[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <BN9PR11MB52765DEC46616F67185B1F1F8CAF9@BN9PR11MB5276.namprd11.prod.outlook.com>
Date: Fri, 17 Jun 2022 07:43:40 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>,
"Raj, Ashok" <ashok.raj@...el.com>
CC: Jean-Philippe Brucker <jean-philippe@...aro.org>,
"Jiang, Dave" <dave.jiang@...el.com>,
Robin Murphy <robin.murphy@....com>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Christoph Hellwig" <hch@...radead.org>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Vinod Koul <vkoul@...nel.org>,
"Pan, Jacob jun" <jacob.jun.pan@...el.com>,
Jason Gunthorpe <jgg@...dia.com>, Will Deacon <will@...nel.org>
Subject: RE: [PATCH v8 04/11] iommu: Add sva iommu_domain support
> From: Baolu Lu
> Sent: Friday, June 10, 2022 3:16 PM
> >
> >> +#define __IOMMU_DOMAIN_HOST_VA (1U << 5) /* Host CPU virtual
> address */
> >
> > Do you mean general CPU VA? or Host CPU VA, I'm reading the latter as
> 2nd
> > stage?
>
> Host CPU VA. In the near future, we will add another flag _GUEST_VA, so
> that the shared page table types are distiguished.
How does the kernel knows that an user page table translates guest VA?
IMHO I don't think the kernel should care about it except managing
all the aspects related to the user page table itself...
>
> >
> >> +
> >> /*
> >> * This are the possible domain-types
> >> *
> >> @@ -86,15 +89,24 @@ struct iommu_domain_geometry {
> >> #define IOMMU_DOMAIN_DMA_FQ
> (__IOMMU_DOMAIN_PAGING | \
> >> __IOMMU_DOMAIN_DMA_API | \
> >> __IOMMU_DOMAIN_DMA_FQ)
> >> +#define IOMMU_DOMAIN_SVA (__IOMMU_DOMAIN_SHARED |
> \
> >> + __IOMMU_DOMAIN_HOST_VA)
> >
> > Doesn't shared automatically mean CPU VA? Do we need another flag?
>
> Yes. Shared means CPU VA, but there're many types. Besides above two, we
> also see the shared KVM/EPT.
>
Will the two sharing scenarios share any common code? If not then
having a separate flag bit is meaningless.
It might be more straightforward to be:
#define IOMMU_DOMAIN_SVA __IOMMU_DOMAIN_SVA
#define IOMMU_DOMAIN_KVM __IOMMU_DOMAIN_KVM
#define IOMMU_DOMAIN_USER __IOMMU_DOMAIN_USER
Thanks
Kevin
Powered by blists - more mailing lists