Re: [PATCH v8 06/10] iommu/vt-d: Cache virtual command capability register

Jacob Pan
2020-01-09T21:54:02Z

On Wed, 18 Dec 2019 11:25:27 +0800
Lu Baolu <baolu.lu@linux.intel.com> wrote:

> Hi,
>
> On 12/17/19 3:24 AM, Jacob Pan wrote:
> > Virtual command registers are used in the guest only, to prevent
> > vmexit cost, we cache the capability and store it during
> > initialization.
> >
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > ---
> > drivers/iommu/dmar.c | 1 +
> > include/linux/intel-iommu.h | 4 ++++
> > 2 files changed, 5 insertions(+)
> >
> > diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
> > index f2f5d75da94a..3f98dd9ad004 100644
> > --- a/drivers/iommu/dmar.c
> > +++ b/drivers/iommu/dmar.c
> > @@ -953,6 +953,7 @@ static int map_iommu(struct intel_iommu *iommu,
> > u64 phys_addr) warn_invalid_dmar(phys_addr, " returns all ones");
> > goto unmap;
> > }
> > + iommu->vccap = dmar_readq(iommu->reg + DMAR_VCCAP_REG);
> >
> > /* the registers might be more than one page */
> > map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap),
> > diff --git a/include/linux/intel-iommu.h
> > b/include/linux/intel-iommu.h index ee26989df008..4d25141ec3df
> > 100644 --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -189,6 +189,9 @@
> > #define ecap_max_handle_mask(e) ((e >> 20) & 0xf)
> > #define ecap_sc_support(e) ((e >> 7) & 0x1) /* Snooping
> > Control */
> > +/* Virtual command interface capabilities */
> > +#define vccap_pasid(v) ((v & DMA_VCS_PAS)) /* PASID
> > allocation */
>
> Has DMA_VCS_PAS ever been defined?
>
Good catch, it is in the next patch, need to move the #define here.
Thanks!

> Best regards,
> baolu
>
> [...]

[Jacob Pan]