Re: [Xen-devel] [PATCH v2 12/13] [RFC] iommu: VT-d: Squash map_pages/unmap_pages with map_page/unmap_page

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

this patch alone looks OK to me. but I haven't found time to review
the whole series to judge whether below change is necessary.

> From: Oleksandr Tyshchenko [mailto:olekstysh@xxxxxxxxx]
> Sent: Tuesday, September 12, 2017 10:44 PM
> 
> Hi.
> 
> Gentle reminder.
> 
> On Mon, Aug 21, 2017 at 7:44 PM, Oleksandr Tyshchenko
> <olekstysh@xxxxxxxxx> wrote:
> > Hi, all.
> >
> > Any comments?
> >
> > On Tue, Jul 25, 2017 at 8:26 PM, Oleksandr Tyshchenko
> > <olekstysh@xxxxxxxxx> wrote:
> >> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >>
> >> Reduce the scope of the TODO by squashing single-page stuff with
> >> multi-page one. Next target is to use large pages whenever possible
> >> in the case that hardware supports them.
> >>
> >> Signed-off-by: Oleksandr Tyshchenko
> <oleksandr_tyshchenko@xxxxxxxx>
> >> CC: Jan Beulich <jbeulich@xxxxxxxx>
> >> CC: Kevin Tian <kevin.tian@xxxxxxxxx>
> >>
> >> ---
> >>    Changes in v1:
> >>       -
> >>
> >>    Changes in v2:
> >>       -
> >> ---
> >>  xen/drivers/passthrough/vtd/iommu.c | 138 +++++++++++++++++--------
> -----------
> >>  1 file changed, 67 insertions(+), 71 deletions(-)
> >>
> >> diff --git a/xen/drivers/passthrough/vtd/iommu.c
> b/xen/drivers/passthrough/vtd/iommu.c
> >> index 45d1f36..d20b2f9 100644
> >> --- a/xen/drivers/passthrough/vtd/iommu.c
> >> +++ b/xen/drivers/passthrough/vtd/iommu.c
> >> @@ -1750,15 +1750,24 @@ static void
> iommu_domain_teardown(struct domain *d)
> >>      spin_unlock(&hd->arch.mapping_lock);
> >>  }
> >>
> >> -static int __must_check intel_iommu_map_page(struct domain *d,
> >> -                                             unsigned long gfn,
> >> -                                             unsigned long mfn,
> >> -                                             unsigned int flags)
> >> +static int __must_check intel_iommu_unmap_pages(struct domain *d,
> >> +                                                unsigned long gfn,
> >> +                                                unsigned int order);
> >> +
> >> +/*
> >> + * TODO: Optimize by using large pages whenever possible in the case
> >> + * that hardware supports them.
> >> + */
> >> +static int __must_check intel_iommu_map_pages(struct domain *d,
> >> +                                              unsigned long gfn,
> >> +                                              unsigned long mfn,
> >> +                                              unsigned int order,
> >> +                                              unsigned int flags)
> >>  {
> >>      struct domain_iommu *hd = dom_iommu(d);
> >> -    struct dma_pte *page = NULL, *pte = NULL, old, new = { 0 };
> >> -    u64 pg_maddr;
> >>      int rc = 0;
> >> +    unsigned long orig_gfn = gfn;
> >> +    unsigned long i;
> >>
> >>      /* Do nothing if VT-d shares EPT page table */
> >>      if ( iommu_use_hap_pt(d) )
> >> @@ -1768,78 +1777,60 @@ static int __must_check
> intel_iommu_map_page(struct domain *d,
> >>      if ( iommu_passthrough && is_hardware_domain(d) )
> >>          return 0;
> >>
> >> -    spin_lock(&hd->arch.mapping_lock);
> >> -
> >> -    pg_maddr = addr_to_dma_page_maddr(d, (paddr_t)gfn <<
> PAGE_SHIFT_4K, 1);
> >> -    if ( pg_maddr == 0 )
> >> +    for ( i = 0; i < (1UL << order); i++, gfn++, mfn++ )
> >>      {
> >> -        spin_unlock(&hd->arch.mapping_lock);
> >> -        return -ENOMEM;
> >> -    }
> >> -    page = (struct dma_pte *)map_vtd_domain_page(pg_maddr);
> >> -    pte = page + (gfn & LEVEL_MASK);
> >> -    old = *pte;
> >> -    dma_set_pte_addr(new, (paddr_t)mfn << PAGE_SHIFT_4K);
> >> -    dma_set_pte_prot(new,
> >> -                     ((flags & IOMMUF_readable) ? DMA_PTE_READ  : 0) |
> >> -                     ((flags & IOMMUF_writable) ? DMA_PTE_WRITE : 0));
> >> +        struct dma_pte *page = NULL, *pte = NULL, old, new = { 0 };
> >> +        u64 pg_maddr;
> >>
> >> -    /* Set the SNP on leaf page table if Snoop Control available */
> >> -    if ( iommu_snoop )
> >> -        dma_set_pte_snp(new);
> >> +        spin_lock(&hd->arch.mapping_lock);
> >>
> >> -    if ( old.val == new.val )
> >> -    {
> >> +        pg_maddr = addr_to_dma_page_maddr(d, (paddr_t)gfn <<
> PAGE_SHIFT_4K, 1);
> >> +        if ( pg_maddr == 0 )
> >> +        {
> >> +            spin_unlock(&hd->arch.mapping_lock);
> >> +            rc = -ENOMEM;
> >> +            goto err;
> >> +        }
> >> +        page = (struct dma_pte *)map_vtd_domain_page(pg_maddr);
> >> +        pte = page + (gfn & LEVEL_MASK);
> >> +        old = *pte;
> >> +        dma_set_pte_addr(new, (paddr_t)mfn << PAGE_SHIFT_4K);
> >> +        dma_set_pte_prot(new,
> >> +                         ((flags & IOMMUF_readable) ? DMA_PTE_READ  : 0) |
> >> +                         ((flags & IOMMUF_writable) ? DMA_PTE_WRITE : 0));
> >> +
> >> +        /* Set the SNP on leaf page table if Snoop Control available */
> >> +        if ( iommu_snoop )
> >> +            dma_set_pte_snp(new);
> >> +
> >> +        if ( old.val == new.val )
> >> +        {
> >> +            spin_unlock(&hd->arch.mapping_lock);
> >> +            unmap_vtd_domain_page(page);
> >> +            continue;
> >> +        }
> >> +        *pte = new;
> >> +
> >> +        iommu_flush_cache_entry(pte, sizeof(struct dma_pte));
> >>          spin_unlock(&hd->arch.mapping_lock);
> >>          unmap_vtd_domain_page(page);
> >> -        return 0;
> >> -    }
> >> -    *pte = new;
> >> -
> >> -    iommu_flush_cache_entry(pte, sizeof(struct dma_pte));
> >> -    spin_unlock(&hd->arch.mapping_lock);
> >> -    unmap_vtd_domain_page(page);
> >>
> >> -    if ( !this_cpu(iommu_dont_flush_iotlb) )
> >> -        rc = iommu_flush_iotlb(d, gfn, dma_pte_present(old), 1);
> >> -
> >> -    return rc;
> >> -}
> >> -
> >> -static int __must_check intel_iommu_unmap_page(struct domain *d,
> >> -                                               unsigned long gfn)
> >> -{
> >> -    /* Do nothing if hardware domain and iommu supports pass thru. */
> >> -    if ( iommu_passthrough && is_hardware_domain(d) )
> >> -        return 0;
> >> -
> >> -    return dma_pte_clear_one(d, (paddr_t)gfn << PAGE_SHIFT_4K);
> >> -}
> >> -
> >> -/* TODO: Optimize by squashing map_pages/unmap_pages with
> map_page/unmap_page */
> >> -static int __must_check intel_iommu_map_pages(struct domain *d,
> >> -                                              unsigned long gfn,
> >> -                                              unsigned long mfn,
> >> -                                              unsigned int order,
> >> -                                              unsigned int flags)
> >> -{
> >> -    unsigned long i;
> >> -    int rc = 0;
> >> -
> >> -    for ( i = 0; i < (1UL << order); i++ )
> >> -    {
> >> -        rc = intel_iommu_map_page(d, gfn + i, mfn + i, flags);
> >> -        if ( unlikely(rc) )
> >> +        if ( !this_cpu(iommu_dont_flush_iotlb) )
> >>          {
> >> -            while ( i-- )
> >> -                /* If statement to satisfy __must_check. */
> >> -                if ( intel_iommu_unmap_page(d, gfn + i) )
> >> -                    continue;
> >> -
> >> -            break;
> >> +            rc = iommu_flush_iotlb(d, gfn, dma_pte_present(old), 1);
> >> +            if ( rc )
> >> +                goto err;
> >>          }
> >>      }
> >>
> >> +    return 0;
> >> +
> >> +err:
> >> +    while ( i-- )
> >> +        /* If statement to satisfy __must_check. */
> >> +        if ( intel_iommu_unmap_pages(d, orig_gfn + i, 0) )
> >> +            continue;
> >> +
> >>      return rc;
> >>  }
> >>
> >> @@ -1847,12 +1838,17 @@ static int __must_check
> intel_iommu_unmap_pages(struct domain *d,
> >>                                                  unsigned long gfn,
> >>                                                  unsigned int order)
> >>  {
> >> -    unsigned long i;
> >>      int rc = 0;
> >> +    unsigned long i;
> >> +
> >> +    /* Do nothing if hardware domain and iommu supports pass thru. */
> >> +    if ( iommu_passthrough && is_hardware_domain(d) )
> >> +        return 0;
> >>
> >> -    for ( i = 0; i < (1UL << order); i++ )
> >> +    for ( i = 0; i < (1UL << order); i++, gfn++ )
> >>      {
> >> -        int ret = intel_iommu_unmap_page(d, gfn + i);
> >> +        int ret = dma_pte_clear_one(d, (paddr_t)gfn << PAGE_SHIFT_4K);
> >> +
> >>          if ( !rc )
> >>              rc = ret;
> >>      }
> >> --
> >> 2.7.4
> >>
> >
> >
> >
> > --
> > Regards,
> >
> > Oleksandr Tyshchenko
> 
> 
> 
> --
> Regards,
> 
> Oleksandr Tyshchenko
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