diff mbox series

[RFC,06/12] iommu: Add mmu_notifier to sva domain

Message ID 20231017032045.114868-8-tina.zhang@intel.com
State New
Headers
Series iommu/vt-d: Remove superfluous IOMMU IOTLB invalidations |

Commit Message

Zhang, Tina Oct. 17, 2023, 3:20 a.m. UTC 
  Devices attached to shared virtual addressing (SVA) domain are allowed to
use the same virtual addresses with processor, and this functionality is
called shared virtual memory. When shared virtual memory is being used,
it's the sva domain's responsibility to keep device TLB cache and the CPU
cache in sync. Hence add mmu_notifier to sva domain.

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---
 include/linux/iommu.h | 2 ++
 1 file changed, 2 insertions(+)

Comments

Jason Gunthorpe Oct. 23, 2023, 6:35 p.m. UTC | #1 
On Tue, Oct 17, 2023 at 11:20:39AM +0800, Tina Zhang wrote:
> Devices attached to shared virtual addressing (SVA) domain are allowed to
> use the same virtual addresses with processor, and this functionality is
> called shared virtual memory. When shared virtual memory is being used,
> it's the sva domain's responsibility to keep device TLB cache and the CPU
> cache in sync. Hence add mmu_notifier to sva domain.
> 
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>
> ---
>  include/linux/iommu.h | 2 ++
>  1 file changed, 2 insertions(+)

You should look at how arm smmuv3 ended up after I went over it to
make similar changes, I think you should take this patch

https://lore.kernel.org/linux-iommu/20-v1-afbb86647bbd+5-smmuv3_newapi_p2_jgg@nvidia.com/

into this series (maybe drop the arm part)

And copy the same basic structure for how the mmu notifier works.

It would also be nice if alot of the 'if_sva' tests could be avoided,
smmu didn't end up with those..

In the guts of the pasid handling sva shouldn't be special beyond a
different source for the pgd.

Jason
Zhang, Tina Nov. 1, 2023, 11:58 a.m. UTC | #2 
Hi Jason,

> -----Original Message-----
> From: Jason Gunthorpe <jgg@ziepe.ca>
> Sent: Tuesday, October 24, 2023 2:35 AM
> To: Zhang, Tina <tina.zhang@intel.com>
> Cc: iommu@lists.linux.dev; linux-kernel@vger.kernel.org; kvm@vger.kernel.org;
> David Woodhouse <dwmw2@infradead.org>; Lu Baolu
> <baolu.lu@linux.intel.com>; Joerg Roedel <joro@8bytes.org>; Tian, Kevin
> <kevin.tian@intel.com>
> Subject: Re: [RFC PATCH 06/12] iommu: Add mmu_notifier to sva domain
> 
> 
> On Tue, Oct 17, 2023 at 11:20:39AM +0800, Tina Zhang wrote:
> > Devices attached to shared virtual addressing (SVA) domain are allowed
> > to use the same virtual addresses with processor, and this
> > functionality is called shared virtual memory. When shared virtual
> > memory is being used, it's the sva domain's responsibility to keep
> > device TLB cache and the CPU cache in sync. Hence add mmu_notifier to sva
> domain.
> >
> > Signed-off-by: Tina Zhang <tina.zhang@intel.com>
> > ---
> >  include/linux/iommu.h | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> You should look at how arm smmuv3 ended up after I went over it to make
> similar changes, I think you should take this patch
> 
> https://lore.kernel.org/linux-iommu/20-v1-afbb86647bbd+5-
> smmuv3_newapi_p2_jgg@nvidia.com/
> 
> into this series (maybe drop the arm part)
Good suggestion. The new domain_alloc_sva() callback allows drivers to fully initialize sva domain that is what we need. I'll take the domain_alloc_sva() part as a patch and include it in this patch-set. Thanks.

> 
> And copy the same basic structure for how the mmu notifier works.
> 
> It would also be nice if alot of the 'if_sva' tests could be avoided, smmu didn't
> end up with those..
Agree. With the help of domain_alloc_sva() callback, I think most of the if_sva brought by this RFC version can be reduced, as we can reuse fields from dmar_domain (or add new ones if necessary) and initialize them in domain_alloc_sva().

Regards,
-Tina
> 
> In the guts of the pasid handling sva shouldn't be special beyond a different
> source for the pgd.
> 
> Jason
diff mbox series

Patch

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 19b5ae2303ff..afb566230427 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -7,6 +7,7 @@ 
 #ifndef __LINUX_IOMMU_H
 #define __LINUX_IOMMU_H
 
+#include <linux/mmu_notifier.h>
 #include <linux/scatterlist.h>
 #include <linux/device.h>
 #include <linux/types.h>
@@ -114,6 +115,7 @@  struct iommu_domain {
 			 * protected by iommu_sva_lock.
 			 */
 			struct list_head next;
+			struct mmu_notifier notifier;
 		};
 	};
 };