From: Nicolin Chen <nicolinc@nvidia.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: <jgg@nvidia.com>, <will@kernel.org>, <eric.auger@redhat.com>,
<kevin.tian@intel.com>, <baolu.lu@linux.intel.com>,
<joro@8bytes.org>, <shameerali.kolothum.thodi@huawei.com>,
<jean-philippe@linaro.org>,
<linux-arm-kernel@lists.infradead.org>, <iommu@lists.linux.dev>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 14/14] iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user
Date: Sun, 19 Mar 2023 18:32:03 -0700 [thread overview]
Message-ID: <ZBe3kxRXf+VbKy+m@Asurada-Nvidia> (raw)
In-Reply-To: <ZBOFcenanpRsGFzF@Asurada-Nvidia>
On Thu, Mar 16, 2023 at 02:09:08PM -0700, Nicolin Chen wrote:
> On Thu, Mar 16, 2023 at 02:58:39PM +0000, Robin Murphy wrote:
>
> > > > > > I really think UAPI should reflect the hardware and encode TG and TTL
> > > > > > directly. Especially since there's technically a flaw in the current
> > > > > > driver where we assume TTL in cases where it isn't actually known, thus
> > > > > > may potentially fail to invalidate level 2 block entries when removing a
> > > > > > level 1 table, since io-pgtable passes the level 3 granule in that case.
> > > > >
> > > > > Do you mean something like hw_info forwarding pgsize_bitmap/tg
> > > > > to the guest? Or the other direction?
> > > >
> > > > I mean if the interface wants to support range invalidations in a way
> > > > which works correctly, then it should ideally carry both the TG and TTL
> > > > fields from the guest command straight through to the host. If not, then
> > > > at the very least the host must always assume TTL=0, because it cannot
> > > > correctly infer otherwise once the guest command's original intent has
> > > > been lost.
> > >
> > > Oh, it's about hypervisor simply forwarding the entire CMD to
> > > the host side. Jason is suggesting a fast approach by letting
> > > host kernel read the CMDQ directly to get the raw CMD. Perhaps
> > > that would address this comments about TG/TTL too.
> >
> > That did cross my mind, but given the usage model, having host userspace
> > give guest memory whose contents it can't control (unless it pauses the
> > whole VM on all CPUs) directly to the host kernel just seems to invite
> > more potential problems than necessary. Commands aren't big, so I think
> > it's fair to expect the VMM to marshal them into host memory, and save
> > the host kernel from ever having to reason about any races or other
> > emulation details which may exist between a VM and its VMM.
>
> An invalidation ioctl is synchronously executed from the top
> level in QEMU when it traps any CMDQ_PROD write. So, either
> packing the fields of a command into a data structure or just
> forwarding the command directly, it seems to be the same for
> the matter of worrying about race conditions?
I think I misread your reply here :)
What you suggested is exactly forwarding the command v.s. host
reading guest's command queue memory.
Although I haven't fully got what Jason's "sorting" approach,
this could already simplify the data structure holding all the
fields, by passing a "__u64 cmds[2]" alone. A sample code:
+struct iommu_hwpt_invalidate_arm_smmuv3 {
+ struct iommu_iova_range range;
+ __u64 cmd[2];
+};
then...
+ cmd[0] = inv_info->cmd[0];
+ cmd[1] = inv_info->cmd[1];
+ switch (cmd[0] & 0xff) {
+ case CMDQ_OP_TLBI_NSNH_ALL:
+ cmd[0] &= ~0xffULL;
+ cmd[0] |= CMDQ_OP_TLBI_NH_ALL;
+ fallthrough;
+ case CMDQ_OP_TLBI_NH_VA:
+ case CMDQ_OP_TLBI_NH_VAA:
+ case CMDQ_OP_TLBI_NH_ALL:
+ case CMDQ_OP_TLBI_NH_ASID:
+ cmd[0] &= ~CMDQ_TLBI_0_VMID;
+ cmd[0] |= FIELD_PREP(CMDQ_TLBI_0_VMID, smmu_domain->s2->s2_cfg.vmid);
+ arm_smmu_cmdq_issue_cmdlist(smmu, cmd, 1, true);
+ break;
+ case CMDQ_OP_CFGI_CD:
+ case CMDQ_OP_CFGI_CD_ALL:
+ arm_smmu_sync_cd(smmu_domain,
+ FIELD_GET(CMDQ_CFGI_0_SSID, cmd[0]), false);
+ break;
+ default:
+ return;
+ }
We could probably do a batch forwarding to if it's worthy?
Thanks
Nic
next prev parent reply other threads:[~2023-03-20 1:38 UTC|newest]
Thread overview: 165+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-09 10:53 [PATCH v1 00/14] Add Nested Translation Support for SMMUv3 Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper Nicolin Chen
2023-03-09 12:51 ` Robin Murphy
2023-03-09 14:19 ` Jason Gunthorpe
2023-03-09 19:04 ` Robin Murphy
2023-03-10 0:23 ` Jason Gunthorpe
2023-03-10 8:41 ` Eric Auger
2023-03-10 15:55 ` Jason Gunthorpe
2023-03-16 1:21 ` Nicolin Chen
2023-03-16 18:42 ` Robin Murphy
2023-03-16 20:01 ` Nicolin Chen
2023-03-20 12:51 ` Jason Gunthorpe
2023-03-10 10:14 ` Eric Auger
2023-03-10 15:33 ` Jason Gunthorpe
2023-03-10 15:44 ` Shameerali Kolothum Thodi
2023-03-10 15:56 ` Jason Gunthorpe
2023-03-10 16:07 ` Shameerali Kolothum Thodi
2023-03-10 16:21 ` Jason Gunthorpe
2023-03-10 16:30 ` Shameerali Kolothum Thodi
2023-03-10 17:03 ` Jason Gunthorpe
2023-03-22 16:07 ` Eric Auger
2023-03-22 17:02 ` Jason Gunthorpe
2023-03-22 17:41 ` Eric Auger
2023-03-22 18:07 ` Jason Gunthorpe
2023-03-16 19:51 ` Nicolin Chen
2023-03-16 19:56 ` Shameerali Kolothum Thodi
2023-03-22 15:44 ` Eric Auger
2023-03-09 10:53 ` [PATCH v1 02/14] iommufd: Add nesting related data structures for ARM SMMUv3 Nicolin Chen
2023-03-09 13:42 ` Jean-Philippe Brucker
2023-03-09 14:48 ` Jason Gunthorpe
2023-03-09 18:26 ` Jean-Philippe Brucker
2023-03-09 21:01 ` Jason Gunthorpe
2023-03-10 12:16 ` Jean-Philippe Brucker
2023-03-10 14:52 ` Robin Murphy
2023-03-10 15:25 ` Jason Gunthorpe
2023-03-10 15:57 ` Robin Murphy
2023-03-10 16:03 ` Jason Gunthorpe
2023-03-17 10:10 ` Tian, Kevin
2023-03-17 10:04 ` Tian, Kevin
2023-03-10 4:50 ` Nicolin Chen
2023-03-10 12:54 ` Jean-Philippe Brucker
2023-03-10 14:00 ` Jason Gunthorpe
2023-03-10 16:06 ` Jason Gunthorpe
2023-03-16 0:59 ` Nicolin Chen
2023-03-09 15:26 ` Shameerali Kolothum Thodi
2023-03-09 15:40 ` Jason Gunthorpe
2023-03-09 15:51 ` Shameerali Kolothum Thodi
2023-03-09 15:59 ` Jason Gunthorpe
2023-03-09 16:07 ` Shameerali Kolothum Thodi
2023-03-10 5:26 ` Nicolin Chen
2023-03-10 5:36 ` Nicolin Chen
2023-03-10 12:55 ` Jason Gunthorpe
2023-03-10 5:18 ` Nicolin Chen
2023-03-10 5:04 ` Nicolin Chen
2023-03-10 11:33 ` Eric Auger
2023-03-10 12:51 ` Jason Gunthorpe
2023-03-17 10:17 ` Tian, Kevin
2023-03-09 10:53 ` [PATCH v1 03/14] iommufd/device: Setup MSI on kernel-managed domains Nicolin Chen
2023-03-10 16:45 ` Eric Auger
2023-03-11 0:17 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 04/14] iommu/arm-smmu-v3: Add arm_smmu_hw_info Nicolin Chen
2023-03-09 13:03 ` Robin Murphy
2023-03-10 1:17 ` Nicolin Chen
2023-03-10 15:28 ` Robin Murphy
2023-03-16 0:13 ` Nicolin Chen
2023-03-16 15:19 ` Robin Murphy
2023-03-16 20:06 ` Nicolin Chen
2023-04-12 7:47 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 05/14] iommu/arm-smmu-v3: Remove ARM_SMMU_DOMAIN_NESTED Nicolin Chen
2023-03-10 16:39 ` Eric Auger
2023-03-10 17:05 ` Jason Gunthorpe
2023-03-11 0:24 ` Nicolin Chen
2023-03-11 0:23 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 06/14] iommu/arm-smmu-v3: Unset corresponding STE fields when s2_cfg is NULL Nicolin Chen
2023-03-09 13:13 ` Robin Murphy
2023-03-09 18:24 ` Shameerali Kolothum Thodi
2023-03-10 1:54 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 07/14] iommu/arm-smmu-v3: Add STRTAB_STE_0_CFG_NESTED for 2-stage translation Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 08/14] iommu/arm-smmu-v3: Prepare for nested domain support Nicolin Chen
2023-03-10 20:39 ` Robin Murphy
2023-03-11 12:40 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 09/14] iommu/arm-smmu-v3: Implement arm_smmu_get_unmanaged_domain Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 10/14] iommu/arm-smmu-v3: Pass in user_cfg to arm_smmu_domain_finalise Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 11/14] iommu/arm-smmu-v3: Add arm_smmu_domain_alloc_user Nicolin Chen
2023-03-24 15:28 ` Eric Auger
2023-03-24 17:40 ` Nicolin Chen
2023-03-24 17:50 ` Jason Gunthorpe
2023-03-24 18:00 ` Nicolin Chen
2023-03-24 15:33 ` Eric Auger
2023-03-24 17:43 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 12/14] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED type of allocations Nicolin Chen
2023-03-09 13:20 ` Robin Murphy
2023-03-09 14:28 ` Robin Murphy
2023-03-10 1:34 ` Nicolin Chen
2023-03-24 15:44 ` Eric Auger
2023-03-24 16:30 ` Jason Gunthorpe
2023-03-24 17:50 ` Nicolin Chen
2023-03-24 17:51 ` Jason Gunthorpe
2023-03-24 17:55 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 13/14] iommu/arm-smmu-v3: Add CMDQ_OP_TLBI_NH_VAA and CMDQ_OP_TLBI_NH_ALL Nicolin Chen
2023-03-09 13:44 ` Robin Murphy
2023-03-10 1:19 ` Nicolin Chen
2023-03-09 10:53 ` [PATCH v1 14/14] iommu/arm-smmu-v3: Add arm_smmu_cache_invalidate_user Nicolin Chen
2023-03-09 14:49 ` Robin Murphy
2023-03-09 15:31 ` Jason Gunthorpe
2023-03-10 4:20 ` Nicolin Chen
2023-03-10 16:19 ` Jason Gunthorpe
2023-03-11 11:56 ` Nicolin Chen
2023-03-11 12:53 ` Nicolin Chen
2023-03-20 13:03 ` Jason Gunthorpe
2023-03-20 15:56 ` Nicolin Chen
2023-03-20 16:04 ` Jason Gunthorpe
2023-03-20 16:59 ` Nicolin Chen
2023-03-20 18:45 ` Jason Gunthorpe
2023-03-20 21:22 ` Nicolin Chen
2023-03-20 22:19 ` Jason Gunthorpe
2023-03-22 20:57 ` Nicolin Chen
2023-03-23 12:17 ` Jason Gunthorpe
2023-03-17 9:41 ` Tian, Kevin
2023-03-17 14:24 ` Nicolin Chen
2023-03-20 12:59 ` Jason Gunthorpe
2023-03-20 16:12 ` Nicolin Chen
2023-03-20 18:00 ` Jason Gunthorpe
2023-03-21 8:34 ` Tian, Kevin
2023-03-21 11:48 ` Jason Gunthorpe
2023-03-22 6:42 ` Nicolin Chen
2023-03-22 12:43 ` Jason Gunthorpe
2023-03-22 17:11 ` Nicolin Chen
2023-03-22 17:28 ` Jason Gunthorpe
2023-03-22 19:21 ` Nicolin Chen
2023-03-22 19:41 ` Jason Gunthorpe
2023-03-22 20:43 ` Nicolin Chen
2023-03-23 12:16 ` Jason Gunthorpe
2023-03-23 18:13 ` Nicolin Chen
2023-03-23 18:27 ` Jason Gunthorpe
2023-03-24 9:02 ` Tian, Kevin
2023-03-24 14:57 ` Jason Gunthorpe
2023-03-24 17:35 ` Nicolin Chen
2023-03-28 3:03 ` Tian, Kevin
2023-03-24 8:47 ` Tian, Kevin
2023-03-24 14:44 ` Jason Gunthorpe
2023-03-28 2:48 ` Tian, Kevin
2023-03-28 12:26 ` Jason Gunthorpe
2023-03-31 8:09 ` Tian, Kevin
2023-03-17 9:24 ` Tian, Kevin
2023-03-10 3:51 ` Nicolin Chen
2023-03-10 17:53 ` Robin Murphy
2023-03-10 18:49 ` Jason Gunthorpe
2023-03-11 12:38 ` Nicolin Chen
2023-03-13 13:07 ` Robin Murphy
2023-03-16 0:01 ` Nicolin Chen
2023-03-16 14:58 ` Robin Murphy
2023-03-16 21:09 ` Nicolin Chen
2023-03-20 1:32 ` Nicolin Chen [this message]
2023-03-20 13:11 ` Jason Gunthorpe
2023-03-20 15:28 ` Nicolin Chen
2023-03-20 16:01 ` Jason Gunthorpe
2023-03-20 16:35 ` Nicolin Chen
2023-03-20 18:07 ` Jason Gunthorpe
2023-03-20 20:46 ` Nicolin Chen
2023-03-20 22:14 ` Jason Gunthorpe
2023-03-22 5:14 ` Nicolin Chen
2023-03-24 8:55 ` Tian, Kevin
2023-03-17 9:47 ` Tian, Kevin
2023-03-17 14:16 ` Nicolin Chen
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