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From: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"kevin.tian@intel.com" <kevin.tian@intel.com>,
	"fenghua.yu@intel.com" <fenghua.yu@intel.com>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"felix.kuehling@amd.com" <felix.kuehling@amd.com>,
	"robin.murphy@arm.com" <robin.murphy@arm.com>,
	"christian.koenig@amd.com" <christian.koenig@amd.com>,
	"hch@infradead.org" <hch@infradead.org>,
	"jgg@ziepe.ca" <jgg@ziepe.ca>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
	"zhangfei.gao@linaro.org" <zhangfei.gao@linaro.org>,
	"will@kernel.org" <will@kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: RE: [PATCH v7 21/24] iommu/arm-smmu-v3: Add stall support for platform devices
Date: Tue, 2 Jun 2020 10:31:29 +0000	[thread overview]
Message-ID: <1517c4d97b5849e6b6d32e7d7ed35289@huawei.com> (raw)
In-Reply-To: <20200602093836.GA1029680@myrica>

Hi Jean,

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-bounces@lists.infradead.org]
> On Behalf Of Jean-Philippe Brucker
> Sent: 02 June 2020 10:39
> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
> Cc: devicetree@vger.kernel.org; kevin.tian@intel.com; will@kernel.org;
> fenghua.yu@intel.com; jgg@ziepe.ca; linux-pci@vger.kernel.org;
> felix.kuehling@amd.com; hch@infradead.org; linux-mm@kvack.org;
> iommu@lists.linux-foundation.org; catalin.marinas@arm.com;
> zhangfei.gao@linaro.org; robin.murphy@arm.com;
> christian.koenig@amd.com; linux-arm-kernel@lists.infradead.org
> Subject: Re: [PATCH v7 21/24] iommu/arm-smmu-v3: Add stall support for
> platform devices
> 
> Hi Shameer,
> 
> On Mon, Jun 01, 2020 at 12:42:15PM +0000, Shameerali Kolothum Thodi
> wrote:
> > >  /* IRQ and event handlers */
> > > +static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64
> > > +*evt) {
> > > +	int ret;
> > > +	u32 perm = 0;
> > > +	struct arm_smmu_master *master;
> > > +	bool ssid_valid = evt[0] & EVTQ_0_SSV;
> > > +	u8 type = FIELD_GET(EVTQ_0_ID, evt[0]);
> > > +	u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
> > > +	struct iommu_fault_event fault_evt = { };
> > > +	struct iommu_fault *flt = &fault_evt.fault;
> > > +
> > > +	/* Stage-2 is always pinned at the moment */
> > > +	if (evt[1] & EVTQ_1_S2)
> > > +		return -EFAULT;
> > > +
> > > +	master = arm_smmu_find_master(smmu, sid);
> > > +	if (!master)
> > > +		return -EINVAL;
> > > +
> > > +	if (evt[1] & EVTQ_1_READ)
> > > +		perm |= IOMMU_FAULT_PERM_READ;
> > > +	else
> > > +		perm |= IOMMU_FAULT_PERM_WRITE;
> > > +
> > > +	if (evt[1] & EVTQ_1_EXEC)
> > > +		perm |= IOMMU_FAULT_PERM_EXEC;
> > > +
> > > +	if (evt[1] & EVTQ_1_PRIV)
> > > +		perm |= IOMMU_FAULT_PERM_PRIV;
> > > +
> > > +	if (evt[1] & EVTQ_1_STALL) {
> > > +		flt->type = IOMMU_FAULT_PAGE_REQ;
> > > +		flt->prm = (struct iommu_fault_page_request) {
> > > +			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
> > > +			.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]),
> > > +			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
> > > +			.perm = perm,
> > > +			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
> > > +		};
> > > +
> >
> > > +		if (ssid_valid)
> > > +			flt->prm.flags |=
> IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
> >
> > Do we need to set this for STALL mode only support? I had an issue
> > with this being set on a vSVA POC based on our D06 zip device(which is
> > a "fake " pci dev that supports STALL mode but no PRI). The issue is,
> > CMDQ_OP_RESUME doesn't have any ssid or SSV params and works on sid
> and stag only.
> 
> I don't understand the problem, arm_smmu_page_response() doesn't set SSID
> or SSV when sending a CMDQ_OP_RESUME. Could you detail the flow of a stall
> event and RESUME command in your prototype?  Are you getting issues with
> the host driver or the guest driver?

The issue is on the host side iommu_page_response(). The flow is something like
below.

Stall: Host:-

arm_smmu_handle_evt()
  iommu_report_device_fault()
    vfio_pci_iommu_dev_fault_handler()
      
Stall: Qemu:-

vfio_dma_fault_notifier_handler()
  inject_faults()
    smmuv3_inject_faults()

Stall: Guest:-

arm_smmu_handle_evt()
  iommu_report_device_fault()
    iommu_queue_iopf
  ...
  iopf_handle_group()
    iopf_handle_single()
      handle_mm_fault()
        iopf_complete()
           iommu_page_response()
             arm_smmu_page_response()
               arm_smmu_cmdq_issue_cmd(CMDQ_OP_RESUME)

Resume: Qemu:-

smmuv3_cmdq_consume(SMMU_CMD_RESUME)
  smmuv3_notify_page_resp()
    vfio:ioctl(page_response)  --> struct iommu_page_response is filled
                             with only version, grpid and code.

Resume: Host:-
  ioctl(page_response)
    iommu_page_response()  --> fails as the pending req has PASID_VALID flag
                             set and it checks for a match.
      arm_smmu_page_response()

Hope the above is clear.

> We do need to forward the SSV flag all the way to the guest driver, so the guest
> can find the faulting address space using the SSID. Once the guest handled the
> fault, then we don't send the SSID back to the host as part of the RESUME
> command.

True, the guest requires SSV flag to handle the page fault. But, as shown in the
flow above, the issue is on the host side iommu_page_response() where it
searches for a matching pending req based on pasid. Not sure we can bypass
that and call arm_smmu_page_response() directly but then have to delete the
pending req from the list as well.

Please let me know if there is a better way to handle the host side page
response.

Thanks,
Shameer

> Thanks,
> Jean
> 
> > Hence, it is difficult for
> > Qemu SMMUv3 to populate this fields while preparing a page response. I
> > can see that this flag is being checked in iopf_handle_single() (patch
> > 04/24) as well. For POC, I used a temp fix[1] to work around this. Please let
> me know your thoughts.
> >
> > Thanks,
> > Shameer
> >
> > 1.
> > https://github.com/hisilicon/kernel-dev/commit/99ff96146e924055f38d97a
> > 5897e4becfa378d15
> >
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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  reply	other threads:[~2020-06-02 10:31 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-19 17:54 [PATCH v7 00/24] iommu: Shared Virtual Addressing for SMMUv3 Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 01/24] mm: Add a PASID field to mm_struct Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 02/24] iommu/ioasid: Add ioasid references Jean-Philippe Brucker
2020-05-20  2:31   ` Lu Baolu
2020-05-19 17:54 ` [PATCH v7 03/24] iommu/sva: Add PASID helpers Jean-Philippe Brucker
2020-05-20  2:41   ` Lu Baolu
2020-05-19 17:54 ` [PATCH v7 04/24] iommu: Add a page fault handler Jean-Philippe Brucker
2020-05-20  6:42   ` Lu Baolu
2020-11-11 13:57     ` Jean-Philippe Brucker
2020-11-11 23:11       ` Lu Baolu
2020-05-29  9:18   ` Xiang Zheng
2020-11-11 13:57     ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 05/24] arm64: mm: Add asid_gen_match() helper Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 06/24] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 07/24] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-05-21 14:16   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 08/24] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 09/24] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 10/24] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 11/24] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 12/24] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-05-21 14:16   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 13/24] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-05-21 14:17   ` Will Deacon
2020-05-21 14:38     ` Marc Zyngier
2020-05-22 10:17       ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 14/24] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-05-21 14:17   ` Will Deacon
2020-05-19 17:54 ` [PATCH v7 15/24] iommu/arm-smmu-v3: Add SVA device feature Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 16/24] iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind() Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 17/24] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 18/24] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-05-21 11:12   ` Will Deacon
2020-05-27  3:00   ` Xiang Zheng
2020-05-27  8:41     ` Jean-Philippe Brucker
2020-08-28  9:28   ` Zenghui Yu
2020-09-16 14:11     ` Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 19/24] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 20/24] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2020-05-19 17:54 ` [PATCH v7 21/24] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-06-01 12:42   ` Shameerali Kolothum Thodi
2020-06-02  9:38     ` Jean-Philippe Brucker
2020-06-02 10:31       ` Shameerali Kolothum Thodi [this message]
2020-06-02 11:46         ` Jean-Philippe Brucker
2020-06-02 12:12           ` Shameerali Kolothum Thodi
2020-06-03  7:38             ` Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 22/24] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 23/24] PCI/ATS: Export PRI functions Jean-Philippe Brucker
2020-05-19 17:55 ` [PATCH v7 24/24] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker
2020-05-21 10:35 ` [PATCH v7 00/24] iommu: Shared Virtual Addressing for SMMUv3 Will Deacon
2020-05-21 14:17   ` Will Deacon

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