Re: [PATCH RFC v1 12/15] iommu/virtio: Add support for INVALIDATE request

Vivek Kumar Gautam
2021-03-04T06:18:35Z

Hi Jacob, Kevin,

On 3/4/21 11:28 AM, Tian, Kevin wrote:
>> From: Jacob Pan <jacob.jun.pan@linux.intel.com>
>> Sent: Thursday, March 4, 2021 2:29 AM
>>
>> Hi Vivek,
>>
>> On Fri, 15 Jan 2021 17:43:39 +0530, Vivek Gautam <vivek.gautam@arm.com>
>> wrote:
>>
>>> From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>>>
>>> Add support for tlb invalidation ops that can send invalidation
>>> requests to back-end virtio-iommu when stage-1 page tables are
>>> supported.
>>>
>> Just curious if it possible to reuse the iommu uapi for invalidation and others.
>> When we started out designing the iommu uapi, the intention was to support
>> both emulated and virtio iommu.
>
> IIUC this patch is about the protocol between virtio-iommu frontend and backend.
> After the virtio-iommu backend receives invalidation ops, it then needs to
> forward the request to the host IOMMU driver through the existing iommu
> uapi that you referred to, as a emulated VT-d or SMMU would do.

Thanks a lot for looking at the patch.

Yes this patch is to provide the front-end virtio interface for
invalidation requests during map/unmap and when flushing the pasid
tables when virtio-iommu requested pasid table (in other words cd tables
for arm-smmu-v3) from the iommu-pasid-table library.
The kvmtool back-end virtio driver forwards these requests to vfio
driver which then makes use of iommu uapi to finally request host iommu
driver for handling these invalidations.

Regards
Vivek

>
> Thanks
> Kevin
>
>>
>>> Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>>> [Vivek: Refactoring the iommu_flush_ops, and adding only one pasid sync
>>> op that's needed with current iommu-pasid-table infrastructure.
>>> Also updating uapi defines as required by latest changes]
>>> Signed-off-by: Vivek Gautam <vivek.gautam@arm.com>
>>> Cc: Joerg Roedel <joro@8bytes.org>
>>> Cc: Will Deacon <will.deacon@arm.com>
>>> Cc: Michael S. Tsirkin <mst@redhat.com>
>>> Cc: Robin Murphy <robin.murphy@arm.com>
>>> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
>>> Cc: Eric Auger <eric.auger@redhat.com>
>>> Cc: Alex Williamson <alex.williamson@redhat.com>
>>> Cc: Kevin Tian <kevin.tian@intel.com>
>>> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
>>> Cc: Liu Yi L <yi.l.liu@intel.com>
>>> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>>> Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>
>>> ---
>>> drivers/iommu/virtio-iommu.c | 95
>> ++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 95 insertions(+)
>>>
>>> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
>>> index ae5dfd3f8269..004ea94e3731 100644
>>> --- a/drivers/iommu/virtio-iommu.c
>>> +++ b/drivers/iommu/virtio-iommu.c
>>> @@ -13,6 +13,7 @@
>>> #include <linux/freezer.h>
>>> #include <linux/interval_tree.h>
>>> #include <linux/iommu.h>
>>> +#include <linux/io-pgtable.h>
>>> #include <linux/module.h>
>>> #include <linux/of_iommu.h>
>>> #include <linux/of_platform.h>
>>> @@ -63,6 +64,8 @@ struct viommu_mapping {
>>> };
>>>
>>> struct viommu_mm {
>>> + int pasid;
>>> + u64 archid;
>>> struct io_pgtable_ops *ops;
>>> struct viommu_domain *domain;
>>> };
>>> @@ -692,6 +695,98 @@ static void viommu_event_handler(struct
>> virtqueue
>>> *vq) virtqueue_kick(vq);
>>> }
>>>
>>> +/* PASID and pgtable APIs */
>>> +
>>> +static void __viommu_flush_pasid_tlb_all(struct viommu_domain
>> *vdomain,
>>> + int pasid, u64 arch_id, int
>>> type) +{
>>> + struct virtio_iommu_req_invalidate req = {
>>> + .head.type = VIRTIO_IOMMU_T_INVALIDATE,
>>> + .inv_gran =
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_G_PASID),
>>> + .flags =
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_F_PASID),
>>> + .inv_type = cpu_to_le32(type),
>>> +
>>> + .domain = cpu_to_le32(vdomain->id),
>>> + .pasid = cpu_to_le32(pasid),
>>> + .archid = cpu_to_le64(arch_id),
>>> + };
>>> +
>>> + if (viommu_send_req_sync(vdomain->viommu, &req, sizeof(req)))
>>> + pr_debug("could not send invalidate request\n");
>>> +}
>>> +
>>> +static void viommu_flush_tlb_add(struct iommu_iotlb_gather *gather,
>>> + unsigned long iova, size_t granule,
>>> + void *cookie)
>>> +{
>>> + struct viommu_mm *viommu_mm = cookie;
>>> + struct viommu_domain *vdomain = viommu_mm->domain;
>>> + struct iommu_domain *domain = &vdomain->domain;
>>> +
>>> + iommu_iotlb_gather_add_page(domain, gather, iova, granule);
>>> +}
>>> +
>>> +static void viommu_flush_tlb_walk(unsigned long iova, size_t size,
>>> + size_t granule, void *cookie)
>>> +{
>>> + struct viommu_mm *viommu_mm = cookie;
>>> + struct viommu_domain *vdomain = viommu_mm->domain;
>>> + struct virtio_iommu_req_invalidate req = {
>>> + .head.type = VIRTIO_IOMMU_T_INVALIDATE,
>>> + .inv_gran = cpu_to_le32(VIRTIO_IOMMU_INVAL_G_VA),
>>> + .inv_type =
>> cpu_to_le32(VIRTIO_IOMMU_INV_T_IOTLB),
>>> + .flags =
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_F_ARCHID), +
>>> + .domain = cpu_to_le32(vdomain->id),
>>> + .pasid = cpu_to_le32(viommu_mm->pasid),
>>> + .archid = cpu_to_le64(viommu_mm->archid),
>>> + .virt_start = cpu_to_le64(iova),
>>> + .nr_pages = cpu_to_le64(size / granule),
>>> + .granule = ilog2(granule),
>>> + };
>>> +
>>> + if (viommu_add_req(vdomain->viommu, &req, sizeof(req)))
>>> + pr_debug("could not add invalidate request\n");
>>> +}
>>> +
>>> +static void viommu_flush_tlb_all(void *cookie)
>>> +{
>>> + struct viommu_mm *viommu_mm = cookie;
>>> +
>>> + if (!viommu_mm->archid)
>>> + return;
>>> +
>>> + __viommu_flush_pasid_tlb_all(viommu_mm->domain,
>> viommu_mm->pasid,
>>> + viommu_mm->archid,
>>> + VIRTIO_IOMMU_INV_T_IOTLB);
>>> +}
>>> +
>>> +static struct iommu_flush_ops viommu_flush_ops = {
>>> + .tlb_flush_all = viommu_flush_tlb_all,
>>> + .tlb_flush_walk = viommu_flush_tlb_walk,
>>> + .tlb_add_page = viommu_flush_tlb_add,
>>> +};
>>> +
>>> +static void viommu_flush_pasid(void *cookie, int pasid, bool leaf)
>>> +{
>>> + struct viommu_domain *vdomain = cookie;
>>> + struct virtio_iommu_req_invalidate req = {
>>> + .head.type = VIRTIO_IOMMU_T_INVALIDATE,
>>> + .inv_gran =
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_G_PASID),
>>> + .inv_type =
>> cpu_to_le32(VIRTIO_IOMMU_INV_T_PASID),
>>> + .flags =
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_F_PASID), +
>>> + .domain = cpu_to_le32(vdomain->id),
>>> + .pasid = cpu_to_le32(pasid),
>>> + };
>>> +
>>> + if (leaf)
>>> + req.flags |=
>>> cpu_to_le32(VIRTIO_IOMMU_INVAL_F_LEAF); +
>>> + if (viommu_send_req_sync(vdomain->viommu, &req, sizeof(req)))
>>> + pr_debug("could not send invalidate request\n");
>>> +}
>>> +
>>> /* IOMMU API */
>>>
>>> static struct iommu_domain *viommu_domain_alloc(unsigned type)
>>
>>
>> Thanks,
>>
>> Jacob