 > > > > 00:03.0 Network controller: Mellanox Technologies MT27500 Family > > > > [ConnectX-3] > > > > Subsystem: Mellanox Technologies Device 0050 > > > > Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- > > > > Stepping- SERR+ FastB2B- DisINTx+ > > > > Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- > <TAbort- > > > > <MAbort- >SERR- <PERR- INTx- > > > > Latency: 0, Cache Line Size: 64 bytes > > > > Interrupt: pin A routed to IRQ 23 > > > > Region 0: Memory at fe900000 (64-bit, non-prefetchable) [size=1M] > > > > Region 2: Memory at fe000000 (64-bit, prefetchable) [size=8M] > > > > Expansion ROM at fea00000 [disabled] [size=1M] > > > > Capabilities: [40] Power Management version 3 > > > > Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA > PME(D0-,D1-,D2-,D3hot-,D3cold- > > > ) > > > > Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME- > > > > Capabilities: [48] Vital Product Data > > > > Product Name: CX354A - ConnectX-3 QSFP > > > > Read-only fields: > > > > [PN] Part number: MCX354A-FCBT > > > > [EC] Engineering changes: A4 > > > > [SN] Serial number: MT1346X00791 > > > > [V0] Vendor specific: PCIe Gen3 x8 > > > > [RV] Reserved: checksum good, 0 byte(s) reserved > > > > Read/write fields: > > > > [V1] Vendor specific: N/A > > > > [YA] Asset tag: N/A > > > > [RW] Read-write area: 105 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 253 byte(s) free > > > > [RW] Read-write area: 252 byte(s) free > > > > End > > > > Capabilities: [9c] MSI-X: Enable+ Count=128 Masked- > > > > Vector table: BAR=0 offset=0007c000 > > > > PBA: BAR=0 offset=0007d000 > > > > Capabilities: [60] Express (v2) Root Complex Integrated Endpoint, > MSI 00 > > > > DevCap: MaxPayload 256 bytes, PhantFunc 0 > > > > ExtTag- RBE+ > > > > DevCtl: Report errors: Correctable- Non-Fatal+ Fatal+ Unsupported+ > > > > RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop- > > > > MaxPayload 256 bytes, MaxReadReq 4096 bytes > > > > DevSta: CorrErr+ UncorrErr- FatalErr- UnsuppReq+ AuxPwr- TransPend- > > > > DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR-, OBFF Not > > > > Supported > > > > DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis-, LTR-, OBFF > > > Disabled > > > > Capabilities: [100 v0] #00 > > > > > > Here we have the head of ecap capability as cap_id==0, then when we > > > boot the l2 guest with the same device, we'll first copy this > > > cap_id==0 cap, then when adding the 2nd ecap, we'll probably encounter > > > problem since pcie_find_capability_list() will thought there is no cap > > > at all (cap_id==0 is skipped). > > > > > > Do you want to try this "hacky patch" to see whether it works for you? > > > > > > > Thanks for following this up! > > > > I just tried this, and I got some different message this time. > > > > qemu-system-x86_64: vfio: Cannot reset device 0000:00:03.0, no available > > reset mechanism. > > qemu-system-x86_64: vfio: Cannot reset device 0000:00:03.0, no available > > reset mechanism. > > Possibly very true, it might affect the reliability of the device in > the l2 guest, but shouldn't prevent it from being assigned. What's the > reset mechanism on the physical device (lspci -vvv from host please). > Thanks, Alex. This is from the host (L0). 08:00.0 Network controller: Mellanox Technologies MT27500 Family [ConnectX-3] Subsystem: Mellanox Technologies Device 0050 Control: I/O- Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Interrupt: pin A routed to IRQ 31 Region 0: Memory at d9f00000 (64-bit, non-prefetchable) [disabled] [size=1M] Region 2: Memory at d5000000 (64-bit, prefetchable) [disabled] [size=8M] Expansion ROM at d9000000 [disabled] [size=1M] Capabilities: [40] Power Management version 3 Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D3 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME- Capabilities: [48] Vital Product Data Product Name: CX354A - ConnectX-3 QSFP Read-only fields: [PN] Part number: MCX354A-FCBT [EC] Engineering changes: A4 [SN] Serial number: MT1346X00624 [V0] Vendor specific: PCIe Gen3 x8 [RV] Reserved: checksum good, 0 byte(s) reserved Read/write fields: [V1] Vendor specific: N/A [YA] Asset tag: N/A [RW] Read-write area: 105 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 253 byte(s) free [RW] Read-write area: 252 byte(s) free End Capabilities: [9c] MSI-X: Enable- Count=128 Masked- Vector table: BAR=0 offset=0007c000 PBA: BAR=0 offset=0007d000 Capabilities: [60] Express (v2) Endpoint, MSI 00 DevCap: MaxPayload 512 bytes, PhantFunc 0, Latency L0s <64ns, L1 unlimited ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset- DevCtl: Report errors: Correctable- Non-Fatal+ Fatal+ Unsupported+ RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop- MaxPayload 256 bytes, MaxReadReq 4096 bytes DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend- LnkCap: Port #8, Speed 8GT/s, Width x8, ASPM L0s, Exit Latency L0s unlimited, L1 unlimited ClockPM- Surprise- LLActRep- BwNot- LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk+ ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt- LnkSta: Speed 8GT/s, Width x8, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt- DevCap2: Completion Timeout: Range ABCD, TimeoutDis+, LTR-, OBFF Not Supported DevCtl2: Completion Timeout: 65ms to 210ms, TimeoutDis-, LTR-, OBFF Disabled LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis- Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS- Compliance De-emphasis: -6dB LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete+, EqualizationPhase1+ EqualizationPhase2+, EqualizationPhase3+, LinkEqualizationRequest- Capabilities: [c0] Vendor Specific Information: Len=18 <?> Capabilities: [100 v1] Alternative Routing-ID Interpretation (ARI) ARICap: MFVC- ACS-, Next Function: 0 ARICtl: MFVC- ACS-, Function Group: 0 Capabilities: [148 v1] Device Serial Number f4-52-14-03-00-15-51-10 Capabilities: [154 v2] Advanced Error Reporting UESta: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol- UEMsk: DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt+ UnxCmplt+ RxOF- MalfTLP- ECRC- UnsupReq- ACSViol- UESvrt: DLP+ SDES- TLP+ FCP+ CmpltTO+ CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC+ UnsupReq- ACSViol- CESta: RxErr- BadTLP- BadDLLP- Rollover- Timeout- NonFatalErr- CEMsk: RxErr+ BadTLP+ BadDLLP+ Rollover+ Timeout+ NonFatalErr+ AERCap: First Error Pointer: 00, GenCap+ CGenEn- ChkCap+ ChkEn- Capabilities: [18c v1] #19 Kernel driver in use: vfio-pci Thanks, > > Alex > >