Messages in this thread | | | Subject | Re: [PATCH v6 01/10] iommu/vt-d: Enlightened PASID allocation | From | Lu Baolu <> | Date | Fri, 25 Oct 2019 09:39:56 +0800 |
| |
Hi,
On 10/24/19 1:55 AM, Jacob Pan wrote: > On Wed, 23 Oct 2019 09:53:04 +0800 > Lu Baolu <baolu.lu@linux.intel.com> wrote: > >> Hi Ashok, >> >> Thanks for reviewing the patch. >> >> On 10/23/19 8:45 AM, Raj, Ashok wrote: >>> On Tue, Oct 22, 2019 at 04:53:14PM -0700, Jacob Pan wrote: >>>> From: Lu Baolu <baolu.lu@linux.intel.com> >>>> >>>> If Intel IOMMU runs in caching mode, a.k.a. virtual IOMMU, the >>>> IOMMU driver should rely on the emulation software to allocate >>>> and free PASID IDs. The Intel vt-d spec revision 3.0 defines a >>>> register set to support this. This includes a capability register, >>>> a virtual command register and a virtual response register. Refer >>>> to section 10.4.42, 10.4.43, 10.4.44 for more information. >>> >>> The above paragraph seems a bit confusing, there is no reference >>> to caching mode for for VCMD... some suggestion below. >>> >>> Enabling IOMMU in a guest requires communication with the host >>> driver for certain aspects. Use of PASID ID to enable Shared Virtual >>> Addressing (SVA) requires managing PASID's in the host. VT-d 3.0 >>> spec provides a Virtual Command Register (VCMD) to facilitate this. >>> Writes to this register in the guest are trapped by Qemu and >>> proxies the call to the host driver.... >> >> Yours is better. Will use it. >> > I will roll that in to v7 >>> >>> >>>> >>>> This patch adds the enlightened PASID allocation/free interfaces >>>> via the virtual command register. >>>> >>>> Cc: Ashok Raj <ashok.raj@intel.com> >>>> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com> >>>> Cc: Kevin Tian <kevin.tian@intel.com> >>>> Signed-off-by: Liu Yi L <yi.l.liu@intel.com> >>>> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >>>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> >>>> Reviewed-by: Eric Auger <eric.auger@redhat.com> >>>> --- >>>> drivers/iommu/intel-pasid.c | 83 >>>> +++++++++++++++++++++++++++++++++++++++++++++ >>>> drivers/iommu/intel-pasid.h | 13 ++++++- >>>> include/linux/intel-iommu.h | 2 ++ 3 files changed, 97 >>>> insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/iommu/intel-pasid.c >>>> b/drivers/iommu/intel-pasid.c index 040a445be300..76bcbb21e112 >>>> 100644 --- a/drivers/iommu/intel-pasid.c >>>> +++ b/drivers/iommu/intel-pasid.c >>>> @@ -63,6 +63,89 @@ void *intel_pasid_lookup_id(int pasid) >>>> return p; >>>> } >>>> >>>> +static int check_vcmd_pasid(struct intel_iommu *iommu) >>>> +{ >>>> + u64 cap; >>>> + >>>> + if (!ecap_vcs(iommu->ecap)) { >>>> + pr_warn("IOMMU: %s: Hardware doesn't support >>>> virtual command\n", >>>> + iommu->name); >>>> + return -ENODEV; >>>> + } >>>> + >>>> + cap = dmar_readq(iommu->reg + DMAR_VCCAP_REG); >>>> + if (!(cap & DMA_VCS_PAS)) { >>>> + pr_warn("IOMMU: %s: Emulation software doesn't >>>> support PASID allocation\n", >>>> + iommu->name); >>>> + return -ENODEV; >>>> + } >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +int vcmd_alloc_pasid(struct intel_iommu *iommu, unsigned int >>>> *pasid) +{ >>>> + u64 res; >>>> + u8 status_code; >>>> + unsigned long flags; >>>> + int ret = 0; >>>> + >>>> + ret = check_vcmd_pasid(iommu); >>> >>> Do you have to check this everytime? every dmar_readq is going to >>> trap to the other side ... >> >> Yes. We don't need to check it every time. Check once and save the >> result during boot is enough. >> >> How about below incremental change? >> > Below is good but I was thinking to include vccap in struct > intel_iommu{} where cap and ecaps reside. i.e. > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h > index 14b87ae2916a..e2cf25c9c956 100644 > --- a/include/linux/intel-iommu.h > +++ b/include/linux/intel-iommu.h > @@ -528,6 +528,7 @@ struct intel_iommu { > u64 reg_size; /* size of hw register set */ > u64 cap; > u64 ecap; > + u64 vccap; > > Also, we can use a static branch here.
Yeah! Good idea.
Best regards, baolu
| |